johnsmachines

machines which I have made, am making, or intend to make, and some other stuff. If you find this site interesting, please leave a comment. I read every comment and respond to most. n.b. There is a list of my first 800 posts in my post of 17 June 2021, titled "800 Posts"

Armstrong Breech Block Rest

In the above photograph, taken I think of a 110pr Armstrong breech loader in Canada, of a Garrison mounted gun, there are several very interesting features. The Smith’s elevating screw for instance, and the remnants of the left hand breech tangent sight. But I am particularly looking at the flat surfaced item which is attached to the top of the breech. It took me some time to work out the function of the rather complex shaped item.

The breech block, which weighed 130lbs, had to be lifted out of the breech by two strong gunners to permit swabbing of the bore from the breech aperture (also visible in the photo), then loading of the next projectile and gunpowder bag, after which the breech block was lifted back into position and screwed tightly closed prior to the next firing.

Ah….. the flat topped attachment is where the breech block was placed while the swabbing and loading took place!

So I set about making the breech block rest (as I called it) for my model.

The rest looked complex and difficult to model. The inner surface had to fit the external surface of the breech, including two convex fillets. The external surface has to fit the breech block, without denting or otherwise damaging it despite its considerable weight and frequent manhandling. And there are holes for 6 attaching screws.

First I turned a disk in LG2 bronze. The interior surface fitted closely over the breech, including the convex fillets. I used a bullnose milling cutter to turn the fillets.
Then the top surface using the scarey shell cutter. I handle this cutter with great care because it is razor sharp.
Then CNC milled the shapes which hold the breech block securely…
And finally drilled the screw holes and parted the fitting from the bronze disk. The under side.
and the top side.
Here the breech block rest is Loctited in position, ready for the screw holes to be drilled into the breech and the screws fitted.
The breech block resting in place, ready for reloading.

Now, dear readers, I must inform you that I have only enough WordPress memory for another one or two posts and a few photographs.

The Armstrong 110pr breech loader cannon model project is almost finished.

The remaining parts, including the Smith’s elevating screw, carriage wheels, rope eye bolts and capstain were all described in the build of the Armstrong 80pr rifled muzzle loading model cannon, so I will not repeat those details for the 110 pr.

I will leave the remaining small memory for the assembled model of the 110 breech loader, in a few weeks time.

And since I will not delete any more old posts, that will be my final post. (unless WordPress changes their policy of not increasing memory limits. And I do not expect that to happen.)

In the final post I will notify you, my readers, of the site where I will post photos of future projects. Not quite yet decided, but it will NOT be WordPress.

2->3 Phase Power. Laser Engraving.

My workshop uses a 6kw Phase Changer machine to convert the 2 phase supply to 3 phases, which is required by my CNC mill, DRO mill and big lathe.

When I turned it on 2 days ago, I was startled by a very loud “bang” and a puff of black smoke from the phase changer. And no power output, unsurprisingly. On opening up the machine I was pleased to note that the (very expensive) transformer looked intact. But one of the large capacitors looked a bit ragged.

I restarted the unit with my iPhone recording so I could show the manufacturer. The culprit is the second capacitor from the top. The replacement capacitor came yesterday.

So I have been limited to single phase equipment for the past 2 days. It did force me to finish some outstanding tasks….

….Like making the traversing platform axle washers…
….and making the tow bar….and finish installing the wheels.

and yesterday my colleague and friend Stuart T used his 30w fibre laser to engrave the manufacturer name, number, barrel weight, date, and Queen Victoria’s cypher.

Stuart and his laser. He reckons that it has been used more for my model cannons than his own work! The orange machine is a tiny CNC mill which Stuart made a few years ago.
The laser in action
The engraving as it first appears. Some polishing is required to remove the rectangle around the cypher and to sharpen the image outlines. The trunnion ring is still waiting for a cleanup after being heat shrink fitted.

Traversing Platform Wheels

30mm diameter, 11mm thick, a rail groove on the edge, circular divots on the faces. Simple!

But…

I decided to make them from stainless steel. And tonight I have multiple small cuts on my fingers to prove it.

Stainless steel is a bugger to machine. It requires slow feeds, deepish cuts, COOLANT, and sharp tools. Carbide is OK for roughing, but for accurate final surfaces, sharp high speed steel is required. And it produces razor wire. Copious amounts of it.

End result. Not perfect, but as good as I can manage. It took me 2 days to make 8 of these wheels. More work is required on the axles.

First I machined some 40mm stainless rod down to 31mm. Too late I realised that was too big.

Then I used a HSS form tool bit to cut the edge groove. But got too much chatter. So spent some time getting the coolant pump and nozzle working. Some improvement, but still some chatter. So I switched to a HSS parting tool 3mm wide, and that seemed to work well. The DRO was handy to achieve the final groove depth of 2.5mm, and 6mm wide. And then to take 0.5mm off each face to produce a boss 12.7mm wide and 0.5mm deep.

Then completed the parting off. Oh. Forgot to mention the 5mm shaft hole which was drilled.

But when I tried to install the wheels in the wheel brackets I realised that I need to remove about 0.1mm from each boss. This is the setup which I used.

A diamond cup wheel in the chuck, and the wheel wheel siting on parallels and held in the drill press vice. This worked pretty well, except that the quill adjustments on the drill press were a bit coarse. It would have been better in the mill with a DRO.
Oh. And I forgot. I used a HSS ball nose milling bit in the CNC mill, with a spray lubricant coolant, to make the face grooves. By this stage I was absolutely convinced of the need for the lubricant coolant. It made a huge difference to the surface finish. The vice did leave little dents in the surfaces of the wheels, but I had left a final machining allowance of 0.5mm to be tidied up in the lathe.

So, the first pic is the current situation, . Next steps are to make the washers for the axles, trim the axles to length, and drill/install retaining pins. These steps always seem to require at least double the predicted workshop time.

Option 1. Ironwood.

The problem was that the 4 wheel brackets needed the wheel recess deepened by 2.5mm, and the brass shape had few clampable surfaces.

So, I tried option 1.

I machined a wooden jig to hold the bracket in the milling machine vice. The wood is Australian desert ironwood, which is unbelievably hard, but would not mark the brass. The pocket was machined to the diameter of the circular base of the bracket, and then sawn in half.

The bracket was clamped in the jig and squeezed tightly in the vice. Then machined with the slot cutter, the required 2.5mm deeper. The workpiece showed NO tendency to move.

Mission Accomplished!

Cannon Wheel Brackets. Cast or Machine?

Original brackets on the Elsternwick 80pr Armstrong RML’s. They appear to be castings.
Another wheel bracket style. This one on the Armstrong 80pr at Port Fairy. Cast from a different mold.

Previously I have made model wheel brackets using 2 different methods…. 1. casting 2.turning/milling

This bracket was cast from aluminium. It looks different from the Elsternwick example above, but is close to the original Port Fairy original.
This one was turned from brass, and was installed on the model copied from the Elsternwick originals. Not too dissimilar from the original, but still not quite right.

So, these are the wheel brackets which I have made for the current model Armstrong 110pr…

These are hot off the milling machine, and not yet finished. Those sharp edges will all be rounded and milling marks polished out.

I think that when these are finished they will look closer to the original than either of the previous examples, and they certainly look more robust and fit for purpose IMO. So, what do you think?

The above wheel brackets were milled from 38mm brass rod….

12.7mm 3 flute HSS endmill, 8mm deep cuts, CNC mill.
The slot was cut with a 5mm width slotter. 3 passes to get 11mm width. First pass shown here.
75mm diameter, 5mm thick slotter. Shop made spindle fits into ER40 chuck. First ever use of this slotter which I bought years ago.

On reviewing this post I noticed that the slot for the wheel looked a bit shallow, and when I measured it I found that it is 2.5mm too shallow. A simple mistake, but must be fixed.

The problem is how to hold the workpiece while cutting the slot the extra 2.5mm deeper.

Possibilities. 1. make a circular jig to clamp the bracket in the milling vice. 2. just hold the bracket in the milling vice and hope for the best. 3.solder a 38mm cylinder to the top of the bracket, and hold the extension in the vice. 4. make new brackets.

At this moment I am thinking that I will try 1. and if unsuccessful move to 4.

Watch this space…..

Making a Woodworking File.

The Armstrong 110pr model cannon trunnions sit in semicircular cutouts in the carriage cheeks. In the model the cutouts are 20mm diameter, and they are slightly deeper than semicircular. Making the “slightly bigger than semicircular” cutouts is complicated by the fact that the cheeks toe in towards the front, by 2.65º.

When I originally cut out the cheeks I made the cutouts 18mm diameter, allowing 2mm to be removed at the assembly time, and to then remove some extra material to cope with the toe-in angle. I did not know in advance how that would be done, but I figured that I would use a drill or reamer at the correct angle to remove the extra material.

Today was the day.

But when I was actually confronted with the task, I realised how difficult the job was actually going to be. I also realised that a drill or reamer was NOT going to do the job accurately or neatly enough.

These are the assembled carriages with the undersize trunnion cutouts, which do not take into account the toe-in angles. (
Since this photo was taken, the bolts have all been finished to length. See later photo.)

Then I had a brainwave. And I am really proud of this one. I made a round file, exactly 20mm diameter, and long enough do file the cut-outs together, exactly in line.

How to make a file?

And how to make the teeth small enough so they leave a smooth finish with no edge tear-outs?

A 20mm diameter piece of silver steel, long enough to allow filing movements plus handles. Here I am applying a fine knurl with the shop made tool which I made a decade or more ago. It is a clamp type, and can apply a lot of pressure. Run at 200rpm, well oiled.
I chose the finest pattern knurling wheels.

Ah! But I forgot something. When I measured the diameter of the “file” the 20mm shaft now measured 20.25mm. I had forgotten that knurling INCREASES the effective diameter. So I turned off the knurls and machined the shaft down to 19.75mm, and repeated the knurling. The diameter was now 20.05mm which I considered acceptable.

Since I was only intending to file wood, I did not bother hardening the silver steel.

The “file” after a few minutes enlarging the cut-outs.
After one minute of gently rotating the file, I could see that it was working!
One finished – in 3 minutes, and one to go (the top one)
And the trunnions fit the cut-outs perfectly!

Garrison based cannons did not use trunnion caps, unlike the naval versions, relying on the weight of the barrel to keep it in place. The centre of the trunnion is just below the top surface of the carriage cheek.

The file worked well in hardwood. I would have hardened the steel if it was to be used on brass or other metal.

Making Slotted Nuts with a Grinding Disk

The carriage cheeks for the Armstrong 110pr cannon have 10 roughly vertical bolts which attach the wooden slides, and also bolt together the thick planks which make up the cheeks.

Some woodworking on the vertical mill, using a very sharp and scarey shell cutter. I used to do a lot of woodworking, but these days I use the metalworking tools at their highest speeds to do accurate cuts in wooden parts. Here milling the rebates which fit the carriage into the traversing platform of the Armstrong 110pr.

The nuts for the bolts are all at the bottom end, and are buried in the slides. In previous model cannons I have milled pockets for the nuts, and tightened the nuts with a socket spanner, but I was not happy with the large diameter of the pocket which was needed to accomodate the socket spanner.

So, this time I decided to tighten the nuts using a screw driver, having cut a slot in the surface of the nuts.

This is an M4 nut, with a slot cut into the surface, which will be tightened with a special screwdriver. How to cut such a tiny slot? (excuse my dirty finger. This photo was taken after several hours in the workshop.)
The screwdriver tip which has been modified with a Dremel, to drive the slotted nuts.
This is the setup for cutting the slot. the nut is screwed onto some sacrificial threaded 4mm rod. The slot is cut with a thin cutting disk, 1mm thick, mounted onto a shop made mandrel which fits into an ER40 collet on the vertical mill. A bit of fiddling with the height settings, but once it was set, making the slotted nuts was very quick and easy. The slot was 2mm deep in the 4mm deep nuts. Plenty of thread remaining to tighten the nuts.
Slotted nuts on the right. Ordinary unslotted nuts on the left, which cannot be tightened except by making bigger holes, or slotting the nuts, which is what I did.

Armstrong 110pr Carriage-1

With the barrel almost finished (except for sights and engraving), I have returned to woodworking. The carriage was made of wood in the 1860’s.

I had previously cut out the carriage sides and the slide blocks, but now the parts need to be bolted together. Today I marked out the bolt holes, and drilled some. The holes were 4mm diameter, and up to 90mm long. Definitely “deep drilling”, despite being in wood. Due to the figuring in the wood it can sometimes be difficult to keep long series drill bits from wandering off to the sides.

The sides were pinned togetherand drilled in pairs after marking. The bolts are used to hold the slides onto the sides, and all are at different angles. Due to the tendency of the long series drill bits to wander, I started at the top where the bolts are visible, and finished at the bottom, where eventually they will not be visible.
The marks were lined up under a centre bit, and using a square to get the hole as true as possible.
2 holes needed to have pockets cut with an end mill first. Yes, I know. Should not have used a 3 jaw drill chuck to hold the end mill, but it worked on this steeply sloped part.
After the drilling was finished, I could not wait to set up the barrel on the carriage to see how it would appear.

Next job is to continue the bolt holes through the slide blocks. And to make the transom. And then to enlarge the trunnion cutout to the correct size and angle.

The trunnion holes in the cheeks require some enlargement. The clearance of the trunnion shoulders to the carriage sides is a very neat fit.

Breech Block Handles

I am glad that I had no visitors to my workshop in the past 2 days.

The language in the workshop has been a touch foul.

Because I have been making handles for the previously made bronze breech blocks.

The handles are very small, very exacting, and difficult. In a word, I struggled.

End result photo….

Those little handles were used to lift out the 130lb breech block by 2 gunners. The handles swivel, and push down on the barrel, to lever the block out of the gas tight seal the block makes with the end of the bore of the barrel. As you can see from the scale of of my finger tips, they ARE very small.

I was not enthusiastic about this job. I had a feeling that it would be a bugger. And so it was.

First task to cut out the top of the handle bracket. Piece of cake with CNC.
Next, drill a hole into the bronze block and silver solder it into permanent position. Also, straightforward. The top was Loctited into position with Loctite 620, so the silver solder was not disturbed. So far so good.
Next job, make the actual handles. I milled a round rod with appropriately sized flats, then annealed some brass rod, and wound it around the shaped steel. Total failure. Did not take the shape accurately, and sprung outwards. So I tried it in copper. That worked better…
The copper wire was out of the scrap bin. 2.4mm diameter.
Then milled some brass rectangular section (6x4mm) and silver soldered the copper pieces to it.
Then cut the brass approximately to length.
Slit the brass to 2mm width on the mill.
Drilled the fastener holes and attached to the breech block with BA10 bolts and nuts.
And ended up with a breech block which can be levered out, and replaced into position reasonably accurately and consistently.

All straightforward.

So why all of the bad language?

Well, I needed 2 of these, so 4 handles. I made 2 spare.

I dropped one. Could not find it, despite hours of searching, including using a fibre optic 5mm diameter device to look under the milling machine and sweeping the floor. (no snakes in this cold weather. I hope). But no luck, so I made another.

Another handle jammed in the Dremel drill. I hear it hit the tin wall 7 meters away. I did look for a minute or 2, then succumbed to common sense and made another. The language really was foul.

Anyway. You have seen the final result. not too bad. Another bit of brass bling.

Breech Screw Weighted Handle

Yesterday I went with the children and grandchildren to the stage show musical “Cinderella”, by Rogers and Hammerstein, so I had to cut my workshop session short.

But in the few hours available I attached the weights to the weighted handle, and the lugs which contact the screw handle.

The weights were silver soldered to the handle, and the lugs were Loctited into position. I chose Loctite 620 rather than silver solder for the lugs, because I used different setups for the weights and lugs, and did not want to risk disrupting the silver solder from the weights joins when I attached the lugs. Some finishing required to remove the heat scale and lug protrusions. Even at model scale, the weighted handle works really well.

Oh. And by the way….Cinderella was marvellous! Enjoyed by everyone from age 6 to 72.

Appreciative audience after the show, exiting The Regent Theatre, Melbourne.

A Lot of Swarf

The billet of 1020 steel which I used to make the Armstrong 110pr breech loader cannon barrels weighed a bit over 10kg for each barrel.

305mm long, 76mm diameter, 10+kg

That leaves over 6kg of swarf for each barrel! How did I do it? rI just removed all of the steel which was not cannon barrel (apologies to Michaelangelo).

Heat Shrink Installation of TRUNNION RING

The original trunnion rings of the Armstrong 110pr breech load cannons were made with a smaller internal diameter than the barrel. Then the ring was heated, installed, and it shrunk firmly into its permanent position. Heat shrinking multiple coil cylinders to build up the cannon was shown to be a very strong method, albeit expensive.

I decided to try the same method with my 1:10 model, and discussed the method at the recent GSMEE meeting. I listened carefully to the advice from members, read Machinery’s Handbook on the subject, and was ready to proceed.

The ring internal diameter was turned to 0.05-0.06 mm smaller than the diameter of the barrel where it would be positioned.

This is the pottery oven which I used to heat up the ring to 550ºc/1022ºf. All necessary tools, gloves, etc ready.

I was also told that once the ring contacts the barrel, the working time before the ring contracts is very short. So I was advised to make a jig so the ring drops exactly into the correct position. I made the jig from hardwood, and had a fire extinguisher handy.(but the extinguisher was not actually required.)
CNC routing to make the jig. The trunnions fitted with 0.25mm clearance.

I let the ring soak up the heat for an hour or more.

Lifted it out with pliers, carefully lowered it down the barrel (having earlier has a couple of practice runs), and felt it slide easily into position.

Another ring followed later and it also dropped easily into position. I had to rotate it, and noted that it locked up after only 10-15 seconds, so the working time is indeed very brief!

The first ring in position. The second one was installed a few moments later, after the jig was removed. The barrel soaked up the heat, and was too hot to handle for over an hour. Note the scorch marks on the wood jig. And the line up scratches.
I had mucked up the internal ring diameter of the second barrel, so used Loctite 620 after cleaning the surfaces with acetone and then the Loctite 7071 prep spray. Unexpectedly, probably because I did not use the jig with the Loctite join, I had more trouble lining up the marks with this one. I am sure that both will be strong enough for these models. After that I turned the 1º taper on the distal end of the barrels (the “chase”). The flat section is for the bracket which the breech block is placed on for loading the projectile and charge. The flat was also the reference plane for the trunnions.

I will clean up the blackened heat affected trunnion ring later. This was a very satisfying day in the workshop.

Trunnion Rings Completed.

Today I turned the trunnions.

The centres were measured, marked and drilled. The squared end was held in a 4 jaw chuck and the end to be turned was held in the tailstock. Turned to 20mm dia with a “Diamond” tool holder and HSS 1/4″ cutter from Eccentric Engineering.
Then the turned end was held in an ER40 collet chuck to avoid marring the surface, and the tailstock end was turned.
One finished, one end to go.
Then I used the undersized laser cut parts to turn another “coil” (solid steel in the model, not a wound coil as in the full size cannon), also to be heat shrunk to the barrel.

Next step will be to turn the barrel diameter down to about 0.06-0.07mm bigger than the internal diameters of these parts. I will try to take some photos of the heat shrinking process for the next post.

Making the Trunnion Ring for the Armstrong 110pr

Unfortunately the laser cut trunnion ring blanks were unusable because they were undersize. Rather than wait for another run of laser cut parts, with 3-5% increase in size to cope with the problem, I decided to mill the shapes from some old 27.5mm thick mild steel. In my last post I showed the preparation of the stock.

I made 2 of the ring blanks today. They have a 45mm hole, and to speed up the milling process I chose to use my magnet drill and a 35mm annular cutter to get the hole started…

It took about a minute to make a 35mm diameter hole in 27mm steel. Easy as. I had previously centre drilled the hole positions on the mill. I bought this magnet drill 18 years ago when I was building a large farm shed.
Before drilling the holes I had zeroed in the steel plate on the milling machine, and used the red locating device to replace the steel in the same position.
The left hole milled to 45mm diameter, 4mm depth per cut with a newish 8mm carbide bit. Just starting the second one. Much easier enlarging an existing hole than milling a deep slot.
Milling the outline, ramping down…..2500rpm, 150mm/min
…and I quickly added a spray-mister to provide lubrication, cooling and chip clearing from the deepening slot.
I did run into a problem with the tabs. I made them 1mm thick, but forgot that Vectric calculates the tab thickness from the bottom of the cut, not the bottom of the material. And the tabs broke before the milling had finished. Fortunately the workpieces survived.
The parts had 5mm taken off the wings which will later become the trunnions, then used a rounding over milling cutter as a form tool in the lathe to make a rounded fillet.
2 of these made today. Tomorrow I will turn the trunnions from the squarish ends.

Model Armstrong 110pr Breech Screw Handle

As explained in the previous post, it was crucial that the breech screw was tightened securely.

Watch the following YouTube video of a demonstration firing of a 110pr at Fort Nelson, video’d by Nick Cafferata, and used here with his permission. Note how the weighted handle was swung by 2 gunners and repeatedly knocked to ensure secure closure. Also note the volume of smoke from the firing, and this was a charge of only 2lb, compared with the 10-11 lb used in 1861.

The laser cut parts for the screw handle (left) were excellent. Unfortunately the blank for the trunnion ring was slightly too small so I will use another method to cut another using my CNC mill.
Milling the screw octagon on the breech screw. CNC rotary table. Beautifully accurate.
Octagonal piece heat shrunk to breech screw. I probably could have cold pressed it on, but I wanted to try heat shrinking because that method will be required later when fitting the trunnion ring. It is strongly held together, not budging when I turned the rear surface to 4mm thickness.
1.6mm drill for the pins. This worked well after I loctited the handle to the screw before drilling. 25mm depth of drilling definitely qualifies as deep drilling. Then I heated the assembly to break the Loctite bond. Then turned a 1.6mm wide, 0.8mm deep groove in the shaft using the drilling marks as a positioning guide.


Facing the handle and screw. This was also completed before breaking the Loctite bond. Not a precision task, so quite happy to use the 3 jaw chuck, which is actually surprisingly accurate.

The central 18mm diameter shaft was also heated to break its Loctite bond and the shaft came free.

Next job is to make and attach the blocks to the handle which knock the octagon/breech screw, and the heavy weights to the ends of the handle which enhance the momentum of the action.

I had this piece of mild steel 28mmx168mmx600mm left over from a farm machinery job years ago (a deep ripper for a bull dozer, for preparing the ground prior to planting olive trees.)
It was rusted from sitting in a pile of steel for 10-15 years, so I took off 0.5mm from each face to flatten it and clean it up.

Watch this space to see it being CNC’d into a trunnion ring…….

Armstrong RBL 110pr Model Breech Block Seat.

If the screw which held the breech block in place was not tightened, when the gun was fired, explosive corrosive gases would escape backwards rather than propelling the projectile. An inefficient and destructive result.

If the screw was not not tightened at all, the breech block, which weighed 130lb, could be ejected with great force, and devastating, potentially fatal results to the gun crew.

So it was important that a gas tight seal was achieved when the block was inserted and tightened. That required a seat like a valve seat in an internal combustion engine, and a corresponding 45º angle on the breech block.

First I made the breech block. The plug was turned from LG2 bronze. This will seat against the steel barrel bore. In the original the block was made of steel or iron, and it seated against a copper insert seat. I decided that it would be too fiddly and difficult to reproduce the original steel/copper system, so I substituted the bronze block which fitted against the steel end of bore in a 45º seat.

cnc turning the bronze breech plug. The cylindrical section fits into the 18mm bore. A similar cylindrical section on the other end fits into the breech screw. The 45º section is seen.
A further final contour, then parting the plug from the bronze bar. I finished the parting by using a hacksaw.
The plug is 31mm diameter, 16mm thick.

I used 2 tools to make the seat. A commercial carbide seat cutter, and a shaped stone to finish.

The brass shaft and pilot were each 18mm diameter, and fitted neatly in the bore and breech screw.
The stone was given a 45º bevel using a diamond. The ways were covered and thoroughly cleaned afterwards.

The seat was cut with the carbide cutter, by hand and using cutting fluid. When it was 1-2mm wide, some chatter marks were just visible, so they were polished out using the stone, also by hand.

The chatter is visible, along with the chips which were produced by the carbide cutter. I don’t have a good photo of the end result, but it looked much better than this.
The hole underneath was to drain water after swabbing/post firing. The breech block is just visible.

And today I picked up some laser cut parts from the cutter. (JR Laser, Geelong)

Minimal cleanup was required on the 6 and 8mm thick parts. Some extra machining is required. But the 25mm thick part has some problems. It is a little undersize. Apparently caused by heat expansion of the steel during cutting. I have not yet decided what to do about this problem. I might have to get it re-made 2-3% bigger. Or I might remake it myself on the CNC mill.

Next Build? A Crane?

Still a fair bit of machining to finish the Armstrong 110pr breech loader.

And I was wondering whether I should spend my time fixing a very run down house rather than making model machines.

I know what I would prefer to spend my time on. And I do NOT like climbing up ladders any more. Age 72!

But SWMBO is not well. 25% of the way through chemotherapy. She is coping well. I am OK. Just.

And, I had decided that the Armstrong 110pr would be my last model build (well, not counting plastic models which I can assemble in front of the TV.)

….But, when I saw these drawings of an 1899 steam driven wharf crane, drawn into plans by Julius deWaal, I am sorely tempted.

A 1:12.7 model would be about a meter high. Contains a boiler (which would require certification), a twin cylinder double acting steam engine, THOUSANDS of rivets, many gears including bevel gears.

But, is it not beautiful, magnificent. And there are excellent plans (thanks again Julius deWaal!), and best of all, the original is less than an hour away from me by air, in Hobart Tasmania!

While I am waiting for some laser cut parts for the cannon, and tools from India, I MIGHT just start accumulating materials for this one.

Model Armstrong 110pr. Machining the Breech Chamber.

The exterior shape of the barrel is one of the final steps. The basic cylindrical shape is retained as long as possible to facilitate work holding in the milling vice. Here the axes are marked. The rifling can be seen.
The exterior final shape of the breech has been finish turned prior to milling the breech block cavity.
The rectangular cavity is up to 20mm deep. 24mm x 16mm. I started by drilling corner holes, then used a new 8mm end mill taking 4mm deep cuts.
After the 8mm endmill, the walls were tidied with a 6mm endmill. Have I mentioned before that I love CNC.
This is the first time that I have tilted the milling head. It was easy, and quite predictable and steady. 20º.
Not a perfect finish, but it will do. Maybe a bit more filing. The breech piece fits down there, and the breech screw locks the breech piece against the end of the bore.

Model Yamato painting- 2 (finished, almost)

A few photos of painting the model Yamato. I used Tamiya paints. Spray cans for the large areas- and hand brushes for the small ones.

The entire hull was primed, then the water line masked.
Masking tape to define the waterline, then a quick, careful spray with dull red. Lovely colour. Not dull at all.

Then removed the masking tape and applied some more tape over the red. Painted the top half of the hull, and the other modules, “battleship grey”. Then glued the modules together.

The wooden decking is laser cut and the individual planks are laser marked. Incredibly thin… not measured but maybe 0.25mm. And have a paper backing which when removed exposes the adhesive. The pieces are extremely accurate for the model, fitting into their spaces and around winches, guns etc. NO trimming was required. My only issue was that some areas required extra adhesive. I used Tamiya Ultra Thin Glue, and it worked well. Great care was required in positioning the sheets.
And some hand painting of small details. The superstructure tower, funnel, 5″ guns, anti-aircraft cannons, and main aerial. The wooden decking was then applied. See how accurately it fitted around all of the deck machinery and guns…
A close up of the wooden decking detail. Very impressive! And not expensive. Cost about $AUD20 including postage.
The fore and aft flag posts are very fine, and inclined to catch in clothing and break. After repairing them at least 10 times, I reinforced them. Can you see the dressmaking pin? The cavity to the left of my finger is the lifting well for the aircraft, leading to the hangar.


The end result….

Superb shape! And this photo reveals that at least 95% of the ship volume is within the hull.
9 18″ guns in 3 barbettes. The wings on the barbettes are range finders. The decks around the guns were kept as clear as possible because the blast from the 18″ guns was huge. 20kg/cm^2
Yamato could carry up to 8 spotter planes. Launched by catapult, and picked up by the crane at the stern.

The model is complete, except for the flags and aerial cables. Took me a week to make and paint. I really enjoyed the build. And I really like the model. It was not an easy build, but the real credit goes to the people who designed and made the kit. It is truly impressive how well everything fitted together.

Now. Where to put it? And how to keep it dust free?

Yamato-Painting1; Restoring an old Westcott 6″ wrench.

The 1:350 Yamato model is made of plastic. Mostly Polystyrene, but also a small amount of ABS. Different glues required for each type of plastic. Both types will hold the parts in a minute or so, but several hours are required for rigid holding.

There are 17 different colours specified, which explains why the paints were so (unexpectedly) costly. Mostly IJN grey, and dull red, for the hull exterior, and wooden deck tan. I bought Tamiya spray cans for the dull red, IJN grey, and primer. The wooden deck tan was unavailable, so I bought some laser cut sheets of impossibly thin wood, already in the correct colour, and made for this particular model. Pictures later.

So I sprayed the primer coat.

The question was whether to make the entire model, then paint; or paint the individual parts on the sprue frames before assembly ; or something in between.

I thought that painting the entire model would be simplest, but some small parts and areas would be inaccessible, and the result would be messy.

Painting every component on the sprues would leave a bare cut area on every part which would need to be touched up later, so that did not appeal. Plus it would be very time consuming.

So I decided to make the ship in modules, and paint each module separately.

The painting modules….. the hull is just 2 colours, IJN grey, and dull red below the water line. Some masking will be required. The other modules will be painted individually. As seen, 99% of the gluing has been finished.
So today I applied the primer coat. The paint is touch dry in about 10-15″. I started with the underside of the hull, then turned it over, on the box as support, and painted the decks. The box was exactly the correct size to support the deck without damaging the tiny attachments.
Then the smaller modules. The alligator clip attached to a chopstick was a handy way of rotating the workpieces, and minimising painting my hand.
Still some small parts to be attached, but they will be different colours which is my reason for not attaching them before this. This is one of the 18″ gun barbettes.

Tomorrow I hope to start applying the final colours.

Painting is really NOT my thing. So to finish the day I spent some time restoring an old small Westcott adjusting wrench which had been given to me by a friend.

It has an interesting, appealing shape. Sadly abused, bending and breaking the jaws and bending the rather nicely curved handle. So my first step was to disassemble the parts. The moveable jaw had seized so I punched it out.
I tried to cold bend the fixed jaw but it would not move. So I used a hand hack saw to open up the crack, then bent the jaw back towards a right angle. 3 successive cuts and bends were required to get it back to 90º.
Then V’d the cut, almost to the box inner section. Then arc weld filled the V. It wont be as strong as the original, but will be OK for light applications.

Finally some time was spent grinding and sanding the weld flat, and filing the parts make them slide easily. It was still a bit sticky, so some “Gumption” was used to smooth the action. The handle was cold bent back into a nicely curved shape. I might get around to blackening the wrench by heating it and quenching in dirty sump oil.

Model Yamato

So far, glueing up the model has been interesting and a lot of fun. Look at the progress after 2 days….

The guns and superstructure are just sitting there. The components will be separated for painting.

The tools which I have found useful are lined up.

Alligator clip on a chop stick, rubber bands, Extra Thin Tamiya Glue for polystyrene plastic, flat non serrated small pliers, needle nose small pliers, safety razor blade, sharp side cutters which I have modified so the cutters are thin and very pointy, steel ruler used as a scraper, small fine file, fine sand paper, fine tweezers (actually from my microsurgery kit of 30-40 years ago), coarse strong tweezers, and utility knife. And of course an A2 cutting board, and Tamiya Instruction book which I have found to be accurate and very helpful.

The Extra Thin Tamiya Glue is very good. It sets in a couple of minutes so parts can be finger held in position. It is so thin that it tracks into small cracks by capillary action. And it is transparent. Time will tell how paint adheres to the glue.

The Tamiya parts are also very impressive. Beautiful smooth finish, minimal flashing which can be scraped off with a finger nail. And the parts fit together very accurately, for the most part. Rarely I had to use the razor blade to make parts fit together, and that was usually because I had missed a bit of the sprue when separating the parts from the sprue.

This was one of the first areas to be glued.
Large joins, like this foredeck to hull, were glued progressively, holding each bit with a rubber band. The deck has a bend, and I could not hold it in place with only my hands, but the rubber bands worked pretty well.

It was quite exciting to see the hull coming together.

Many of the parts are extremely small, and too light to feel. The fine tweezers are very handy for these. So far I have lost only one part after dropping it.

I am close to painting the components. I will use Tamiya spray cans, brush applied paints for tiny parts and fine lines, and possibly an air brush. I have been watching YouTube videos to pick up hints on the painting process. It was surprising to me just how many YT videos exist on the subject of painting model Yamatos.

Then the major components are glued together.

Then the smaller guns and other surface equipment will be glued on to the painted surfaces.

P.S. Another 1/2 day gluing up these tiny planes. One more to go.

These really tested my eyes and hand control. Cotton bud for scale.
This cheap Banggood LCD microscope was very useful. Only trouble was that it magnifies my shakes. (Mustool G1200)odel

A Book Review. And Consequences.

In common with many other males, (whoops. Possibly females as well, although I know of none.), I have long had a fascination with battleships. Of all eras from the ancient Greeks and Romans, Nelson’s, dreadnoughts, WW1 and WW2. Read the novels, made models from kits and from scratch. I have quite a library of books.

Recently, I purchased this book…

It was not cheap. But absolutely worth every cent. Available from various vendors. I got mine from Amazon.

336 pages. 350 colour views, including some original photographs, and lots of details. 1020 scale drawings of excellent quality. 43 pages of history and specifications. The bulk of the book is superb quality pictures and drawings.

These battleships, at 72,000 tons, were the largest ever constructed. And they mounted the biggest guns ever used on a battleship at 18.1″. Each of the 3 gun turrets weighed as much as a heavy destroyer, 2500 tons. They were 250 meters long, and 50 meters from keel to the top of the superstructure. Their 4 turbine engines drove the ships at 30knots/50kph. Each ship had 25,000 tons of armour, up to 560mm thick!!

“Awesome”, seems insufficient.

The Imperial Japanese Navy had them built to outgun the most powerful battleships of the US Navy and western powers. However they were dinosaurs, and both were sunk by aircraft. Neither fulfilled their intended role of fighting other battleships.

The book is divided into 4 sections….

Section 1: Introduction, Superbattleships and Summary of Service. 43pp.

Section 2: Primary Views. 25pp.

I cannot overstate the quality of the drawings. Just magnificent.

Section 3: The Drawings. Subdivded into general arrangements, Hull structure, Superstructure, Rig, Armaments, Fire Control, Fittings, Aircraft, Boats, Author’s Model. 252pp

18 pages are devoted to the 18.1″ guns.

Section 4: Yamato and Musashi at sea, Remains of Yamato and Musashi 12pp. The pictures “at sea” are computer constructions, using the author’s model, and incredibly convincing. Initially I took the pictures to be of the originals.

Both ships were sunk by massive US air power, with the loss in Yamato’s case of 90% of its crew of 3,300 sailors. Almost as sad, almost all of the original construction plans and details were destroyed by the IJN after the Japanese surrender.

So, if you have any interest in battleships, massive marine engineering, WW2 naval history, or ship modelling, this book is an absolute must.

Consequences??

After reading the text, and going through the pictures multiple times, and being captivated by the wonderful lines of the ships, I decided to make a model of Yamato. Kits vary from 1:1000, to 1:100, with the larger scales being in the thousands of dollars.

I made plastic assembly models when I was a kid, and once as an adult when I was laid up for 6 weeks after an injury (see later photo). In this case I settled on this kit. Tamiya is a well respected brand. The kit is 1:350 scale. Cost about $AUD150. I hope to interest a grandson to get involved.
The paints required cost almost as much as the Tamiya kit!
The ABS plastic components look excellent, with hardly any flashing, detailed instruction booklet. There is provision for batteries and remote controls, but I doubt that I will go that far. The hull is big! 751.5mm long.

The following is the only surviving plastic model of mine. Another ship with wonderful lines.

Cutty Sark. Even after blowing off most of the dust, it looks more like Shackleton’s “Endurance”. And needs some TLC.

A question to my readers….. would the progress of making the model Yamato be of any interest?

Rifling the Model Armstrong 110pr Cannon.

For reasons which I will not detail here, I am spending more time at home, and much less in my workshop. Work on the Armstrong 110 pr breech loader is progressing, slowly. However, the rifling is complete.

I detailed the rifling setup in a previous model build, but in case you missed it……

The barrel is held in a jig which is clamped to the CNC mill quill. The mill spindle is turned off, for obvious reasons.

The cutter protrudes from a 16mm shaft. The brass bush increases the diameter to 18mm to fit neatly into the bore. I should have remade the entire shaft with 18mm bright steel, but I thought that this modification would work with a lot less trouble. It did. Sort of. The cutter was 3mm wide, and I ground the actual tip to 0.9mm width.

The cutter is mounted to the CNC rotary table with an ER40 collet. The depth of cut is determined by the screw at right, and the maximum depth of cut set with the 2 locked nuts. The mirror is for inspecting the cuts which finished underneath and at rear.

The setup took several sessions to complete. I had previously drilled and D bit finished the bore, and drilled and cut a large thread to accept the breech screw. Then I turned the exterior of the barrel so it would fit the jig. It will be turned to its final shape in a future session.

I could not find actual specs for the twist, so I randomly decided on 90º. The cut started in the powder chamber and finished just beyond the muzzle. The rifling in the original started distal to the projectile chamber, but I had to ignore that due to limitations of my setup in accessing the adjusting screw. The powder chamber and projectile chamber were slightly bigger than the bore in the original, so I might be able to machine away the unwanted rifling in those areas in my model.

30 rifling grooves in the model. The original had 76. But in an 18mm bore the 30 cuts are only 0.9mm wide, and that was as fine as I was prepared to grind the cutter. The cuts are about 0.25mm deep, which is to scale. I will polish the bore later.

Armstrong 110pr RBL -4. Tapping the breech.

This is the breech piece. From a 1.25″ high tensile bolt, with an 18mm hole drilled and reamed. The thread is 8tpi. An unusual pitch for the size. 60º form. Further shaping of the ends to come, but I decided to make the female thread in the breech first.
I cut the thread on the lathe manually, but the HSS cutter tip broke and I had to regrind it after the thread had already started to form. As you can see, the reset cutter position was a bit out. But I corrected the position and pressed on. How do the experts reposition a threading cutter? As per the original threads, I left flats in the female floors, and ground off the peaks of the male thread. (someone can correct my terminology here…)
Anyway, the breech piece threads in snugly and nicely. Quite tight but screws in by hand.
…and an 18mm silver steel rod fits well into the breech piece and into the bore of the barrel, so the threads are well aligned.

Despite the errors, this thread has worked out pretty well. I have learned a lot, and I reckon that the next one will be better.

The breech piece will next act as a tailstock centre for turning the exterior of the barrel between centres, after removal of the fixed steady.

Armstrong 110pr Cannon Model-3

This project is progressing slowly. Other issues are taking time at present.

There are 3 major components on these cannons…. the traversing platform, the wooden carriage, and the iron barrel. And a number of smaller components… the compressor (the recoil suppressor), the elevating mechanism (Smith’s screw), the sights, and various rope eyes.

I usually have something in mind to work on when I enter my workshop, but sometimes I just proceed where the mood steers me. I have actually been working on all 3 of the major components, with most progress on the traversing platform, which explains why the posts have been rather fragmented. Most of the work so far has been woodworking, but recently I had an urge to do some metalworking. So I made a start on the barrel.

The first step was to buy and cut to length the 1020 steel shaft. Then the piece was mounted in the 4 jaw chuck, and dialled within 0.05mm at the chuck. The tailstock end was supported in the fixed steady, and also dialled in. I was not trying for perfection because it is a case of time and diminishing returns, and straightness of the bore and concentricity between the bore and the exterior of the barrel are the main concerns.

So, the next step was to drill the bore to 16mm, using the extended drill bit which I had fabricated for the previous cannon, after centre drilling. The resulting hole was 305mm long, appeared to be straight, and just a bit rough.

Drilling the 16 x 305mm hole took 15″. I touched up the drill bit cutting edges with a diamond lap, and cleared the swarf every 10mm or so. Plenty of cutting fluid used.

I wanted a final bore of 18mm diameter. I have an 18mm reamer, but only 120 mm long, so I made an extension rod to fit the Morse 3 driving tab. But first I had to drill the bore closer to 18mm. So I made a D bit from undersize 18mm drill rod.

The silver steel / drill rod is 17.94mm diameter. The flat is milled, removing 8.94mm and leaving ~9.0mm. The cutting end was hardened by heating to cherry red , then quenching in oil. It was still able to be filed, so not hard enough, so I repeated the heat-quench cycle, using a water quench, and that worked well.
Using the belt sander to give some side and rear relief. Later I added a chamfer to the cutting corner (see next photo).
Cutting corner on the left.
The “business end” as requested by John Marshall. This is after cutting through 305mm of 1020 steel, and it needs another touch up with the diamond lap. initially I used the D bit as shown on the belt sander above, but the cut improved after the bevel was added with relief to the cutting corner. The only purpose for the recess is to accumulate swarf during the cutting process. But the recess fills quickly and it needed cleaning out every 5-10mm of drilling depth.
The D bit was held in a 40ER collet in the tailstock. Plenty of cutting fluid was used. The chips were cleared every 5mm of cut. The D bit was sharpened 3-4 times during the process using a diamond lap. Enlarging the bore to 17.95mm with the D bit took 15min.
This was taken after using the D bit. The surface finish was improved further after passing the reamer. I am not concerned by the rough appearance at this end because it will be machined out to 28mm for a depth of 50mm to accomodate the breech screw and breech plug.
The breech screw is shown in drawings of the era as a buttress thread, with a pitch of approximately 1.25″. I have some 1.25″ diameter threaded rod, category H2, with a pitch of 1/8″ which at scale 1:10, is very close to the original, although not buttress profile. The drawing is very close to full size for the model. I drilled, D drilled and reamed the through hole, and am considering how I will cut the thread into the breech of the barrel. Still pondering whether to try to cut a buttress thread…

And the traversing platform now has the metal surface strips screwed into position..

The 1mm thick stainless steel strips had been laser cut and 2mm holes laser drilled. I had to countersink the holes so the screw heads were at or below the surface, so provide a smooth surface for the carriage slides and trucks (wheels). The countersink tool is carbide. I wanted a smooth flat surface to work on, so used a fly cutter on the wood to produce such. The counter sink bit self centres well.
The screws are 1.6mm diameter. In that size I had to settle for Phillips heads rather than simple slotted. The larger circular cutouts are for the wheel posts, yet to be made.

Armstrong 110pr Breech Loader-2

Having commenced building a 1:10 scale model of this gun on a wooden carriage and traversing platform, I am also finding information about its history. First the build progress….

Glueing the traversing platform pieces. And a 4mm long series drill bit.

Gluing required some planning. The brass stops rebates were tricky to make last time because the platform was already fully assembled. So this time I made the rebates and installed the stops prior to gluing up.

Then there is the matter of the long, 4mm, holes across the multiple pieces of the platform, which is up to 152mm wide. Wood is not uniform like steel or aluminium, and deep drilling wood with small diameter drill bits usually leads to wandering crooked holes. So I measured and drilled each piece separately, prior to assembly. A tricky and exacting process. All except for the outside pieces shown being clamped above. They were drilled, one side at a time, after that side was glued, using the existing holes as a drill guide. I was happy with the results of the drilling and gluing.

Cutting out the carriage cheeks with a 6mm endmill. The workpiece is screwed to the sacrificial base piece with large woodscrews (not visible), then the required holes for the model are drilled through workpiece and sacrificial base and bolts are inserted. These bolts stop the workpiece from moving in the final stages of cutting the part free. The carriage cheeks will not be parallel in the final assembly, being narrower at the rear than the front, and the holes will need to be modified at that stage, so I have drilled them undersize at this time. Same goes for the trunnion cut outs.
Glued and drilled traversing platform (one of 2); laser cut 1mm stainless steel strips ready for attachment (AUD$55 including material. Probably saved me a day and more accurate than I would have managed), and CNC cut carriage cheeks, straight off the mill. Recycled Victorian Mountain Ash floor boards).

Not so much workshop time lately due to family factors, so I have been reading and searching references. And thinking about how to machine the barrel. Important to get the sequences right. And to have available the correct tools.

A is the screw which compresses the breech block E into the copper seals F and H, after the projectile and charge have been loaded through the breech. B is the weighted handle which operates the screw. C is the breech coil. D and J are further coils. K is the trunnion piece which was forged including the trunnions.

The originals were made using the Woolwich “coil” system, in which components of the barrel were made into various sized and shaped cylinders by winding white hot strips of iron or steel around a mandrel, then hammer welded into a single fused mass. The various cylinders were then accurately turned on large lathes into the final pieces which were heat shrunk together, and finally furnace welded. The Armstrong 110pr had 7 such major pieces. Only the innermost barrel cylinder was steel.

There were 2 barrel designs of the 110pr guns. The above diagram is the 72cwt version, which was 2″ shorter than the 82cwt version. The latter has more taper to the chase of the barrel, and will probably be the one which I model.

The 2 types of 110pr barrels. You can see my metric conversions of the dimensions. And a few dimensions scaled off the drawing. I think that I will make the 82cwt version.

I will not be making my model using the coil method, but I am probably going to make the trunnion ring with trunnions as a separate item, and shrink it onto the barrel, along the lines as described by jefenry.com. Still thinking about those big asymmetric double start threads on the breech screw. I have a high tensile 32mm bolt and nut which I am considering using.

The scaled bore should be 17.78mm. I will approximate that to 18mm. Will need to extend a 17.7mm drill bit, and to make an 18mm D bit from silver steel. Jefenry welded an extension to an adjustable reamer to finish his bore. I will possibly use that technique also.

Model Armstrong 110pr RBL – Early Steps.

So. Having made the decision to make a model rifled breech loader, Armstrong gun, on a wooden sliding carriage and wooden traversing platform, I gathered my references. A lot of these guns were made, 959 in use in 1878. Many on wooden carriages, some on iron carriages. They were used in several wars, and I will be delving into the history. Examples of the guns exist in quite a few countries including UK, USA, Canada, and Australia. There are references in Wikipedia, and several artillery books of the era (1860-1890). Various models have been made and documented, including good descriptions, particularly by jefenry.com.

I have several reasonable scale drawings, including some kindly sent by jefenry. (Thanks again Jeff!)

This is the 110pr breech loader on a sliding carriage, and standard traversing platform.

In the drawing above, the traversing platform is identical to the ones under the 80pr Armstrong RML’s which I recently modelled, so my previous experience will be useful for the current build. The carriage for the 110pr RBL is similar, but not identical. The barrel itself will be quite different, and will be the main challenge in the current build. Apart from the breech block, and breech seal, there are 76 (!) rifling grooves, compared to 3 rifling grooves in the RML. I am already thinking that I will be reducing the number of grooves, to maybe 28.

Another handy resource which I found during my Internet searches of Armstrong 110pr’s, is ETSY.com, a Canadian site, where the Armstrong 110pr has been CAD drawn in very fine detail, and available for $AUD34. The drawings are not perfect in every detail, but even so I rate them as very good. Only available as Fusion 360 files, but Fusion 360 is available free of charge for hobbyists, with some restrictions relating to file numbers and some features.

The link to the Canadian site is: https://www.etsy.com/ca/listing/702320886/3d-model-british-armstrong-rbl-110-pr-7

And another old drawing of the barrel details.

Yesterday I purchased a lump of 1020 shaft, 1270mm long. I only required 305mm, but the supplier was unable to cut it for 3 days, so I took the whole piece. A burly worker picked it up as if it was made of balsa wood, and put it in my car. I struggled to unload it at the other end. 40+kg/ 90lb.

Wanting to get started, I cut off two 306mm billets.

…and weighed the 306mm piece…

10+kg

The next step for the barrel is to rough drill the bore. I have an extended 16mm drill bit from the previous model, but will have to modify a 17.75mm bit and extend an 18mm reamer or make a long 18mm D bit, before I can proceed. So instead, today, I made a start on the traversing platform.

Actually, I have decided to make one for myself, as well as the intended gift.

Having made a few errors in the machining sequences last time, hopefully I can avoid the mistakes this time. Also, with multiples of some components, such as wheel brackets, and rope rings, I will be casting some of these in bronze, and getting laser cut parts for others such as the metal slides.

The original Armstrong barrels were constructed in multiple pieces which were shrunk together, using the “coil” method to construct the pieces. The trunnions were on a separate ring which was forged, then machined to final shape, then shrunk into position. I am considering machining the model trunnion ring separately, and shrinking it into position, but the rest of the model barrel will be turned from a solid piece of 1020 steel.

Another Model Cannon?

I had thought that the 1:10 scale model Armstrong 80pr rifled muzzle loader would be the last cannon which I would make. It is currently being given finishing coatings to the woodwork. Later this year it will be given as a gift to a family member.

To be honest, having made five 1:10 scale model blackpowder cannons, I am ready to move back to my first modelling passion, which is steam engines. I had no real interest in weapons or guns or artillery, except as a means of increasing my understanding of history, specifically military history. I have no interest in firing guns, although I must admit to an illicit satisfaction in watching You Tube videos from USA of cannon modellers who can actually fire their creations.

My interest in cannons started when, as a newbie in CNC machining, and looking around for a project to use my newly acquired CNC lathe in 2015, I made a model long gun.

1:10 scale models of a 1779 24 pounder long gun, and 1804 carronade of the same bore. Making them was interesting, and the associated history was totally engrossing.
Then the Ottoman cannon of 1465, again 1:10 scale, over 500mm long.

The Armstrong 80pr muzzle loader, scaled from the originals at Port Fairy and Warrnambool.
Another Armstrong RML 80pr. I kept this one.

And the most recent Rifled Muzzle loader, the same 80pr Armstrong Barrel, on a Dwarf carriage, and wooden traversing platform.

Almost but not quite completely finished in this photo. Since then it has been cleaned, stained, and lacquered.

I truly thought that this would be the final cannon which I would model. So I could get back to my model steam engines.

Like this one from 2-3 years ago, now gracing our kitchen, with decorations by SWMBO.

Trevithick dredger engine and boiler, of about 1805. 1:8 scale. The possum and the budgerigar are not real. Neither are the two T. Rex’s fighting on the boiler.

BUT….then my eldest daughter, who has absolutely NO interest in cannons, asked ” are you going to make a cannon for me?” I must point out that this daughter rescues injured animals and takes them to her vet, is vegan, the most pacifistic and socially conscious person that I know. I questioned why she would want a model cannon. “I just do” she replied.

Oh well. I guess that I will be making one final model cannon.

I spent a day searching my books, Google Images, Wikipedia for a cannon which would look interesting as a model, be interesting for me to make, and for which some plans or drawings are available. I offered my daughter the choice of my existing models, but no, she wanted one built just for her.

Then I thought of jefenry, my reader from the USA, who has made several model cannons, including one which intrigued me when I first saw his pictures and videos several years ago. It is a 1:9 scale Armstrong rifled breech loader, 110pr, of 1861. One of the first breech loaders of relatively modern times. (Breech loading cannons have been around since medieval times, but they were less reliable than muzzle loaders, more inclined to explode and kill their own gunners.). The Armstrong 110 pr RBL saw action in several wars, including against Japan, the NZ Maoris. It was the largest cannon on HMS Warrior, but was replaced by the more reliable muzzle loaders.

So that is what I will model for my daughter. An Armstrong 110pr, rifled breech loader, on a dwarf carriage and wooden traversing carriage. Here are some pictures.

110pr Armstrong at Fort Henry, Canada. I presume that the traversing carriage is a reconstruction.
And the 1:9 model of a naval version of the gun, which was made by jefenry. Check out the making of the cannon, including rifling, at jefenry.com and watch his video of firing the cannon at https://youtu.be/m3pC0eDvs90

So, my plan is to make a 1:10 model of the barrel, on a carriage and traversing platform like the Fort Henry example above. Not sure how much of the build will be featured on this blog. I am again very close to my WordPress.com memory limit.

Gunners Side Platforms

These daily posts might be becoming a bit tedious but you need to realise that I write them for my own diarising purposes as well as entertaining yous.

First today, I deepened the countersinks on the carriage stops which I had installed yesterday, and filed the bracket surfaces until the carriage showed no signs of catching on high spots. Then reassembled all of the bits in the vicinity.

I had machined some hardwood (Australian Mountain Ash, a close grained, hard, stable, pale hardwood) for the side steps, and today I made the brackets to support the side steps.

There are side steps on both sides. The one not visible is smaller. R1 R2 and R3 are the steel supports.

But, when I examined the steps today, I decided to remake the side steps, using the dark red hardwood Jarrah, the same as the rear platform.

The Jarrah side steps. They will age to a dark red colour, like the rear platform. The grey desk mat is A2, to give you an idea of the scale.

The steel brackets were cut from 50mmx25mmx1.5mm rectangular section tube.

Cutting the RSS.
Bolted to the side steps. They look a bit rough at this magnification. The lip at the top is cold bent.
The U bolts are bent brass rod. I intended to Loctite them into the drilled holes, but they needed to be hammered home, so I think that glue will be unnecessary. (I made 2 extra)

So, I think that those are the final parts to be made for this model. Now I need to decide about finishing the wooden surfaces. At this stage I am thinking of a dark wood stain, then a satin finish with a wood oil.

Traversing Platform Floor, and Carriage Recoil Stops.

Firstly some woodworking to make the platform floor. Basic machining, drilling and screwing.

Quite pleasant to do some basic cutting on the bandsaw and thicknessing on the mill. HSS metal mills give a good finish on hardwood. It was finished quickly, and went so well that I proceeded to a task which I had been putting off, because I knew that it would be very difficult.

I made the carriage recoil stops, and installed them.

The problem was that the platform had been previously assembled, including gluing of the joints. And I was not going to break those joints for anything.

The recoilatop is on the inside of the platform slides, at the rear. Shown here above the bollard. It is recessed into the slide so only the actual iron stop is above the surface. Also, it is underneath the bracket which supports the gunner’s rear platform.

The stop bracket is about 30mm x 6mm x 2mm, and the stop protrudes about 5mm further. So the first question was how to make the rebate. The distance between the slides is only 53mm. Not much space to use chisels. And end mills could not be used. The metal surface of the slides is glued and screwed to the slides, so removing those was not an option either. I should have made the rebates BEFORE I glued up the platform. Oh well….

This is the setup which I used….

I bought some Woodruff cutters and T slot cutters at a sale some years ago. So I cut the slots with one of those. The cutter worked well, but it left sloping ends. One of the ends is hidden behind a bracket, but the other one is visible. Used the inspection mirror to watch the milling on the near slide.

So how to square up those ends. Not enough room to get a chisel into that space. Still wondering, I made the actual stops.
Making the stops involved some basic milling and silver soldering. The steel nut got a bit chewed up during the slotting. It will not be visible in the final assembly.

Then, rather than squaring up the recess, I rounded the hidden corner of the stop bracket. Easy!

Drilled the holes in the stop brackets for the screws, fitted the stops into position. Now, how to drill the holes in the wooden slides for the screws? The holes in the wood were only 1.4mm diameter. And a 1.4mm drill bit is not long enough for the drill chuck to miss the other slide. To avoid the other slide the hole would be excessively angled.

So I used another trick which I have used previously. I silver soldered the drill bit into some fine (2mm OD) copper pipe….

1.4mm, 1.6mm, and 2mm drill bits given substantial extensions. I used copper for the small sizes because I had some suitably sized pipe. I had drilled the hole in the brass rod for the 2mm extension for another model.
The extension meant that there was only slight angulation of the hole when drilled with a battery drill.

I will enlarge the countersink on the stops to bury the screws deeper, then file the screws flush with the stop surface. I doubt that the bit of angulation will ever be noticed. I used steel screws, because a brass one snapped off and I had to drill through the remnants. The steel screws are slightly bigger than intended, but not excessively. I had removed the gunners platform to improve the access. The area will look tidier when fully reassembled.

I am very glad that particular task is all but finished!!

ps. I have called them “stops” but that is probably not the correct term. The recoil of the carriage is reduced by the 5º slope of the slides and the braking from the compressor. The “stops” (or whatever they are called) are the final impediment in limiting the recoil of the carriage and its barrel.

Carriage Wheels -3

Today I milled the rebates which the wheel brackets fit into. Only 1mm deep and at an angle of 15º to the base line. It went fairly well, but when I reversed the milling pattern for the reverse sides, It went a bit askew by about 0.5mm. Not much, but enough to be noticeable, so I filled the defect with wood putty.

Then I milled the 3º chamfer in the wheel brackets. Straight forward process.

Finally, with the brackets sitting correctly in their rebates I wondered how to make the bracket retaining bolts, and the wheel axle shaft.

The bolts have dome heads.

I prefer to use stainless or brass bolts, but none come with dome heads, so I considered various options. I chose to use a method which I have used previously.

I selected some 3mm stainless cap screws, and filled the head with 50% silver solder.

I needed 4 dome head bolts for the brackets, so made 6, just in case.
at top is the lathe ER40 collet, which is holding a smaller ER16 check and collet, then a 5mm screw for form turning with the milling rounding over bit. It all worked well, with only 2 failures. In the above photo the turning has not quite fully formed the hemispherical head.

…And used a rounding over milling bit, held in the toolpost, to round over the capscrew head and its silver solder filling. The first screw bent during the form turning, so I placed them deeper in the ER collet chuck. A later one broke, so I slowed my feed rate. I ended up with 4 bolts.

I did the same with some bolts for the axles, but they are fully threaded, so this will be a temporary solution until I can make more suitable axles.

But you can see how the brackets, wheels, bolts and nuts will appear.

You will notice the filled hole in the carriage cheek. That was a mistake, but rather than start the cheeks from scratch again, I chose to fill the holes. They will be almost invisible when the cheeks are finished, I hope.

The axles are temporary. I am happy with the brackets.
I am showing the best side here. Looks OK?

Carriage Wheels-2

The Armstrong 80pr rifled muzzle loader at Hopetoun Gardens, Elsternwick, Victoria. One of two.
On the Elsternwick guns the slides have been covered with sheet metal covers to protect them.

The carriage wheels are at the front of the carriage. They do not actually contact the slides unless the rear of the carriage is levered up a few millimetres, to assist with rolling the gun down to the firing position.

They are constructed of bronze.

On my model, the gap between the wheels and the slide would be about 0.3mm.

Today I attached the wheel brackets to the carriage cheeks (the sides of the carriage).

I had deliberately made them with a slightly large diameter, knowing that I would need to reduce the diameters after they had been fitted.

This is how I reduced the diameters…..

…on a belt sander, holding the oiled shaft in my fingers and using my thumbnail to hold the wheels in position. After a few seconds sanding, and being careful not to sand my fingers, I tried the wheels on the carriage, rolling it up and down the slide. That was repeated multiple times until the wheels were just clear of the metal slides.

The single axle will be replaced by more authentic appearing separate axles with dome heads and pins. The brackets will be let into rebates in the carriage cheeks, and tapered in their upper halves.

Carriage Wheels

The Armstrong 80pr cannon on the dwarf carriage and wooden traversing platform, slides wood on metal slides. But, when the carriage and its heavy barrel (4+ tons) are returned to the firing position, there are two small bronze wheels to make the return easier.

Two strong gunners lever the rear of the carriage and barrel slightly, so the two small wheels at the front of the carriage take some of the weight, and the carriage runs forward. In fact, the return was a bit uncontrolled, so a rope was added to the rear of the carriage, thrown around the bollard at the rear of the slide, and a third gunner added some control to the return.

Today I made the 1:10 scale wheels. They are 20mm diameter, and 10mm wide. 13mm wide if the hubs are included. I spent a couple of hours with the design. And another couple experimenting with various CNC processes. Not many photos of all of this I am afraid. I learned some new V Carve Pro commands, including nesting commands using the same milling cutter, but there was some trial and error. The first two wheels took a couple of hours. The final two took only 30″.

The original wheels, and brackets.
The brackets are partially recessed into the carriage cheeks. The wheels do not contact the slides unless the rear of the carriage is levered up slightly.
A wheel, and brackets ready to be fitted to the carriage. The dished section was milled with a ball nose cutter.
I will fit them next workshop session. The brackets need a lengthy chamfer first, as per the second photograph.

NB. these parts are not finished. Sharp edges remain. I will probably put them in the gemstone tumbler to smooth the edges.

Wooden Compressor-3

To remind us what is being 1:10 scale modelled.

Today I CNC milled the cams. And silver soldered them to the bearings.

The same process as making the bearings in the previous post. But much smaller.
Silver soldered. Hebel base and brass block at rear to stop the parts blowing away.
Magnified +++.
The handle was cnc’d, but I made a mistake with the dimensions, so made another one. That is easily done with CNC. The tabs are cut with side cutters.
Pins are fixed in the 4 holes around the pivot, and a “rope” 2mm diameter in the end hole. I will turn the handle over to hide the distal ding. The marks are the limits of handle travel, limited by the carriage transoms.

PS. A few days later. In a fit of perfectionistic idiocy I removed the bronze cams, and replaced them with steel ones. The originals were iron. The pins which pushed on the cams were also steel. That took about 3 hours, but now I can sleep easy.

And by the way, the compressor was working perfectly when finished. But a few days later, with a change in the weather, it is not applying enough pressure to the slides. That is the problem with articles made from wood….. they expand in humid weather, and shrink in dry weather. Dimensions changes of 3% are common, across the grain. It was probably one reason the wooden compressors were abandoned in favour of Elsworth iron compressors, and hydraulic mechanisms.

Wooden Compressor -2, and Smith’s Screw.

Making scale model components probably takes as much time as making full size ones. Well, with some exceptions. In each part of the compressor for example, there are as many measuring, set-up and machining actions in the model as in the full size part. Finding dropped tiny parts would take as much time as the (considerable) manhandling of the heavy full size ones IMO.

Yesterday for example, I spent about 3 hours deciding how to attach the compressor support pieces, cutting, machining, drilling and tapping the holes, then fitting them.

I use brass or bronze or stainless steel wherever possible. Not always the same as the original, but I don’t want my miniature to end up in the same condition as the originals in another 150 years. The brass tabs were placed as close as possible to the corners, but avoiding the long bolts holding the leaves together.
The underside of the compressor. 10BA bolts. Wood gets grubby in the workshop. It will require a good solvent cleanup before finishing.
To demonstrate the compressor location. It sits on the metal slides, and between the cheeks and cross pieces (transoms) of the carriage.
The Smith’s Elevating Screw is finally complete. Here showing the pins which engage with the gear to turn the screw. The handle spins freely on the screw shaft. The hemispherical top sits in a corresponding hole in the bed plate. I am satisfied with this interpretation of the limited information available about the Smith’s Screw.

Wooden Compressor

Another boring cannon post.

A very pleasant drive to Warrnambool yesterday, and re-inspection of the very rare compressor which was the recoil arrestor for the LowMoor 68pr cannon. And probably for all guns on the same carriage and platform, including the Armstrong 80pr RML’s at Elsternwick, Queenscliff, etc which I am currently modelling.

This is the 1861 compressor. 2 elm wood pieces, plus a repair on the right, all splits, cracks, rot and rust, and rather fragile. 4″ thick. Possibly the only one of its type still in existence. The central bronze elliptical bearing shell halves are in good condition. The iron pieces riveted to the bearing shells are rusted, but fairly intact. The rectangular pieces in the corners rest on the inclined platform slides. The central iron presumed elliptical post and its handle are missing.

I wanted to closely examine the iron riveted pieces closely to check my theory that the short straight sections are the parts which acted as the cams to close the gap between wooden leaves and release the friction from the braking action. Unfortunately the rust concealed any such evidence. But I still believe that was the purpose of these iron pieces.

So, today, I commenced making a 1:10 scale model of the compressor to fit to my miniature cannon.

The bronze bearings and attached iron cams protrude above the surface of the wooden leaves.

At 1:10 scale the bronze bearings would be less than 1mm thick. How to make them?

I CNC milled them from some gunmetal hex bar, then parted them from the bar in the lathe. I had previously made the wood leaves, and CNC’d the elliptical hole to fit the bearings. I don’t have any elliptical drill bits.
… and they fitted nicely. The original bearings were screwed to the wood leaves. I intend to use Loctite. The originals were made of elm. I used a close grained Victorian Mountain Ash.

I milled the steel elliptical post from silver steel. Yes, CNC’d.

Steel post, threaded to eventually fasten the handle with pins to move the cam pieces. Handle not yet made.
The pieces all fit well. The screw is temporary.

Another workshop session require to make the iron cams and the handle with pins.

Fitting the Ring Bronze/brass to wood

This rope eye is 17mm high, 18mm long, 2mm thick.

After milling the rebates in the wood, I attached the bracket with the brass screws, and sanded them flat with the surfaces. Most of the strain will be on the steel screws. The brass screws are screwed and Loctited into place.

Then drilled and tapped the wood for the BA10 stainless steel bolts. It is fairly close to the original fastening method.

It took 4+ hours.

A short post. Tomorrow I am visiting the Flagstaff Hill Museum at Warrnambool, 2.5 hrs each way, to get some final details about the wooden recoil brake, the “compressor”. There is a problem with my CAD drawing of the compressor, and I am hoping that close inspection and measurements will answer my query. I will be accompanied by my expert friend Stuart for some extra perspective. The compressor will be the final substantial component to make for this model.

Silver Soldering. Another Method of Parts Positioning.

This is one of the few parts required to finish the model Armstrong 80pr RML cannon on a wooden carriage and traversing platform.

It is the ring which is attached to the rear of the carriage, used to control the descent of the carriage and barrel down the slide to the firing position, with a rope attached to the ring. The bracket is buried within the rear transom, and extends underneath the transom with more screws and bolts.
I cut the bracket pieces from 2mm flat brass strip, using a 3mm diameter endmill.

The issue in silver soldering the pieces together was that they are quite small, about the size of my little fingernail, joined at an 95º angle, with the ring also soldered in place in the same heating session. And I did not want solder getting into those 1.6mm diameter holes.

So I screwed the angle pieces to a block of hardwood which had a 95º angle, having fluxed the edges carefully to exclude the flux from the tiny holes. I would have added typists white-out if I could have found it.

I knew that the wood would catch on fire with the soldering torch, but hoped that it would retain its basic shape until the solder solidified. The steel on top was to hold the ring in position during soldering. If the method did not work I figured that I could make an aluminium shape to replace the wood.

After soldering, I put out the fire by dunking the assembly in a bucket of water.

And it cleaned up quite well. Now to carve rebates in the transom so the bracket sits flush with the wood surfaces.

The circular cutout is to allow the end of the Smith’s Screw to protrude under the transom.

Not much to show for several hours in the workshop, but it’s better than working. And best of all the method was successful.

Smith’s Elevating Screw -4 (hopefully final)

Another hot summer day today, so I arrived at my workshop early, before the heat set in.

First I drilled a 1.5mm hole through the Smith’s screw yoke and bracket, for the pin which completes the hinge mechanism which engages and disengages the screw handle. Sounds simple? Well, actually, my intention was insert a 1.0 mm pin, but the first drill bit broke. Now why didn’t I make that sensitive drill press when I first considered it?

So I had to disassemble the parts, and grub and poke around with a fine tungsten probe until all of the bits were out. Then set it up and drill it again. Used a 10BA bolt and nut as the hinge pin.

Then silver soldered some 1mm old drill bits into the previously drilled pin holes as the driving pins for the screw gear.

Parts fluxed, ready for heat and silver solder. I use 50% silver, with cadmium for these tiny parts. After soldering, a quench in water, brief soak in sulphuric acid to remove any remaining flux, another water wash, then the drill bits are cut to length, and tidied up. Why did I use drill bits? Because they were the only drill rod/silver steel which I had in this diameter, and it is a good use for blunt drill bits.

By this time the day was really heating up.

So, I threaded at 2.5mm some 3mm brass rod, then heated the sections where I needed to apply the bends, and made the handle. Also form turned the hemispherical head using a 2mm radius rounding over milling cutter on the lathe as described in a recent post.

The threaded post length might need to be adjusted, because I made it slightly longer than thought necessary. I have some spare length at both ends if necessary to adjust.

In position. It works even though I still need to fix the gear to the threaded post, and fix the truncated cone at the top to the post. I intend to use Loctite.
and I have yet to machine a hemispherical cavity to the underside of the iron (brass actually) bed.

Smith’s Screw -3.

Another half day workshop session saw some more small parts made for the Smith’s Elevating Screw at ~1:10 scale. As close to 1:10 scale as possible, but I decided to make the parts about 20% bigger than the dimensions I scaled off the poor quality drawing, to fit with small drill bits and end mills in the tiny end of the range. The smallest end mill which I used was 1.5mm diameter!

CNC Drilling the gullets in the gear with a 1.6mm drill bit, after turning the OD of 15.9mm. I made 2 of these parts, just in case.

This is the gear after completing the gullets with the 1.5mm end mill. 3000rpm, 0.5mm depth of cut, 30mm/min feed rate. (metal working is not great for hand beauty)

The Smith’s Screw square thread, yet to have a hemispherical head turned after sawing off the excess length, the brass half cylinder nut, the gear, the yoke and the shaft bracket. A hinge pin will be inserted first, then some relieving of the hinge edges. The yoke and shaft bracket were CNC’d from 3.5mm brass plate.
and a handle to be added, and a restraining collar. Oh, and the 3 steel driving pins to be silver soldered in the yoke holes.

One more session should see the Smith’s Elevating Screw completed.

Did you notice that I have modified 6 details since drawing this?

AnyCubic Mono X Magnetic base

Unless you have one of these resin printers I suggest that you close this post and look at something of greater interest.

One problem which I encountered with my AnyCubic Mono X 3D printer, was that it was often difficult to separate the print from the base without damaging the print due to excessive adhesion. I have changed the print settings to reduce the initial layer UV exposures to 16 seconds which has helped somewhat, but I decided to try using a magnetic plate. A magnetic plate worked really well on my filament printer, and I was hoping for a similar result on the resin printer.

So I purchased another aluminium base, and a 3M stick on magnetic surface. I could have used the original base, but that would have committed me to using only the magnetic plate surface. Having a second base leaves my options open.

The base which I purchased looked similar to the original, but I noticed that it was not flat. In fact it had a concavity of approximately 0.25mm over its length. Also, it was missing the rather distinctive AnyCubic patterning in the aluminium surface which I think was a reason for the high adhesiveness of the original plate.

So I spent about an hour sanding the base with 200g sandpaper on a surface plate, and finishing with 600g emery paper, also on the surface plate. After that I could not pass a 0.003″ feeler gauge under the edges of the plate. Not dead flat, but should be close enough.

The surface plate, emery paper, and printing plate.

I had watched YouTube accounts of other AnyCubic Mono X owners using these magnetic plates, and finding that the extra thickness caused by the magnetic plate (2.6mm) was too great for the levelling mechanism to function. Various work arounds have been used, including moving the position sensor, and 3D printing a spacer for the sensor, to gain the extra 2.6mm.

My solution? With a milling machine waiting to be used?

The printing plate bracket.

I milled the screw slots 3mm longer, and milled 3mm deep rebates along the edges as shown above. Admittedly, the same result could have been achieved with drilling and filing.

The cost? $AUD40 for the new printer plate, and about the same for the magnetic surface.

Smith’s Screw -2. Square Threads.

When the Armstrong 80pr barrel was mounted on a wooden carriage, the angle of elevation was fixed by the weight of the breech resting on a wooden wedge shaped item called a quoin. The quoin was marked with graduations to correspond with degrees of elevation.

To change the elevation, the breech of the barrel was levered using the steps of the carriage cheeks as a fulcrum and the quoin position was adjusted. The trunnions of the barrel were placed forward of the centre of gravity, and the weight that gunners had to lever was considerable.

The angle of the wedge of the quoin was important. Too great and it could shoot out backwards when the gun was fired, and risk injury to the gunners. Too shallow would make it too long or restrict the range of elevations.

Fine adjustment of the angle of elevation was managed with a screw mechanism called a Smith’s Screw, introduced ~1860.

My CAD drawing. The bronze base is reasonably accurate. The other parts are based on the diagram below, or inferred.

I am currently making a Smith’s Screw for my 1:10 model. I must rely on old drawings of the Smith’s screw, because I have been unable to find a single example of a museum specimen anywhere. And the Smith’s Screws have been removed from all of the existing original wooden carriages. When not in use for actual firing, the screw and handle and gears were removed and placed in storage, along with the gun sights. Who knows what happened to the Smith’s screws when the guns became obsolete.

Some dimensions can be inferred from the base, which sometimes does remain in the original carriage, and from the rounded cavity in the iron pivoting slab which the screw supported. There are very few original wooden carriages, and I have been fortunate to find a handful in Victoria. I am told that they are exceptionally rare in UK, having been broken up when the guns became obsolete. Unfortunately, the drawings which I have found are of poor reproductive quality, and have no dimensions apart from the diameter of the screw (2.25″).

Smith’s Screw on the right.

One design feature of which I am reasonably certain is that the screw itself would have been a square thread. Acme threads were introduced in 1894, and replaced square threads in most applications because they were easier and cheaper to manufacture, stronger, and when the nut became worn it could be adjusted to take up the wear. Square thread nuts had to replaced when they became worn. The only downside to the Acme threads was that there was more lateral pressure on the nut, and greater friction and resistance to movement.

29º included angle is “Acme”, 30º is “trapezoidal”
Acme or square? Can be difficult to decide. Will it make any difference at 6mm diameter? It certainly makes a difference when making the thread.

So, I have been on a learning exercise to make a square thread. So far I have had about 6 failures. Maybe more. I can see why the square threads are more expensive than the Acme threads.

I had decided to make a 5mm diameter screw. A bit smaller than the 1:10 scale of the 2.25″/57mm original. Actually, 6mm would have been closer. (thinking). It needed to be 1.5″/38mm long. The pitch is unknown, but I had a tungsten cutter which appeared to have been ground for just such a purpose, with a width of 0.8mm, and therefore a pitch of 1.6mm. So the cutter determined the pitch. I have a CNC lathe, so I could decide on any pitch without changing gears. For example I could choose a pitch of 1.6mm, or 1.61mm. Whatever. But to be a square thread the thread depth should equal half of the pitch.

The next problem was with my CNC threading software. Mach 3 has a simple threading “wizard”, and I tried it on my CNC self converted Chinese lathe, which works fine for most applications, but the lathe’s shortcomings (lack of toolpost rigidity mainly), and use of stainless steel rod, gave poor results, then caused the cutter to snap.

So I switched to Ezilathe. Several problems due to my inexperience with square threads vs. conventional 60º threads and a software bug, prompted several calls to the software author, who resolved all software issues without much ado. (thanks Stuart)

But, I was still not getting good results, so I tried my Boxford CNC lathe. It is a beautiful little lathe, but with one serious fault. The tailstock is horrible to use. It is a real fiddle to install, limits the movements of the cross slide/toolpost, and worst of all I did not have a suitable morse 2 centre. I suppose that I should have taken time out and made a dead centre. But I didn’t. Wanting to see some results I pressed on.

With Ezilathe now working well, I decided to practice the square threading using 5mm brass rod. Without a tailstock the 40mm protrusion from the chuck was too much, and the rod bent. Sharpened the cutter, used minute depth of cut (0.02mm), and reduced the protrusion to 22mm, to make a 20mm long thread. Ahhhh. Looking better.

Now to try it with the steel.

That also worked well! A very nice square thread 20mm long, and the rod barely deflected at all. Copious lubricant being brushed on at every pass. 300 rpm. 0.02mm DOC. Sharp cutter.

Now, the rod duly square threaded is required for the screw, but 20mm was a bit short. It really needs to be a minimum of 30mm of thread. 38mm would have been ideal. And I need a length for the screw itself, and another length to make a tap to thread the nut. So I tried a 30mm protrusion. And heard a “click” as the cutter snapped. I think that the deflection causing chatter was the cause. Or maybe the discolouration of that end of the steel indicated that I had used it previously during silver soldering. Maybe I had hardened it.

So I stopped there to lick my wounds, went home and slept on the problem.

Next session I will: 1. make a dead centre for the Boxford, to support longer stick out. 2. Use silver steel instead of stainless steel. It will harden better for the tap, and might turn a bit easier. 3. Use 6mm rod instead of 5mm. For extra rigidity. 4. Make the thread 5mm longer than essential, to keep the cutter clear of the tailstock. I will turn the diameter of the extra 5mm length, down to 5mm diameter, to minimise the impact of the cutter plunge.

Oh, and by the way, I have been making left hand threads. The Boxford has a rear toolpost, and I forgot to invert the cutter which is required to reverse the direction of the chuck to make a right hand thread. I do not know what handedness the original thread had. But right hand is more common generally.

And if all that still fails I will make Acme threads. They will be easier, and at the scale I doubt that most observers will pick the difference.

Next day, next workshop session.

I decided that tailstock support was essential, so I went to my Colchester 2500 Master lathe, and plugged in the 2mm pitch settings. Easy. The tailstock was introduced. I made some right hand threads, on 6mm silver steel, no problems. Just time consuming. Had to regrind the 1mm width cutters several times, but eventually I had 2 reasonable lengths of square thread. One for the Smith’s Screw on the cannon, and one to make a tapping tool.

I machined a taper on the tapping tool, then used a Dremel with grinding wheel to produce the reliefs. Heated the tool to dull red heat and plunged it in cold water. Then gave it some slow heat to anneal it. It was still able to be filed, so the hardening process had not worked well. But it was to be used for only one tapped brass nut, so I accepted it, and proceeded.

The tap. It will the first and last square tap I will ever make. My eyesight was just not good enough to accurately grind the reliefs.

Cutting the thread in the brass nut was not easy. I needed several revisions of the thread cutter, using the Dremel with a small grinding wheel.

This is the brass nut on the square thread steel. Not as tight as I would have liked, but OK. Useable. 6mm diameter. 2mm pitch.
Fitting the nut to the base required some further relieving with the Dremel but there were still some tight spots, so I used a method from the past. Gumption.

Gumption is a kitchen cleanser which has a mild grinding action using rotten stone. It lasts only a few strokes, then disappears. But it worked brilliantly, and the nut now fits perfectly in the base. The excess Gumption just wipes or washes off.

So that was a day in the workshop. Not much to show. Maybe I should have spent the day with wine, women and song. It’s OK. SWMBO does not read these posts.

Next session to finish the threaded post with a hemispherical head. (just fantasising about the W, W, and S). Then the cog, handle and corresponding hole in the “iron” support.

Smith’s Screw -1

This is my CAD drawing of a Smith’s screw, which was used for fine adjustment of the barrel elevation of cannons on wooden carriage/platforms. The pivoting nut sits in the base. The threaded shaft is turned by the cog near the top which is turned with the iron lever which has protruding pins.

I started this mechanism for the Armstrong 80pr gun model today, by making the bronze base.

There were 4 components of the base, which were joined with silver solder. I could have printed the whole base and cast it in bronze, but I had nothing else to cast so decided to fabricate it with basic machining.

The 4 components. The bearing surface is bronze, the rest are of brass.
Squared up a lump of bronze, then used a ball nose cutter to make the rounded channel.
Carved out the desired bit…
And silver soldered the 4 components. Not very pretty at this point.
But with some filing and sanding it finished looking quite respectable.

Then to machine a recess in the posterior transom.

I did not want to make a mistake here, so did an air cut to test the CNC programming. First a shallow cylinder, then a deeper rectangular hole.
I spent an hour or so filing the part to make it fit into the recess. It was a neat fit, so pressed it into position.
A match to hold the “iron” quoin support in position for the photo.

Next session to make the cylindrical nut with a 5mm acme thread, and the matching threaded post.

I have made an appointment to see the original compressor unit at Warrnambool in a week, so I am deferring making that final component until I have checked some dimensions.

RML Cannon Sights, Trunnion Bearers

Ageing eyes require stronger glasses, longer arms, and acceptance of less than perfect results. However, this fault was not due to my deteriorating eyesight, but poor judgement.

I was drilling screw holes in the trunnion bearers. The bearers were tightly held by the dome head bolts so I drilled the brass and the wood together, with the carriage held in the milling vice. Unfortunately it was not held well enough, and shifted, causing the above.

So, what to do? Start again and make a new trunnion bearer? That would take maybe half a day. Or just fill it?

Filling it with copper coloured epoxy was quick and simple.
If anyone notices the filled hole I might remake the trunnion bearer one day.

In the photo above, note that I have made the gun sights.

Looks a bit rough at this magnification. 10BA locking screw. 2mm diameter shaft. I have never been able to see an actual original, but this pattern is based on an old diagram of a tangent sight of the period. The shaft would have been calibrated for distance.
The front sight. The sights were installed for firing, and removed for storage. In order that they are not lost from the model I have glued them in position. The machining marks are a bit ugly, but consistent with the actual finish on the full size barrels.
An interesting test. The trunnions bearers holding the weight of the barrel being held upside down.

Trunnion Bearings

The barrel trunnions sit in bronze bearings which are held in place with screws, and under the heads of the large carriage bolts shown above. Land based “garrison” guns, like the ones which I am currently modelling, often do not have trunnion caps, relying on the weight of the barrel and the slightly deeper bearings to keep the barrel in place during firing. Naval guns always had trunnion caps to avoid the “loose cannon” disaster on board warships.

The round pins under the flanges are actually rivets, placed with the intention of preventing splitting of the carriage wood in the trunnion region.

I had turned some bronze to size to fit the trunnions and the carriage cheek cut outs. Once before I had cut the entire trunnion bearing and its flanges from solid brass, but for this one I decided to cut the flanges from 1.6mm sheet, and silver solder them to the round section.

The first issue was how to cut off the unwanted top section.

I turned a mandrel from aluminium and pushed the bearing cylinders into place…

and marked the segment to be removed.

The cross definitely identifies the part to be removed.

and milled away the unwanted bits. The sacrificial aluminium mandrel prevents distortion from holding the thin cylinders in the milling vice.

checking that they will sit correctly….a rebate will be made in the carriage cheeks so the flanges sit flush with the cheek tops.

Then silver soldered the flanges using a mini oxy-propane torch. The soldering hearth is made of Hebel blocks, which are cut fairly flat and accurately. The back block is to prevent the light components from being blown out of position by the gas torch.

After some sanding on a flat surface, and a check of the parts on the trunnions to exclude distortion, all is looking good.

Next session I machined the rebates

Some shaping of the corners with a Dremel to fit the solder.
The finished result.

And I have added some more eye bolts…

But there was a problem with the eye bolts in the platform…Nuts on the inside of the slides prevented full movements of the carriage. On the originals, these nuts were buried, with nothing protruding. So I had to cut some pockets on the insides of the slides. I had not anticipated this problem when I bolted and glued the platform, and I really did not want to break it apart to make the pockets.

So, to cut these pockets in this very tight space, I made a special tool. Fortunately there was a corresponding hole on the other slide.

The finished pocket with the buried nut.
This cutter sits between the slides. After that, the 3mm driving rod is screwed into the base of the cutter through the other slide, and the pin at the cutting face is placed through the side to be cut. As you saw, it worked well. Mild steel, I did not bother hardening it, and it made the 4 cuts without any problems.
A bit rough but it did the job well.

So that is where this job has progressed to. Still to be made are the Smith’s elevating screw, the compressor, the sights, the quoin. And then the surface finish.

Cannon Recoil Control 1866

The 80 pr muzzle loading cannon was supplied to the colonial government of Victoria on a wooden traversing platform with a 5º slope.

I assumed that the slope was the means of absorbing the recoil.

The later iron platforms (from about 1875) had a 4º slope and hydraulic recoil control.

But, I was recently informed that there was a wooden “compressor”, which acted as a primitive brake, to reduce the distance of the barrel and carriage recoil. And that there was a compressor at the Flagstaff Hill Museum, Warrnambool, Victoria.

In fact I had previously seen the compressor, but neither I, nor I suspect the museum staff, really understood then how the compressor functioned.

Using Victorian Collections photographs published on the web, my own photographs, information from “The Artillerest” Peter Webster, some old drawings of wooden carriages and platforms, and a Google book “British Smooth Bore Artillery” by David McConnell, and a fair bit of deduction, I think that I have finally worked it out.

Firstly, the Victorian Collections photographs…

The compressor sits between the slides, with the rectangular iron tabs resting on top of the slides.
The elliptical central hole is filled with an iron elliptical post with a long handle attached to the top. When the handle is pulled backwards the cheeks are pushed outwards by 1/8″ 3.2mm, acting as a brake. The tapered iron bits had me stumped.
My drawing of the compressor with the brake applied. From above. When the handle is pushed forward, the gap between the cheeks closes and the brake is released. The pins push on the tapered outer iron cams to ensure closure of the cheeks. Ahhhh!
From below the compressor, with brake applied. The handle has a square drive in the square hole. A rope is tied in the distal handle hole.

Now to make one at 1:10 scale.

P.s. reader Jeff sent me some photos of a recoil control system used in 19th century USA, where a large metal screw clamp was utilised in these rifled muzzle loaders

Recoil Control

I had a phone conversation with Peter Webster, “The Artillerist”, yesterday, after I emailed him about the recoil control compressor which I had photographed at Flagstaff Hill, Warrnambool.

the very rare compressor. The loose metal bits on top are not part of the compressor.

I could not see how it could fit into the carriage or slide of the LowMoor cannon, or how it functioned.

Peter, who has a passion for Australian garrison artillery, 1788-1950, and has encyclopaedic knowledge on the subject, had seen this object at Warrnambool almost 20 years ago, realised what it was, and subsequently wrote a report for the museum. The compressor is classified as being extremely rare, most having been removed from the guns, probably to remove the gun metal components for scrap.

Peter explained to me that the flat, rectangular compressor sat between the platform slides with the metal corner tabs resting on top of the slides and the centre join of the compressor located along the centre line between the slides. The front and rear surfaces fitted between the cross members of the carriage.

The central hole was almost vertical. The hole is elliptical, not round. Sitting in the hole was a neat fitting elliptical post, which had a handle which protruded out to the right hand side between the carriage and the slide. When the handle was pulled, the post rotated and increased the separation of the 2 halves of the compressor, pushing them against the sides of the slides, as a brake.

Peter was sure that all carriage/platforms of this type would have been fitted with these compressors, until the wooden structures were replaced with the iron types a decade or so later.

So clearly I will have to make a scale model of the compressor for my current model.

This is a modified version of the carriage and traversing platform. It is the best drawing I could locate which shows the compressor insitu. Note also the central pivot and its large cross beam, which is bolted to the slides with the vertical bolts I had wondered about at Elsternwick. Peter told me that the Elsternwick guns would originally have been fitted with pivots, but removed due to being damaged during firing.

A Hot, Humid Day

Feeling a bit inactive on a hot humid day.

Thought that you might be interested in some more photos relating to RML’s.

That barrel could be an 80pr Armstrong, 3 meters long, which would make the lathe about 8 meters long. Note the date, the taper cutting mechanism, and the fact that they did some external turning with the trunnion ring insitu.
This is said to be the recoil controller from the wooden carriage/platform which is outside the Maritime Museum, Warrnambool. It is apparently an exceptionally rare item. Not on display. Shown to me because I asked questions about the cannon. I could not see how the recoil mechanism would have been fitted or functioned on the particular cannon. Picture of the Warrnambool cannon on its wooden carriage and platform follows. The loose metal objects on top are not related to the recoil mechanism.
The preserved, protected, and unrestored condition is very useful for modelling. LowMoor 68pr SML. 1861.
I have possibly shown this photo in a previous post. It is the 1866 80pr Armstrong RML on wooden carriage and platform at Fort Queenscliff, 30″ drive from my home. Missing the Smith Screw, sights and gunners side platforms, but otherwise in reasonably complete condition. No evidence of a rear gunners platform. Front left wheel bracket needs some attention.
and just to complete the photo collection of 80pr’s on wooden carriages and platforms, I revisited the Elsternwick cannons recently to get some more measurements. Early evening photo. Note the bolts hanging under the slides. They do not exist in any of the old drawings or photos. Maybe this one had a pivot support originally. Some of the very early platforms did have pivots, but they were removed as being unnecessary, and liable to damage when the gun was fired. Also note that none of these guns had trunnion caps, which were considered unnecessary in garrison guns. The trunnions do however sit slightly deeper than half way in the carriage cut outs.
For a bit of perspective I add this photo of manufacturing a 16″ barrel in WW2. USA factory.

Hot Weather. Smiths Elevating Screw.

We are having a La Nina summer. Relatively cool and wet. Humid. But, it is summer, and week long spells of over 30 degree centigrade days are expected, even in a “cool” summer. Today it will be 33c with high humidity, and those are not factors consistent with a pleasant workshop experience. So I will stay home and plan ahead how to make several components for the model Armstrong 80pr cannon on the wooden carriage and slide.

One item is the elevating mechanism for the 4 ton barrel. Several readers have helped with information about the mechanism, which I now believe to be a “Smith Elevating Screw” which adjusts the level of a heavy hinged iron bar, on which sits a wooden wedge called a “quoin”. The breech of the barrel sits on the quoin. The quoin is the coarse adjusting component, the screw is the fine adjusting mechanism.

This is the carriage and traversing platform which I am modelling at 1:10 scale. The barrel is an older smooth bore muzzle loader, but the dimensions of the carriage and platform seem identical to those of the 80pr Armstrongs at Elsternwick which I am modelling. The screw and quoin and iron bar are at the rear of the carriage.






Another 19th century drawing of the wooden carriage and platform, with a 110pr breech loading barrel. Also showing the Smith’s elevating screw.
This is the only picture which I could find with any detail of the Smith Elevating Screw.
….and this is a 1:9 miniature Smith Screw, made by Jefenry for his Armstrong 110pr breech loader, and whose videos I have shown in an older post. Those You Tube videos are really interesting to watch. Just do a search on “Jefenry”. These pictures are very useful to me. Thank you Jefenry!
And finally, a couple of recent photos of progress on the model to date. The Smith’s Screw fits into a half cylindrical nut which sits in a bronze enclosure within the rear transom.

The Strength of Silver Solder

I needed to add some substantially strong rings to the slide of the Armstrong 80pr on the wooden chassis. These rings are the attachment points of the blocks and tackle which are used to point the cannon in the direction of fire. i.e. the traversing mechanism.

Scaling off photographs and drawings I determined that the rings had an o.d. of 100mm, and an i.d. of 50mm. i.e the material was about 25mm diameter.

I had made some rings for a previous project, and had some of the material left over…

But, when I cut off the coils to make the rings I decided that they looked too spindly.

So I annealed some thicker rod which was 2.5mm brass…

… and wound it around a 5mm steel post….
….cut off the individual coils with heavy side cutters, and straightened them in the vice.
Then positioned them on an aerated concrete block to some 3mm all-thread….and silver soldered the rings to the all- thread. The lump of steel is just to keep the bits in position during soldering.
Drilled the slide beams after careful measuring, 3mm tapped as deep as possible, then completed the tapping through the 30mm beams with a long length of 3mm all-thread.
Screwed the eye bolts into position, and locked the other end with square nuts. Eventually the square nuts will be buried in the beams.
No where near finished, but looking more interesting with some bling bolted in place?

Armstrong Cannon Wooden Slide.. still more

and still not finished…..

Just to remind you that this is what I am modelling, at 1:10 scale. An 80pr Armstrong rifled muzzle loader, on a wooden carriage and slide. This pair is at Hopetoun Gardens, Elsternwick, Victoria.

I had imagined that this wooden chassis would be a relatively simple, quick build. The following photos show what I have accomplished in the last 3 days.

The gunner’s platform, supported by steel angle iron brackets, and the wooden “bollard” (I do not know what it is really called) which is used to wind a rope, and control descent of the cannon carriage down the slide to its firing position. And the odd metal bent rod bracket with the loop. I do not know what its function is. Does a reader know?
The underside. The gunner’s platform brackets were cut from some galvanised rectangular section tubing, then bent after heating with oxy-propane. Not perfect, but OK. The stainless steel bracket between the slides was cut from 1.5mm thick sheet and cold bent.

These little parts are very time consuming, but oddly satisfying to make.

And meanwhile, my friend Stuart has once again used his 30 watt fibre laser to engrave the barrel markings.

Top is Queen Victoria’s cypher, with the Order of the Garter motto. Then the site of the vent/touch hole (which will remain as a mark only), then the barrel proving marks, and then the weight of the barrel in hundred weights, quarter hundred weights, and pounds. (just over 4 tons). At bottom is a barrel centre mark. It lines up with another one on the muzzle.

On the left trunnion R.G.F. for Royal Gun Factory, the 24th barrel of this pattern made, and the year of manufacture. Some more polishing will improve the appearance and sharpness of the lettering.
On the right trunnion, the barrel centre line (horizontal), and trunnion centre line. Again barrel number 24.
And, this from reader Richard, who sent me this photo of an exquisite scale model studded projectile and trolley. Studs were prohibited from the Armstrong 80pr’s because they caused rapid wear of the bores.

Based I think on this original.

And a Bit More on the Armstrong Cannon Wooden Slide

Actually, the wooden slides were used on other British garrison cannons as well as Armstrongs. For example, at Flagstaff Hill, Warrnambool there is a 68pr LowMoor mounted on a wooden slide, which is identical to the slides used for the Elsternwick Armstrong 80pr’s. And I have a drawing of a breech loading 110pr which was also mounted on an almost identical slide. The only differences were in the carriages, and those differences were minor, depending on the diameter and weight of the various barrels.

So I have used measurements from several slides, located at Port Fairy, Warrnambool, and Elsternwick. The Warrnambool slide is unrestored and badly rotted in some places, allowing inspection of the interiors of the big longitudinal beams. The Elsternwick slides have been restored, painted, and have metal protective covers, which conceal details of the metal strips on the tops of the slides. The Port Fairy slides have been extensively and expertly restored.

And there are always compromises to be made when scaling down structures by a factor of 10. Fasteners for example are only approximately the scale dimensions.

Here are some pics of progress to date on the slide…

The metal strips are stainless steel. Not authentic but should polish nicely. 30 countersunk screws per side. I superglued the slides in position, then centre drilled, drilled and countersunk the holes. Getting the countersink depth was tricky and required a lot of trial and error on each hole. Then I filed any protruding bits of screws flush with the slide surface.

To shape the stainless steel strips, on Xmas Eve, I roughly bandsawed them to shape, then milled the edges to end up with 23mm wide strips, 480mm long. The steel is only 1mm thick, so holding it for milling required some planning. Guillotine or laser cutting would have been preferred, but not wanting to wait until mid January for a pro shop to cut it, I did it myself, using 2 bits of straight hardwood to hold the thin stock in 2 identical vices on the milling machine.

On one of the bits of hardwood I made a 23mm deep cut on a face of the wood, and rested the thin stainless steel on the lip thus formed. Then ran a sharp milling cutter along the surface of the wood, cutting the steel to size. That worked fairly well. As you can see, I removed about 10mm width of the steel in one run. Checked the dimensions, remounted the strip in the bits of wood, and finished the edge milling. Yes, I had to file the edges to remove the sharps.
Drilling the fastener holes, after supergluing the strips into position. The large hole is as in the originals, to allow access to the wheel bracket bolts.
The wheel brackets are finished, and bolted into position. Wherever possible I am using brass, bronze or stainless steel. A few more parts to be made and fitted, including carriage stops, a wooden bollard, gunners platform and tackle block rings. Then to decide about painting-finishing.
The wheel brackets are attached by a bolt which passes right through the longitudinal beams, to be secured with a round nut at the top.

More on the Armstrong Wooden Slide

Today I turned the chassis wheels, and the axles, washers, and pins.

First I tried to turn the wheels from some stainless steel shaft, but it was too hard, and destroyed HSS and carbide tips.

So, I changed to some free machining steel. A lot nicer.

A steel wheel, stainless steel axle, and brass end washers.
The washers have a curved face. I could have CNC’d the curve, but I used a method which had previously worked well. Using a milling bit, designed for milling a rounded edge. But works incredibly well when supported in the lathe toolpost.
Then parting the washers.
8 washers required. The lathe spindle had to be run in reverse. Quick, and excellent finish.

Then the axles were drilled for the retaining pin, and ground to length.

Next session in the workshop I will make the wheel bracket supporting bolts.

Making Wheel Brackets for a Model Armstrong Cannon using Subtraction.

For my previous model Armstrong 80pr cannons I made the iron carriage and slides using metal casting of 3D printed PLA filament for the complex castings. The results were OK, but I was not satisfied with the surface finish.

So, I bought a resin printer, and I have been very impressed with the results of the resin prints.

But, to date, I have been unable to get any castable wax resin suitable for the resin printer, with which to make the bronze castings.

So, I decided to revert to traditional machining methods, using reductive technology. Milling, lathe, etc, removing brass chips from bar stock to end up with useable parts.

This is what I am trying to make at 1:10 scale.

The wheel bracket appears to be made of cast iron. Possibly the wheel also, but it was probably turned in a lathe.
These are the brackets which I have milled and turned from 38mm brass bar stock. Not quite identical with the originals, but close enough I have decided.
Billets cut to length, with an allowance for holding in chuck. OAL 50mm.
The external shape was CNC’d.
The wheel slot was cut with a 3.5 mm thick slotting saw. 3 cuts to get the full 9.5mm width. The axle holes were spotted and drilled.

Then, I pondered long about how to remove the 20mm of stock which was allowed for the chuck jaws. I realised, too late, that I should have allowed another 10mm or so, because the parting line leaves too little to be held in the lathe chuck while parting.

So, I came up with this work holding solution…..

I drilled the hole in the bracket which will eventually house the mounting bolt on the model. 5mm diameter. Then drilled a 5mm hole in a piece of scrap, and bolted the 2 pieces together.

Actually, 5mm allthread is not much to hold a 36mm diameter piece for parting. So the thread was nutted and lock-nutted at each end. And torqued as tightly as I dared.

Holding the bolted extension in the 3 jaw, then slowly parted off the bracket. I stopped at 7mm, so the bolt holding the parts together did not crush the parts together and jam the parting tool.
Removed the bolt, and hacksawed the bracket from the bar. Then some belt sanding and finishing on a flat plate.

After parting the first part by hand winding the cross slide, I became more adventurous with the next three. Made sure that the gibs were tight, the carriage locked, and setting the spindle at 500rpm, used the power feed to do the parting automatically. With plenty of coolant-lubricant (my home made mixture of olive oil and kerosene.). But still finishing with a hacksaw.

With end result shown in photo 2. All good.

Next to make the wheels and axles from steel. Those brass bar offcuts will go into the “might be useful oneday” container.

Basic Grey Resin. Can it be used for casting?

So, I got a container of basic grey printer resin with my new Anycubic Mono X resin printer, and I have been learning the basics of resin printing. Lots to learn. Not like filament printing at all. Lots of failures, but getting there.

Almost at the point where I would like to make a metal casting, using the lost PLA/resin/wax method.

1 litre of basic grey resin costs about $AUD40.

On YouTube, the experts seem to be using special resins suitable for casting. For example Sirayatech Cast Resin. Costs about 3 times as much as the basic grey resin when postage from US, and taxes are added in. And about 6 times as much as filament on a weight basis.

But, I wondered, can basic grey resin be used for casting? It is MUCH cheaper.

So I performed a little experiment.

I placed two small PLA filament printed objects in the burn out oven, with a resin printed object of about the same size. And progressively turned up the temperatures.

On the left is a basic grey resin printed wheel bracket. Middle and right are filament printed PLA wheel and wheel bracket. All in the burnout oven. At 250ºc not much is happening. ( a quick door opening, photo, and door close.)
At 350ºc the resin object looks unchanged. The 2 PLA objects are melting.
Not a good photo, but at 430ºc the resin object is black, but retains its shape. The PLA objects have vapourised and disappeared.
This is the resin printed bracket after 15-20″ at 450ºc. It has left a shell of carbonised material. The PLA printed objects have disappeared. You can still see the bracket shape in the ash.
I let it cool down, and then crumbled it in my hand.

At the end of this simple test, I hesitate to title it an “experiment”, I have to conclude that basic grey printing resin is totally unsuitable for using as a “lost plastic” in metal casting. It leaves too much carbonised ash which would be incorporated into the melted bronze/aluminium.

OK. so I have ordered a litre of the expensive Sirayatech Cast resin.

Look What Santa Brought ME for Xmas!

Actually, I bought it myself. 71 years of experience has taught me that Santa has little clue what I really like. And although it was justified on the basis of being an Xmas present, it did not arrive until New Year’s Eve, thanks to Australia Post. It sat in a clearing facility for 10 days, about 5km from from my house. They were too busy to bring it the 5km. Maybe APO executives are still really pissed off at missing out on their Rolex watch bonuses this year, or whatever.

Anyway, it did finally arrive, and I enjoyed unboxing the bits, and reading the instructions.

IT is a resin printer. An Anycubic Mono X, which converts liquid into plastic objects, with an incredible degree of accuracy and surface detail. 0.05mm layers, which are invisible to my eyes.

On the left is a semi automatic alcohol washer, and an ultaviolet hardening light, which was strongly recommended by various users. After 2 days of use, I am SO glad that I paid the extra $$ for it.

So, why have I moved from a filament 3D printer, to a resin based printer? And paid over $AUD1000 for the gear? (if I had waited until after Xmas I would have got the gear for $100-150 less).

Well, the promise of greater surface detail, absence of visible printing lines, waiting hours rather than days for prints to finish for starters. And it is newer technology, which usually means better. But not always. And the fact that several johnsmachines.com readers have recommended the technology for my cannon parts was quite influential. (thanks guys! You were right.)

There are a few downsides, compared with filament printing.

The liquid resin does have a chemical odour, a bit like rotting fruit, but frankly, it is not too bad. Even SWMBO has not objected to my initial prints being conducted on our breakfast table.

And the resin is said to be toxic. Masks, gloves etc recommended. But I wear neither. I do wash my hands frequently, and I wipe any drops/spills quickly. If I start twitching or talking rubbish or scratching a rash, you will know why.

And the maximum print size is smaller than possible from my filament printer. That had a maximum print size of 300x300x400mm. The MonoX resin printer has a maximum print size of 200x125x245mm. That means that any larger models will need to be split into 2 or pieces, and the parts joined later. But the parts are so accurate, that joining them to make larger models is a real possibility. Bigger resin printers are available, but not at this entry level price.

Resin printing is a bit messy. And cleanliness is essential to get good results and to prevent damage to the machine components. So there are a lot of paper towels, tissues, and alcohol. And I mean 99% Isopropyl Alcohol. I bought 1 litre from Bunnings which cost $AUD29, only to discover that the cleaning machine requires 8 litres. I quickly discovered a firm which sells 20 litres for $AUD100 posted, and bought a container (at $5 per litre).

And what do I have to show you so far?

Well, this is the standard test print. It worked at the first attempt. It is quite small, and I used the default settings. Note: no visible printing lines, no lumps or bumps or support marks. Pretty good!

Then, I had a few frustrating failures. Parts which I had designed, refused to print properly. So I went online to the MonoX users group on Facebook, and I got immediate helpful advice, which did not appear in the official operators manual.

For example, my prints were so strongly attached to the build plate, that I had to destroy them to get them off.

The advice? 1. freeze the build plate and attached parts in the freezer for 30″, then heat them under hot water. They separated easily. 2. reduce the intensity and duration of the UV light to 80%, and 20 seconds (rather than the default 40 seconds). Problem solved.

Test prints, showing incredibly fine detail. And showing that 2 second burst of UV is optimal.
The level of detail is incredible. The fuzziness is my camera, not the print.

I am currently printing a cannon wheel bracket, as a test. With 1mm wall thickness. I am not interested in making plastic parts, except to use them to cast bronze or aluminium parts from them. The next test is to burn them in the potters oven to see how much ash remains.

Photo to be added…..

First actual part! 36mm diameter, 1mm thick walls. Drain holes added will be plugged with wax before burn out and casting. How perfect is that surface? (it is a wheel bracket for a wooden slide under an 80pr RML Armstrong cannon.)

Postscript for the failed bronze cannon pour

This is what the casting looked like after I had removed most of the investment, and turned a flat surface on the top of the casting.

I was surprised that the levering pins, and the big thread came out much better than the simpler flat surfaces. That might be because I had concentrated on those areas with the painted on investment slurry. And also because that end was at the bottom of the pour. That end got the first, most liquid melt, and the pressure of the melt above.

Turning the ragged end where the bronze was short.
It IS sort of interesting, no?

Having decided that my casting equipment is inadequate for this this size and weight object, I do not intend to have another attempt at making a 1:10 bronze Ottoman bombard. Plus, even this sad 3/4 complete component is VERY heavy. I would not enjoy carrying the full size 1:10 model.

The only question remains, what will I do with the above failure? It could join my gallery of failed parts (like the crankshaft of the triple expansion engine, which had a single incorrect dimension). It is useful to occasionally survey this gallery. It does motivate me to measure twice, cut once. Or it could become a very heavy and expensive door stop. Or I could drill out the bore and use it as a specimen flower vase. Or I could cut it up, and use the bronze in future projects. Maybe I will just sit on the decision for a while, unless any readers have any persuasive suggestions.

I am reminded of one of my late father’s aphorisms. “He (or she) who never made a mistake, has never made anything”.

Ottoman Bombard Model. Bronze Pour. Fail.

This project was put aside when I broke some ribs unloading the melting furnace which I had borrowed. Each of the 2 halves of the bombard weighed about 8 tonnes in the original, and in my model will weigh about 8 kg each.

These 8 kg parts will be the biggest which I have attempted to cast.

I am using the lost PLA method, having 3D printed the parts in PLA.

Today I attached the PLA breech to a PLA pouring funnel (also 3D printed), and poured the investment medium around the part in a 5″ steel cylinder.

First I repaired the PLA part, where it was a bit ragged. Poured some melted wax where there was a deficiency due to unsupported overhang during the 3D printing process. I deliberately overfilled the area with wax. The bronze in that area will require some turning to get the eventual correct thickness. Melted the wax with a soldering iron.
Glued the breech to the 3D printed funnel, also using melted wax. All of the PLA will melt and burn out during the “burnout” process in the potters oven. That is a lot of PLA to burn out, so the windows will be open.

In order to minimise the possibility of air bubbles sticking to surfaces and corners, I painted the entire model with investment, before positioning it in the casting cylinder, and filling it with investment slurry. It will set overnight, and I will commence the burnout in the morning.

Fingers crossed for the pour late tomorrow afternoon.

It is now the next evening. I am despondent.

I woke early, and when I arrived at the workshop at 7:30am turned on the potters oven, and placed the cylinder containing the PLA model and investment medium inside. (Problem #1.) The cylinder was too big to sit vertically or horizontally, so I placed it diagonally. It was awkward, and I was concerned that the bore piece, being supported only at one end, might break free. It did. (Problem #2.) Started the burnout cycle at 250ºc, slowly increasing to 750ºc over 8 hours.

While that was happening I set up the melting furnace, gas cylinders (3 of them), tongs, bucket of water, face masks, gloves, aluminised apron, etc outside. It was going to be a warm day. Unfortunately it was also windy. Not ideal.

The furnace (centre), gas cylinders rear, dry sand tray front. Bronze ingots weigh 12kg. I had predicted that the casting would weigh 10kg.

Stuart arrived, and he checked his furnace. We lit it to pre warm the furnace and crucible. (Problem #3.) The crucible fitted in the furnace, with little space to spare. Just enough for the crucible with its tongs to fit. Stuart commented that it looked very big. It was, I answered “a 14kg crucible”. When the 12kg of bronze eventually melted it only half filled the crucible. It was not the size which I had ordered. It was too big, and restricted the gas flame, reducing its effectiveness. The melting phase required 3 hours! Much too long. (Problem #4.) (PPS. note added 23 Dec. I checked the dimensions of the crucible. It is a 30kg crucible!!! No wonder it was too big for the furnace! I had ordered and paid for a 14kg crucible. No wonder it was too big for the furnace. I should have checked before using it.)

The crucible has to sit on the furnace floor, reducing the heat exchange surface area, and narrow space on the sides restricting the flame volume.

Then it appeared that the flame was not as fierce as Stuart expected. The gas was piped from 2 cylinders, and one was not icing up as expected. It was close to full. Why was the gas not coming through? Could there be a ball valve somewhere in the system? Later we discovered that the pipe from that cylinder worked in only one direction because there was indeed a hidden one way valve. There was no direction arrow. (Problem #5.)

So, when we did get to the pour, and discovered the central core broken free (#1),

I inverted the now red hot cylinder to shake the core free. I calculated that the bore would fill with bronze and need drilling later. But would there be enough molten bronze to fill the cavity? I had allowed 1.5-2kg extra bronze to cope with unexpected contingencies but this would be cutting things fine.

So, we did the pour. There was a LOT of slag, possibly due to the slow melt. The molten bronze seemed to pour OK, and it filled the mold and the central bore. But it stopped about 3 cm from the top. Bummer!. Not enough bronze. Oh well. A learning experience.

I have washed and scraped off most of the investment. Oh Dear. A total failure. But, the threads were OK, so not a total failure. The worst area was the middle section which I had not painted with investment slurry prior to the the investment pour. I think that the PLA must not have been water tight, leading to the moth eaten appearance.

And worst of all….

It is only half the weight of the cannon, and it is just too bloody heavy!

I could fix the mistakes, reprint the part, and recast it.

But, you know what? I am not going to. The biggest issue is that even if I am able to fix all of the problems, and get a good result, it will be too heavy to move around. It will be too heavy to use even as a door stop. Hmm. Maybe I will clean up the failure and use it as a heavy door stop. Either that, or cut it up and reuse the bronze in the next casting projects, which will be much smaller!

This will be another failed, abandoned project to add to the list. (Chess pieces, etc). Oh well. Live and learn.

(it does cause me to appreciate the Ottoman cannon makers of 1465 who cast these parts with wood fires, where each component weighed over 8 tonnes!)

In Search of an ELEVATING MECHANISM

“The Artillerist”, Peter Webster is a Sydney based expert on historic Australian artillery. So I contacted Peter to see if he could explain how the 4 ton barrel of the Armstrong 80pr was elevated when it was mounted on the wooden carriage and slide.

Peter explained in detail that there was a screw sitting in a gunmetal nut which raised an iron bar on which the breech of the barrel rested. If more depression of the barrel was required, a wooden wedge (quoin) was inserted between the barrel and the iron bar. Peter had seen this arrangement on a cannon at Fort Queenscliff.

Several other readers have sent me diagrams from old publications of the setup, and I sincerely thank those readers for their help. Here is one of the diagrams.

Even though the barrel is different from my Armstrong 80pr, the dimensions of the platform match precisely. And the elevating screw and the quoin show as dotted lines fairly clearly.

I could have made the model screw and quoin from these details, but I decided to visit the Queenscliff Fort to see them for myself. Queenscliff is only a 30″ drive away. It has been Covid closed to visitors for almost 2 years, but had reopened very recently. So off I went today.

The fort was built in the second half of the 19th century to guard Port Phillip Bay heads from the French, the Russians, and even the Americans(!). At that time Victoria was wealthy from the gold rush, and the authorities were worried about a raid to steal gold which was stored in Melbourne banks and the Treasury. The land walls of the fort were surrounded by a deep dry moat. The large black powder guns faced the sea.
The big guns were fired in anger only twice. First at the Pfalz, German steamer trying to escape Port Phillip Bay at the declaration of WW1. The “warning shot” almost hit the bow of the ship. Then there was a confrontation between the Australian pilot and the German captain. And the ship turned around, was commandeered, and was later used as a troop transport to take Australian soldiers to Gallipoli. The German crew were interned for the duration of the war. Astoundingly, the same gun was the first one to fire a shot in WW2, at least by Australians. But that was at an Australian ship which did not identify itself properly, so was a bit less glorious.

The 1.5 hr tour included the cells, the magazines, the remaining guns, the lighthouses, the museum.

Another interesting story which I had never previously heard, was from WW2, 1942. An aeroplane was launched from a Japanese submarine in Bass Strait. The plane flew around Port Phillip Bay, taking aerial reconnaisance photographs. It was spotted from Fort Queenscliff, but by the time it was realised to be the enemy, it had gone. Telephone calls to the Laverton airforce base were similarly unsuccessful in raising a response in time. The plane completed its mission and was picked up by the submarine. The pilot visited Australia after the war and related the story, and showed photographs. Needless to say, the Australian population was not informed until many years later. Google showed this article…https://www.ozatwar.com/japrecce/recce02.htm.

This lighthouse is still in use. Lighthouses are usually painted white, but this is one of only 3 black lighthouses in the world (?). Wonderfull stone masonry. Basalt.
The unusual “disappearing” gun. An Armstrong 8″ RBL. Manually loaded, it could fire 3 rounds per minute!
Similar mechanism, smaller gun.
The museum had many interesting pictures and exhibits. This one is the gunners loading a 10″ rifled muzzle loader. Taken in 1880.
Do you recognise the young lieutenant sitting right front? It is Australia’s most famous soldier. The son of German Jewish immigrants. He was the only soldier knighted by a British monarch on the battlefield, in 200 years. Later General Sir John Monash. He was in charge of the Queenscliff artillery in the 1890’s.
A famous rifle. Lee Enfield.
This had particular interest to me.

After the tour had finished I was quite disappointed not to have seen the gun and wooden carriage indicated by Peter Webster. So I asked the volunteer guide about it. She kindly introduced me to the gun expert at the museum. He took me to the only gun which matched the description, away from the tourist areas.

That’s me, next to the 80pr Armstrong rifled muzzle loader on a wooden carriage and slide.

Bummer! The elevating mechanism is missing, replaced by a wooden prop which was used when the gun was not in use.

Oh well. The tour was enjoyable.

Making a Scale Model Wooden Slide and Carriage for an Armstrong Cannon

Working with wood. It is quite nice to get back into the woodworking. And slightly daunting. Those saws can remove a finger or a limb in an instant of inattention. I use a 12″ radial arm saw, and an 18″ bandsaw. Somehow, the woodworking tools seem more dangerous than the mill or lathe. However, having seen videos and pictures of metal working lathe accidents, where an arm was ripped off at the shoulder, and similar, I know that they are ALL dangerous. At the time of writing I still have all of my bits.

At 1:10 scale, the wooden beams which form the base for the slides are 488mm long, and 30x30mm square section. They have a 5º slope back down to front.

I am using Victorian mountain ash, a pale, tight grained hardwood, and I happen to have some offcuts in my hoardings.

The wood is thicknessed to size, and the ends cut at 5º on the radial arm saw, which I bought about 45 years ago. Back then, B&D/DeWalt was considered a quality brand. I have previously decided which faces will be top and sides, depending on appearances.
checking cuts for squareness at the correct angle.
And today I used the CNC mill to cut out the carriage sides. 15mm mountain ash. The holes were drilled first, then brass pins hammered into the ash and the sacrificial base. Then the outside shape routed with a 6mm metalworking endmill. Some sharp internal corners will need to be filed or cut later.
I use a high speed spindle to do the routing at ~10,000 rpm.
Propping some bits together to get an idea of the size. The barrel is 3D printed plastic.

Oh. And some really useful woodworking tools which I bought from Banggood last year, and used for the first time on this project. They are laser cut spring steel, with holes and slots at 1mm and 0.25mm intervals, and a propelling pencil for marking. Accurate by woodworking standards, and they work really well, and were not overly expensive ($15-20 from memory).

And another bit of technology which I find useful with this project….

This is a plan of a 110pr Breech loader sitting on a wooden slide and carriage. I think that it is the one which was modelled by Jefenry which appeared in the video from my post of a day or two ago. On close inspection, it appears almost identical to the slide and carriage for my Armstrong 80pr. The width is different, due to the larger diameter of the breech loader barrel.

By fiddling with the magnification settings on our printer, I was able to print the plan on A3 paper, at a scale of 1:2 of my 1:10 model. The plan is quite accurate, allowing me to measure off dimensions of the components, angles and so on. This has been really useful.

Note that the wooden assembly is held together with large nutted bolts. And mortise/tenon joints as revealed by the Warrnambool LowMoor cannon. I will use bolts, and brass dowels, because MT joints are fiddly, difficult to make accurately, and will not be visible.

Armstrong RML Wooden Chassis – 3

This is the video which I shot at the Flagstaff Hill Maritime Museum of the LowMoor 68pr cannon on an original teak wooden slide and carriage. It focusses on structural aspects, which I can review when I am building the model. It will probably be boring for most viewers, but I am posting it in case it is useful or interesting to some.

The cannon is actually located outside the front entrance of the museum. On this occasion I did not go through the museum, but can highly recommend it for many fascinating exhibits, including the Armstrong 80pr RML cannons, artefacts from the tragic wreck of the “Loch Ard” especially the beautiful ceramic peacock, and the recreated colonial village. It is well worth visiting.

Armstrong RML Wooden Chassis – 2

When I sat down at the computer to draw up plans for the wooden chassis using the dimensions and photos I had obtained at Elsternwick, I realised that I needed some extra details. Some measurements I had just forgotten to take. And some details were not visible due to the protective covers on the Elsternwick cannons.

But, I remembered that there was a wooden chassis at the Maritime Museum, Warrnambool, and that it has not been restored. In fact it was an original teak slide and carriage, supporting an older smooth bore 68lb muzzle loader. I seemed to recall that the slides had rotted away to some extent, and that might reveal how the transverse beams were joined to the long slides, details that I had not been able to determine at Elsternwick. Being an older cannon, the slide and carriage might have been different from those at Elsternwick, but I decided to make the 2.5hr drive and check it out. 30 minutes further on were the restored wooden chasses at Port Fairy, so I decided to make a day of it.

The barrel is a 68pr Low Moor, smooth bore. The slide and carriage are unrestored teak, which is quite rare in the world. When I ran a tape measure over it, the dimensions were IDENTICAL to the Elsternwick cannons, despite the different barrels, which are 80pr Armstrong RML’s.

So I was able to obtain the missing measurements, and to see that the transverse beams were joined to the long slide beams with large mortise and tenon joints.

However I was still puzzled by the barrel elevation mechanism. Was it a quoin (wooden wedge), or a screw mechanism? Or possibly both? And if both, why?

The barrel support on one of the wooden carriages at Port Fairy. The black beam is iron, hinged at the front transom. Quite heavy. The triangular vertical prop is wood. This arrangement is almost identical to those at Elsternwick. This arrangement did not make sense to me.

But, when I checked my blog at home that night, several readers from Australia and USA/Canada had provided references which described the mechanism. Thanks Jefenry, David and Richard. (and Australian expert, “the Artillerist” Peter Webster).

This is a rifled breech loader of similar vintage, and probably identical slide and almost identical carriage design. Note the barrel elevating mechanism.

The barrel elevating mechanism is a large screw with the nut in the cross beam (the rear transom), which supports the hinged iron beam, and above that is a wooden wedge (quoin). Apparently the screw was for fine adjustments and the quoin for larger adjustments. I am reasonably convinced that was the arrangement of the Elsternwick 80pr Armstrong RML’s too.

In the diagram above note the roller/lever. That was used to lever up the rear of the carriage, to transfer the weight of the carriage and the barrel to the front wheels, permitting it to be rolled to the firing position at the front of the slide. Sometimes that process was bit uncontrolled, so the rope and bollard were added to control the rate of forward motion/descent.

Incidentally, that barrel is the one which was made in miniature by Jefenry, and featured on You Tube, firing at a range and off a canoe! Worth a search on You Tube. Just do a search on videos by Jefenry, or try these links.

The videos are from Jefenry, who is located in the USA.

Armstrong 80pr Cannon Wooden Chassis

So, today I battled 1.5 hours of post covid lockdown Melbourne traffic to take a closer look at the wooden slide and carriage of this 1866 Armstrong RML cannon which I am intending to model. There are 2 of them in the Hopetoun Gardens, Elsternwick. They are more complex than I had imagined.

The barrel is identical to the barrels which I had modelled on iron slides. The iron slides were a later improvement – modification.

It was a beautiful spring 20ºc day. I spent almost 3 hours photographing and measuring the wooden components. Some parts have been restored, and it was lucky that there are 2 examples to check and compare.

I was climbing over and under the cannon, and groundsman came over to check. Then a pair of grandparents came over with their 5 yo grand-daughter, and a further pleasant conversation followed.

Some examples of the photos…..

And an example of many pages of measurements and sketches…

There are 11 pages filled with details like this, representing my 3 hours.

And I still do not understand how the barrel elevation mechanism functioned. It could have been a wooden wedge called a quoin, but there appears to be a metallic disk set into the wooden bearer. Could there have been a screw mechanism which has since been removed/stolen/lost? Pictures on Google Images do not help. Does anyone know?

Armstrong 80pr RML – another one!

You might have seen the above photo in johnsmachines.com earlier this year. 2 Armstrong 80pr muzzle loading, rifled cannons are sitting on their ORIGINAL wooden slides, in Hopetoun Gardens, Elsternwick, Victoria. These were originally installed as garrison guns at Fort Gellibrand, Williamstown, Victoria and were never upgraded with the more modern, accurate iron and geared slides such as at Warrnambool, Port Fairy and Portland, and which were the inspiration for my 2020-21 modelling efforts.

I have decided that I will make another 1:10 scale model of the Armstrong 80pr RML, this time sitting on a wooden slide.

You might wonder why I am so obsessed with this particular cannon? Well, I wonder too. Perhaps it is the ready availability of an original in good condition, which I can visit, photograph and measure.

Anyway, I have made a start on this next model.

Cutting off 275mm of 76mm diameter bar. I bought this as mild steel, but it has remained so shiny in my damp workshop that I wonder if it is stainless.

The next step was to centre the 10kg rod in a 4 jaw chuck, install a 3 jaw steady, and drill the 16mm bore. Sorry, no photos, forgot. I had made a long series 16 mm drill bit by turning a shoulder on the shank of a good 16mm bit, and boring an accurate hole in the end of some 5/8″ (15.875mm) drill rod, and silver soldering them together. Then honing the bore to an accurate 16mm diameter, along its 275mm length. It worked well. So well, that I can insert a 16mm “projectile” in the bore, and watch it slowly drop through.

Then, continuing to hold the blank rod with its 16mm bore in the 4 jaw, and using the tailstock to hold the other end I manually turned the exterior of the barrel.

Why not CNC? Well, my CNC lathe is a bit light for turning a 10kg blank, and manual turning is still quite a pleasurable way to spend a couple of hours. The taper of the “chase” was done using the top slide set at 2.5º.

Turning the rounded chamfers. I could have CNC’d them, as I did for the original models, but in this instance I used a method which I had read about. That was to use a rounding over bit which is intended as a milling bit. But in this case it was held in the lathe tool post, and used as a form tool. It was very quick, and produced an excellent finish IMO.
Next step was to make the cascabel. This started as a 20mm x 1.5mm high tensile bolt. The wide part was a steel disk which I threaded, and glued to the bolt with Loctite 220. I turned the bolt head down to 20mm. Then CNC’d the shape above. Still to come is the rope bolt hole, and flattening the sides. Tapping the barrel to accept the cascabel occupied a couple of hours.
The new barrel has a better finish than my previous effort IMO. I used hydraulic oil mixed with kerosene as lubricant. 10kg stock originally, now weighs 4.2kg. Next step is the rifling.

Reconditioning a Tandem Trailer

My tandem trailer, was desperate for repairs and repainting. I bought the trailer about 23 years ago. It is 10′ x 5″, very solid construction, and a hydraulic tipper. I used it originally to transport animal manure to my olive trees. In recent years it gets more use on SWMBO’s building sites to remove builders rubbish.

The trailer as I bought it. I added the green “hungry sides” to increase the carrying capacity to about 5 cubic meters. The hydraulic pump runs off the Landcruiser battery. Here discharging rabbit manure to sit in piles for a few months before placing it around the olive trees.

Later, I increased the size of the ram to a multistage 5 ton unit, and changed the geometry to provide more lifting power. Also contracted a professional trailer maker to install Landcruiser hubs and wheels and heavier duty springs.

Landcruiser wheels. Looks more purposeful, and I can use the vehicle spare wheel as a trailer spare. On the farm I sometimes carried and tipped loads of 4-5 tons.

But the floor finally rusted through. So I installed a new 2mm thick steel floor over the top of the old rusted one. I should have removed the old rusted floor, but time was short, so I took the “lazy man’s” option.

Now, 23 years after the original trailer purchase, and about 18 years after the temporary floor fix, the floor needed to be replaced again. This time I did the job properly. I bought 2 sheets of checker-plate steel. Paid the supplier to fold the long edges. And started to remove both layers of the old floor.

The top layer of steel floor which I had welded in place came free after about 30 minutes of weld grinding. The original floor was attached by at least 100-200 welds, many in relatively inaccessible positions. After about 6 hours of exhausting work I removed about half of the badly rusted, excessively welded original floor. Another days work to remove the remainder. Then a lot of smoothing grinding, replaced one cross beam, treated rust, primed and painted the frame. Then attached the new checker plate. Then painted the entire trailer. The yellow seen is bright yellow before I added the red to give the hue an orange tint.
Some of the bends could only be made as the job progressed. This setup worked fairly well.
The folded up side lip should prevent water collecting along the corners, and slow down rusting in that rust prone location.
2 sheets of 2mm checker-plate, 2440mm x 1220mm. I had a 50mm lip folded along the long side of each sheet, cut one sheet into 3 pieces, tacked the pieces together. I asked my expert welder friend Tony to complete the welded joins. Here applying primer to the underside.

Then attached the new floor to the trailer frame with galvanised hex head screws. You might wonder why I did not weld it in place? Well, removing the previous floor which had been welded in position was job which I never want to repeat. Plus, whether the new floor is galvanised or painted, welding destroys the zinc or paint, including in areas which cannot be touched up. The technique which I used allowed all surfaces to be thoroughly painted. So I removed the newly joined floor, and primed and top coated all surfaces, including the frame underneath.

Then re-attached the new painted floor permanently to the frame with the gal screws, and cut off the protruding points. I decided to not weld the floor to the frame, because that would destroy the rust inhibiting paint. I used silicone roof and spout sealant in the screw holes, and between the trailer sides and the new floor side lips. Then applied more silicone sealant into any cracks between the side lips and trailer sides.

Oh, I forgot. The cross members were U sections with the opening at the top. No wonder they rusted. Any accumulated water could not escape. A really dumb design decision by the maker. So I drilled drain holes in every cross member, removed the rust with a needle gun, and painted the insides of the U sections. I will finish the painting when the steel repairs have been completed.

More painting required. The frame the hydraulic reservoir and pump, and trailer wheels yet to be prepared and top coated.
Quite a few hours of prep work, and 2 coats of paint to come. That is the 4 stage ram which I installed about 10 years ago. The new ram required a larger hydraulic oil reservoir, hence the extensions to the tank (bottom right). The end of this project is in sight!

Judging by the coats of existing paint, and alterations to the trailer construction, I reckon that this is the 4th major change to this trailer’s construction. It has done a lot of work. And lots more to come.

10 November 2021.

A bit more paint painting required in hidden areas, wheels, but this will be the final appearance. I am sure that the colour will not be to everyone’s taste, but I really like it. The spare wheel attaches to the post.
A new switch for the hydraulic tipper, and the lights still work. Ready for another decade or two.

It will probably outlast me.

Making a JCB 3CX Slew Lock Plate

I have a 35 year old JCB back hoe, a left over from when I grew olive trees and made olive oil. These days it is used only as a yard crane, and other small jobs on a 5 acre property. But since I am between model engine and cannon projects I decided to expend some TLC on the rather neglected JCB.

One feature which always made me grimace was the broken slew lock plate.

The slew lock plate supports the excavator boom and jib when the backhoe is driven between jobs. It takes the weight of the rear end, taking weight off the hydraulics. Unfortunately the old plate has been broken and re-welded so many times that it is IMO beyond repair.

A new plate is $AUD 1300 + GST I could not find a machine for wrecking, and was told that wrecked JCB 3CX’s are almost unknown, most owners, mostly farmers, keep them going for ever.

So I measured up the plate, drew it up on CAD, and had it laser cut from 20mm plate.

The laser cut bits. 20mm plate and 25mm plate hinges. Cost? $AUD 180

Deep V fillets were ground, and MIG welded.

Fitted to the excavator boom. I decided to not use the thin metal sloped flanges present on the original part, which I presume are to facilitate engaging the plate to the king post pin seen in the photo. I will engage the plate manually, by removing the securing pin (left) through the back hoe rear window.

JCB CX3 Backhoe Cylinder Seals

My JCB is a 1986 model, 35 years old. I have owned it for 10-12 years, using it for manure handling, as a yard crane, tree transplanting, and twice to lift a 50,000 litre water tank onto a tray truck. (in combination with a front end loader). Despite its age and hours of work (about 7200), it has been very reliable.

When I first bought it I engaged Enzed P/L to inspect and change any suspect hydraulic hoses, because many of them showed signs of cracking and delayering of the exteriors. And one had burst. I think that the onsite Enzed engineer remade and installed about 8-10 hoses.

Then recently, the hose to the rear bucket and boom controller burst. Well, actually it was the metal fitting which was crimped to the hose which split and allowed the hose to separate from the fitting, spilling quite a bit of hydraulic oil onto the ground. Enzed were on the job within a day, and an hour later the new large diameter hose and fittings were installed.

The hydraulic oil level was well down, and topped up with 20 litres.

I had been aware that one of the hydraulic cylinders had been leaking for many months, so not all of that 20 litre deficit was due to the burst hose. It had been leaking at the rate of one drop every 6 seconds for a long time, and increased to one drop per second recently.

I had recently purchased a kit of new seals for the leaking cylinder. After watching some YouTube videos, I decided to have a go at replacing the seals myself. No big deal really, except that I had not worked on a cylinder this large before.

This is the ram. The hydraulic hoses have been disconnected and covered with a clean rag to minimise any dirt entry. And the large heavy pins at each end have been removed.

The large gland nut was loosened before I removed the end pins. I had been warned that the nut would be extremely tight, and that it would be easier to loosen the nut while still attached to the JCB. The only spanner/wrench large enough was a Stillson wrench. I did not enjoy using it because it bit into the nut and marred the smooth surface. I had priced a new open ender spanner, but the cost was high so I used the Stillson. The Stillson was about a meter long, and the nut would not budge, despite using all of my strength and weight. Using a 1.5 meter pipe extension, the nut finally moved, and I loosened it until it stopped fighting. I caught much of the hydraulic oil which spilled out in a bucket, not to be reused of course.

I carried the ram into my workshop. At that moment I decided that any future resealing jobs on larger rams would be done professionally. It was quite heavy.

In the workshop I completed the removal of the large gland nut, discovered that the gland O ring and the main seal were in pieces.

Then removed the piston and its rod from the cylinder by pulling carefully.

The piston seals looked OK to my inexpert eye. But I had purchased a whole new kit of seals, including the piston seals and guides, so I replaced them all.

The new piston seals above, and the new gland seals inside and out, bottom. The gland and piston, and my hands were cleaned thoroughly, multiple times before and during the procedure. Most of them went on without much difficulty. The big rubber seal on the outside of the piston was the hardest. For that I used a heavy cable tie looped through the seal, to pull it into position. All good so far.

By the way, I had obtained a JCB service manual for my machine online, from Best Manuals, (USA) for $US19.99 and downloaded electronically. It had some very useful information. Including that replacement seals might be different from the originals. And they were. They looked different.

The seals went onto the piston fairly easily, with the assistance of a large cable tie, which was used to pull the large central rubber seal into its groove. The remainder of the piston seals were split, and positioned easily. The gland seals fitted easily, except for the large internal rubber seal which required considerable pushing and effort.

The gland was then pushed onto the piston rod, then the piston was screwed on, after cleaning the threads, treating them with Loctite 7471, and thread retainer 720. Then tightened with wrench and 1.5m extension.

My very untidy workshop, undoing the piston nut. The same setup for tightening. The manual specified 300 ft-lb, but my torque wrench does not measure such a large tension, so I just used all of my strength to tighten the nut, using the extension. The aluminium jaws are just supporting the rod. Most of the pressure is held by the foreground vice.

Then I attempted to insert the piston into the cylinder. But it would not go. So I pushed harder. Still no go. Tried wiggling. twisting, pushing harder. No Go. Bummer. 4pm on a Friday afternoon. Long holiday weekend imminent. Threw the parts into the boot and drove to Enzed. About 15″ away. Maybe there is a special tool or press to push the parts together?

They helped me immediately. I guess that my previous business a few days earlier and quick payment of their bill helped. They mounted the cylinder in a chain- pipe vice, and pushed and strained, but no better result than I had. The piston with its new seals just would not fit into the cylinder.

So, he compared the old and the new seals. The new ones were 0.3mm thicker than the old ones. And the diameters seemed larger. I had bought the seals from a JCB dealer, who had said that they were “after market”. Originals no longer made for such an old machine.

Discussion. Decision. Use the old piston seals. The new gland seals seemed fine, so keep them. The old piston seals appeared to be in good condition, and they were installed. And guess what? The piston slid into the cylinder with some pushing. The gland nut was tightened. (with a Stillson I noted).

The charge for 30 minutes of heavy, dirty, specialist time??? $AUD 23.00. I said, “that seems too cheap”. “That’s OK” he said. They will continue to get my business.

Today I re-installed the ram on the JCB.

Fired up the diesel. No leaks!

Operated the bucket control……no leaks, but no movement! Bummer! What now.

Hmm. Could I have put the hoses on back to front? No. They looked correct.

But hang on, the cylinder is facing the wrong way! The paint scuff marks which were on the outside are now facing inside!

I HAD INSTALLED THE RAM 180º ROTATED!

So, left the ram as was, switched the hoses, and tried again.

WOO HOO! No Leaks! (including when I tried different ram positions off camera).

JCB 3CX 4×4. Next project?

I am still waiting to pour bronze to make a 1:10 scale Ottoman bombard. I have all the equipment and materials ready to go. But, held up by 1. needing some dry, wind free days, 2. ability to have a friend on hand to assist with the pour. I need 2 successive days for making each mould and doing the pour. Waiting, waiting. Meanwhile, SWMBO has had me breaking up a concrete drive, manually loading the broken up concrete, and transporting it to the recycler. It took 3 x 2 ton loads, so far, and still more to go.

Then in lockdown, we decided to fix a leaking balcony at home, and replace some rotting, ceiling boards under the leaks. At 71, I dislike working on ladders, above my head. Almost finished, thank goodness. And no more broken bones.

The leaks have been fixed. And the 8×2 beams are intact.
Fortunately I was able to buy some boards to match the old ones. Doesn’t look much, but those patches took 4 sessions of about 4 hours each. Even more fortunately, SWMBO does not trust my painting skills, so she will do the painting after I have fitted the corner mouldings.

The lockdown restrictions eased a bit last weekend, permitting me to visit my workshop. I have been waiting for some suitable weather to burn some rubbish, and it was not too windy a couple of days ago, so this was the first task…

First weeks of spring, and with a fire permit obtained from the local authority, I had some fun with this. But even so, I had to put out some spot fires in the surrounding grass, which has already started to dry off. I am glad that I did not wait another week or two.

I have been considering my next modelling project. Nothing really is grabbing my attention. But I had to use the JCB backhoe to load the concrete onto the tipping trailer and I was aware that the JCB is looking really tired. Not surprising, considering that it is 36 years old, and has 7200 hours on the clock. I bought it third hand, more than a decade ago, and used it for general farm jobs, including manure handling, transplanting mature olive trees, as a yard crane, moving machinery, digging trenches. As a general farm machine it was incredibly useful. When the farm was sold, it was just about the only big machine which I retained, because even on 5 acres it is still used occasionally.

Transplanting a 10 year old olive tree. Even with many cut roots, they transplant very successfully.
Handy for heavy lifting. My tractor at back was not getting any use so it is on permanent loan to a neighbour.
4 way bucket at the front, can lift 1.5 tons. One of the rams has developed a leak, and will need resealing. The Perkins diesel starts easily and runs well.
The back end is slightly loose, but not bad for its age. The tyres are down to about 15-20%. As you can see the paint work is ready for renewal, but there is no serious rust. The white roof is worst, so that is the first item for repainting. The rams are all good.
I made this grab attachment for picking up vegetation trash, heavy beams etc.
…like this heavy RSJ…
I do not know what this plate is called. It secures the boom during travelling. It has been welded/repaired more than once, but as you can see the left hand yoke is broken and non functional. It is a casting. I have been searching for another one from a wrecked JCB, but no luck so far. So I am drawing up plans for fabricating one from 20mm steel plate. Some more laser cutting and mig welding required. (ps. it is called a “slew lock”).
The interior of the cabin is not too bad. All of the controls function. The rapid steering knob was missing, so today I fitted this gear stick knob from my “might be useful one day” collection. It has a large spider embedded in the clear plastic.

So, until some new model engineering project takes control of my life, I will spend some time and TLC on the JCB.

An Engineer’s View of Ancient Egypt. (Book Review)

I watch YouTube videos about megalithic sites around the world, including Peru, Cambodia, Russia, Bolivia, and especially, Egypt. I have been fascinated in the subject for over 50 years, since reading an article in National Geographic as a teenager, about the almost unbelievable stone work in Peru which was then ascribed to the Incas, (but that Inca origin theory now has many serious doubters).

One of those YT sites, “UnchartedX” , (to which I subscribe and support), frequently refers to the book “Lost Technologies of Ancient Egypt”, and recently did a 2 hour interview with the author, Christopher Dunn. The book was published in 2010, based on many visits to Egypt by the author. The interview led me to purchasing and reading the book. Although now 9 years (oops 11 years) since publication, his work is respected by Egyptologists, academics, and more free thinking enthusiasts such as YouTubers like Ben of UnchartedX, quite an accomplishment considering the degree of hostility between the opposing views.

Christopher Dunn is/was a toolmaker, engineer, and manager in the US aerospace industry, and expert user of CAD, CAM, lasers, metrology, and photogrammetry. He is also into ancient history. So when he visited Egypt he looked at the pyramids and other buildings and monuments, with the eyes of an engineer, and wondered how they “did it”. Over the course of many visits, he took increasingly sophisticated metrology devices and started to measure and take detailed photographs of monuments, temples, statues and quarries. He was staggered to discover the degree of precision to which many of these huge objects were made, in many cases of granite or basalt some of the hardest of all stones.

And he examined magnified views of the surfaces, to see the marks which remained, which might give clues about the tools which were used to create the objects, which in some cases are at least 4500 years old.

He carefully analyses the Egyptologists’ views that the tools were simple and primitive. Like copper chisels, and stone pounding rocks, and while not dismissing those views out of hand, leaves us with the impression that such results would be almost impossible in this CAD CAM era, and much less with copper tools and stone pounders. He does not mention aliens or pre-dynastic civilisations, but just states that the tools which made the pyramids, obelisks, huge precise statues, and stone boxes, those tools, unlike the copper chisels and stone pounders, have never been found.

He does point out evidence of large circular saws with a 38 feet diameter blade, hole saws up to 6″ diameter, and straight saws which have left tell tale marks in stone objects and quarries in many places.

In many cases, such as the huge, incredibly precise stone boxes in the Serapeum, and the absolutely identical pair of 40′ statues of Rameses 2, he just states “we have no idea how this was done”. The precision is not just in linear measurements, but in complex curves, and surface shapes and areas.

Dunn’s analysis is principally about the tools and engineering of Ancient Egypt. Equally fascinating, but not covered in this book, are the mathematics associated with the pyramids, but that is another story. Also, he does not believe that the Great Pyramid was designed as a tomb, but as a machine. But that also is the subject of another of his books, which I have not, as yet, read.

“Lost Technologies” is 360 pages, paper bound, illustrated with many black and white photos of variable quality, many excellent diagrams, and 16 pages of good colour plates.

The text is technical, but quite readable cover to cover. I found it difficult to put down. If you enjoyed Simon Winchester’s “Exactly” you will probably like this one.

Cost about $AUD30 from Amazon Books.

Can’t wait to visit Egypt.

3D Printer Upgrades. Are They Worth It?

This is not an in-depth examination of the question. It is rather my experience with a particular 3D printer. But I believe that my experience has been experienced by many other 3D printer owners, so I have decided to make this record.

The printer which I purchased was a Creality CR 10s. I bought it in January 2020. I had been considering such a purchase for a year or more, and finally took the plunge when faced by making components for the model Armstrong cannon which featured in this blog over the past 18 months, I realised that I would have to metal cast quite a few complex parts. And the “lost PLA” method seemed like the best option to cast those parts.

So I accumulated the equipment for printing the PLA, making the molds from jeweller’s investment medium, a potter’s oven for burning out the PLA and baking the moulds, a furnace for melting the aluminium and bronze, and assorted other necessary paraphernalia.

Choosing the 3D printer was difficult, coming from a knowledge base of close to zero. I asked members of my model engineering society which printers they chose, and why. I watched numerous YouTube videos, and read reviews. As usual, I discovered that the more information you absorb, the more confusing it all becomes. I have the same feelings when researching which car or camera to buy. Eventually, I decided to buy a lowish cost printer, with the idea that I would eventually replace it with a better unit for long term use.

For this first 3D printer I wanted a well known brand with a good reputation, a build volume which would allow me to print the biggest component of the model cannon (the barrel, which is 300mm long x 65mm x 100mm).

I was still mulling this choice when Amazon advertised a special deal for the CR10s, and I made a snap decision to take the plunge. Would I make the same choice today? Quite possibly (actually, no. see below). Although technology has advanced. I am now considering whether to add an Elegoo Saturn resin 3D printer to my ever growing list of machines.

So this is what I bought. It is an open frame 3D printer, with a separate box for the motherboard and controls, and a side mounted spool. Single extruder. Advertised as an auto self levelling base (but it is not. It is manual, time consuming and fiddly). Filament end detection (hence the “s” after the 10), which works well. The build volume is 300x300x400(h), which is at the high end of low cost 3D printers, and bigger than any of the low/medium cost resin printers. I used close to the full extents of the volume on several occasions.

Creality CR10s. Here printing in PLA, a gear which will be used to test the dimensions for the cannon barrel elevation gears. This was one of the first items which I printed. I was satisfied with the print quality. The arms which triangulate the vertical tracks on the printer were the first modification of the printer which I made. My decision to add the triangulation arms was based on my gut feeling that they would improve the printer. They cost $AUD65. Creality now includes them as standard equipment, which justifies my decision IMO. The cables between the stepper motors and the control box are messy and a nuisance and I watch them every time I do a print. I would NOT buy this printer again, mainly because of the cable arrangement.

Actually, the very first modification was the slicer software. The printer came with a free version of “Cura”, but I accepted some expert advice to use “Simplify 3D”, which I purchased ($AUD 175) and used exclusively until recently. More about that later.

The instructions for using the printer were in an illustrated 10 page booklet, and a pdf file. As instructions for assembling the printer, they were just OK (do manufacturers EVER test their instruction booklets on novices??). As instructions for fault diagnosis they are hopelessly inadequate. In my previous post I showed a paper back book which would have been immensely useful when I started this 3D printing journey, and HAS been immensely useful after almost 2 years of wallowing about in ignorance. (“3D Printing Failures” by Sean Aranda).

By trial and error (mostly error), I printed the parts for my model cannon, and also came to grips with the casting processes.

BUT. When I started printing components for my next project I experienced failures and frustrations which I could not overcome. The Ottoman bombard has only 2 components, the breech and the barrel, which I intend to cast in bronze, using the lost PLA technique. These will be the biggest castings, and biggest 3D prints which I have attempted. Not surprisingly, I had problems with the 3D prints. Some of my attempts at fixing the problems caused further problems. After reading Sean Aranda’s book, discovered that my problems had ALL been described, catalogued, and fixes known.

The problems were:

1. Poor plate adhesion causing models to break free during printing.

2. Poor adhesion between layers causing gaps and structural failures.

3. XY shifting between layers

3. Gaps between filaments which would cause casting holes.

4. Excessive stringing.

5. Lumps on surfaces.

And this was typical of the failures….

The barrel on the left shows layer shifting on the pins. The failures on the right show stringing, surface lumps, and adhesion failures between layers and within layers. A complete barrel print takes over 4 days, so there is a lot of printing time in that bin.

Then I decided on some upgrades….

  1. An enclosure to prevents drafts, and keep the printing environment warm during cold nights. $AUD155. A temperature and humidity logger kept a record of overnight temperatures. The heated printer bed provided the heat. I noted that temperatures remained between 22 and 26ºc inside the enclosure.
  2. An all-metal fully geared extruder. $AUD25
  3. A filament dehydrator, and warmer. “Sunlu” brand. $AUD60. Old filament can be reconditioned by warming at 50ºc for 4-8 hours. The same machine can hold the filament during printing to keep it warm and dry.

Around this time I experienced a serious filament leak and blockage which bent the hot end enclosure, broke the wire to the thermostat, and broke some insulating material. The leak was caused by a loose extruder nozzle, and an imperfectly seated Bowden tube. It was probably repairable, but when I saw that the cost of a replacement unit, including the wiring loom, hot end, 2 fans, silicon boot, etc was only $AUD35. So I bought one, had it installed easily in a few minutes. It came very well packaged, and quickly.

Also about this time I read Sean Aranda’s book. It has been a game changer.

Aranda uses “Cura”, and although his fixes can been used by any other slicer, one of my problems was holes between walls and internal surfaces. He says that this is a problem which is worse with “Simplify 3D” than with “Cura”, and he also thinks that “Cura is a better program overall, mainly due to the quality and number of online updates. The fact that “Cura” is free is an added bonus.

4. Sean Aranda’s book. “3D Printing Failures”

5. Changed slicer to “Cura”. Although it is called “Ultimater Cura” it works on most if not all 3D filament printers.

6. Changed the stick-on printing surface to a new 3M cover. This was after I read the product information which stated that these surfaces last for only 10 prints! I am quite sure that mine lasted for at least 50 prints before becoming unusable. Now I print on different areas of the surface, and keep a record of the number of prints at each location. Since then I have bought a magnetic cover which I will use when the current 3M cover starts to fail. (p.s. I have now installed the magnetic base, and so far, it has been wonderful!). No break aways despite not using brims or platforms, and easy to remove prints

After all of those changes my prints have been excellent. No break aways, no X-Y layer shifts, good adhesion between layers, better surfaces, and no holes/gaps between filaments. The only problem is that I am not sure exactly which changes were effective and which ones were not. Probably they have all helped to a degree.

Postscript. I have been considering buying an Elegoo Saturn resin printer, or maybe even substituting the Saturn for my Creality CR-10s. From the reviews the Saturn produces much smoother surfaces, and more precise dimensions. And the prints are much faster. My 3 and 4 day barrel prints could be printed 5-10 times faster. The known down side is the is the cost of the machine (on special at Amazon at present for $AUD639), the smell, the need to avoid skin contact with the uncured resin, the desirability of a print washer/UV curer, and the need for extra space. The other major consideration for me is the smaller maximum print size. 200x192x125mm. The bombard parts would need to printed in halves and glued together in order to make the molds. So, while the CR 10s is working well, I will hold off buying the resin printer. There is some advantage in waiting because 3D printing is a constantly evolving and improving technology.

The most recent print. The breech of the Ottoman bombard, in bronze coloured PLA. Almost a perfect print. Sliced with Cura. I did not specify any supports, despite some horizontal overhanging surfaces, and that resulted in some loose threads on one surface (RHS), which should clean up reasonably. After that cleanup I will probably do some build up of the surface in wax. The print is 240mm long, 107mm diameter, and took 50 hours. I will be satisfied if the bronze casting looks as good as the print. A pity that the print will disappear during PLA burnout.
And this one is a tool to try different clearance settings between close fitting parts. 0.5mm down to 0.15mm. Downloaded from “Makers Muse” website. Printed all components together. After minimal efforts to free up the parts, all clearances functioned, so if I was to print some gears, or other working model, I would allow only 0.15mm clearance at the design stage. I am not bothered by the substandard finish. I had set the extrusion width ratio at 0.9, and allowed no overlap for the walls and infill, so some infill gaps were present.

So, were the upgraded components worth it? A resounding yes, as far as I am concerned. Still pondering the Elegoo Saturn

P.S. a month or 2 later. Since I wrote the original article I have taken delivery of, and installed some 1 meter cable extensions, which were made for this machine. Obviously I am not the only Cr10s owner to have decided that the cables are a bit too short. The 6 or 7 cables were fitted with connectors and installed quickly and easily. The printer functions perfectly, and I can now place the control box a comfortable distance from the printer enclosure without worrying whether the too short cables will cause a print failure. Actually, the one meter extensions are a bit too long, and need to be carefully positioned to avoid snagging. Half a meter extensions would have been ideal. And the cost? $AUD35 with free postage. Considering the labour involved in making and packaging these items, the price was cheap.

2 Man Tongs

I guess that title should read “2 Person Tongs” but I doubt that SWMBO will be volunteering.

I am still planning to pour a model bronze Ottoman bombard.

Wooden version. 520mm long, 107 diameter. I visited the 5.2 meter original near Portsmouth UK after I made this model, and I have refined the design of the new model.

The plastic model has been 3D printed, the flasks for the investment powder mould are ready, and I have the potter’s oven ready to dry, burnout, bake, and heat the moulds.

I have borrowed a melting furnace from Stuart Tankard, which is large enough to fit the crucible.  The crucible has 14kg capacity.  The crucible itself weighs 4kg.  Unloading the furnace from my Toyota Landcruiser cost me a couple of broken ribs, which set back the project a few weeks. 

Then I wondered about tongs to insert the crucible into the furnace, and, more importantly, how to lift the crucible full of molten bronze out of the furnace and pour the bronze into the moulds.  The weight to lift and pour I estimate to be: bronze 10kg, crucible 4kg, plus tongs say 4kg = 18kg.   The crucible with its bronze load will be at approx. 1100ºc / 2000ºf so some distance will be required for the gloved hands from the red-hot load.

3kg graphite crucible with tongs on the left, then ~5kg, and 2 x ~6kg. My new 14kg crucible at rear.

I have several pairs of tongs for smaller crucibles, but nothing approaching a 14kg crucible.  So I asked Stuart T for his thoughts on the matter.  He recalled seeing a video by an MSMEE member and suggested that I check it out.

John M’s tongs looked like they had been designed by an engineer, which was actually the case.  I contacted him (by email because Melbourne is in Covid lockdown), and he generously offered to send photos, a video and a drawing.

I copied his design, with a few modifications based on the materials which I had on hand, and also to enable a 2 man lift and pour.  In retrospect, I could have fabricated a one man pouring apparatus, using a swivel on a frame, but to be honest I would prefer someone else present for safety reasons. 

8″/204mm ID pipe. I need to reduce the ID to 185mm
To reduce the diameter from 204 to 185mm diameter I cut out 19 x 3.2 = 60mm plus a bit extra, then rolled the new diameter to 185mm ID. (shop made rolling machine)
Yep, it fits the crucible.

The remainder of the tongs construction was basic cutting, welding, and drilling.

I cut more of the tongs away to reduce the opening diameter, to still fit Stuart’s furnace. The overshot bent handle closure requires a positive action to open the tongs- a safety feature.
With the second man handle slotted in place
Testing the crucible and tongs in Staurt’s furnace. Cold.
The open position

I used to be a half reasonable amateur welder, but lack of ongoing practice lately, and dodgy eyesight is my excuse for the lumpy welds and essential use of an angle grinder.

Next steps….   I need some dry, non windy weather, and availability of assistance for the pour.  I will make the first mould, of the breech since it is shorter than the barrel, dry it, burn out the PLA, and bake it at 750ºc.  That will take most of a day.  While the baking is in progress (about 4 hours), I will start the melting of the bronze ingot.  Stuart says that I will require 2 full 20kg cylinders of propane.

Then the pour.  Then after some cooling with fingers crossed. Camera running…..

RETAIL THERAPY for LOCKDOWN

The 6th Victorian Covid lockdown was the shortest, but seemed to hit me the hardest. It was unexpectedly relaxed after only 5 days in regional Victoria, where I live. With escalating numbers in Melbourne, and Sydney, and NSW reacting by putting its collective heads in the sand we expected the be in lockdown for weeks or months, and frankly it was quite depressing. For the first 3-4 days I did a bit of garden tidying (with a chainsaw, much to SWMBO’s horror), and time on YouTube, Ebay, Banggood and Amazon. A fair bit of impulse buying, as follows.

Paragraph deleted. My political and religious views have predictably caused offense to some of my readers. While I do not resile from any of those views I accept that others have different views, and me having a rant is unlikely to be at all persuasive. So I have removed the paragraph. For those who agree with my views, my apology. Any further conversation about Trump, Liberal and labor politics in Oz, and religion, will have to be in private. (I still consider Trump to be a lying, ignorant, con man, and a disaster for USA and western democracies.)

So, having offended and lost 3/4 of my readers I will get back to my little buying spree…..

Firstly, a book.

I read some good reviews about this book, and since I have had considerable frustration with my 3D printing of late, I decided to buy it. 3D PRINTING FAILURES by SEAN ARANDA.

Paper back, 298 pages, large format, large print font size, 2020 edition. Under $AUD30 including postage from Amazon.Australia.

And it looks excellent. Clearly laid out and written, lots of pictures and diagrams, and the author even gives his email address and offers expert help if there should be a problem not covered in the book.

Some of the pictures admittedly are not great quality, but the author has a service which astounded me. If proof of purchase is emailed to him he will send high definition colour photographs for download. He sent me all of the photographs within 24 hours of my request. AND, a pdf version of the entire book. AND, a promise to send me free of charge a PDF version of the 2022 edition which will be published near the end of this year!

I have cherry picked some of the chapters and I am VERY impressed. They are VERY helpful. Some random pages follow….

This book should be included with every 3D filament printer purchased. Note that it does not cover liquid 3D printers.

In my previous post I showed a photograph of the enclosure which I cobbled together from cartons and a blanket to try and avoid printing problems arising from overnight temperature drops, and draughts. I intended to make an enclosure from MDF and perspex, but while browsing Ebay came across this one.

As you can see it was not a trivial cost. But when I factored in the difficulty in obtaining the materials during the lockdown, and the fact that the commercial one claimed some fire resistance, I bought it.

It came today, and with some levering of the cover on the frame, it assembled quite neatly, tightly, and well. Here it is with my printer.

As you can see the electronic control box is outside the enclosure. There is a flap on top for those who prefer the filament reel on top.

The front and top zip open. And there is some spare room for bits and pieces. It does look slightly neater than the previously used cardboard boxes. The printer is fully enclosed, even with a build in floor. The price seems to have risen a bit since I paid for this one. Time will tell if the print quality improves. I am predicting that the print quality will improve. After reading the chapter on fire safety and 3D printing in the book above I will feel more comfortable about leaving the printer unattended with this “Fire proof” enclosure. I suggest interpret that as “fire resistant”. I will be watching temperatures closely for the first few runs.

Still on the subject of retail therapy, a couple more purchases….

This is a woodworker’s gauge from Banggood. I bought it after watching a YouTube video about its uses. Nicely made, and reasonably accurate by wood working standards. I will do a separate post about it when I have more fully explored its applications. (it is for making perfect grooves and lap joints on a table saw).

And finally, this one was a splurge, impulse buy. But something that I had wished I had on quite a few occasions when making models.

As you can see it is a pin gauge set. It is Imperial because it was a fraction of the cost of a metric set. 190 pieces of ground and laser labelled cylinders, up to 1/4″. They seem to be as accurate as my Mitutoyo micrometer can assess. It does mean that I will be committed to a moment of calculation to metric when in use. Cost? About 50 cents per piece, including the case and postage.

Fortunately for my credit card, the lockdown ended 2 days ago. I have spent a couple of short sessions in the workshop, tidying up and doing some machine repairs and maintenance. Nothing really to show. But it is nice to be back.

3D Printer Enclosure

It has been cold here during the current lockdown. And I mean temperatures. Not by American midwest standards by any means, but since we are confined to our homes except for limited predefined purposes, some days and nights are chilly. Down to 5-8ºc here.

I have been spending a lot of lockdown time doing 3D prints. And really struggling to get decent results.

Some of my GSMEE colleagues have been urging me to make an enclosure for my 3D printer. To be honest, Stuart T had urged me originally to buy a printer with an enclosure, but I pressed ahead and purchased an open structure model because I wanted the extra print size it offered. The Creality CR10s can print up to 300x300x400mm which I have fully used for my Ottoman bombard prints.

But in recent weeks, with the onset of the cold weather, I have noticed a distinct deterioration in print quality, particularly with poor layer adhesion when printing overnight, when the house heating is turned down or off.

So I decided to make an enclosure!

But, I did not have the materials on hand, and visiting hardware stores is verbotten with lockdown rules.

So, don’t laugh. This is what I cobbled together……

A couple of cardboard cartons, an artist’s A0 paper case (SWMBO hasn’t noticed it missing yet), and a blanket.

The heated printer bed is the heat source, at 50ºc. And I was surprised at the temperatures reached inside the rickety construction.

The steep temperature rise on the left is inside the enclosure after printing started. As you can see, the temperature rose from about 18ºc (room temp), fairly quickly to over 30ºc. After midnight, when the house heating was turned off there was a slow drop to 25ºc, and then a further drop to 18ºc when the printing finished and the bed self turned off.

The temperatures were measured with this gadget. A temperature/humidity logger.

Inkbird Temperature/humidity logger.

And the printing result??

The printer inside its enclosure, on the dining table.

This is the best quality print which I have had since the onset of winter weather. It is solid, water tight, and a reasonable finish. 0.2mm layer height. It is a molten metal pouring funnel, so I was not trying to get a super smooth finish, just an intact water tight object.

As soon as I can get access to Bunnings, I will make a more purposeful enclosure. Meanwhile, the cartons and blankets can remain in use.

Getting close to the first big bronze pour!

How to Pour the Bronze Barrel?

I have given some thought to how to manage the bronze pour for the barrel of the Ottoman bombard. It will be at the size limit of my potter’s oven for the PLA burnout.

The red 3D printed PLA is the barrel. The breech, although significantly shorter, weighs almost exactly the same, but being shorter, should be less problematic. The wall thickness of the breech is greater than the barrel.

I had thought that the steel cylinder would be adequately long to cast the barrel, but it is about 50mm too short when I take into account the bronze feeder reservoir which will be required. So I will add a 50mm length, probably by arc welding another bit of tube to one end. It wont matter if it is not a perfect join. I will make it waterproof with duct tape. The tape will burn off during the investment melting/burnout.

I will cast the barrel with the threaded end downmost. The molten bronze feeder reservoir will be 60mm deep which I hope will provide adequate pressure and extra molten bronze if required during cooling contraction.

I decided that the usual rubber pouring funnel (pictured above at the bottom of the steel cylinder) would not have an adequately large bronze opening or reservoir depth, so have 3D printed one in PLA. The PLA will disappear during burnout, but will leave its shape in the investment medium and become the funnel and reservoir.

I wont be using the rubber cap/funnel mold. I hope that the 3D printed one works. Despite appearances the thin flat base is watertight. As shown here the funnel is positioned as it will be when the investment medium is poured. The cone seen is not a funnel. It is a distributor for the molten bronze. When the bronze is poured the cone will be point up.

Hard to get your head around that one? It certainly was for me when designing it.

You (and I) need to remember that any space around the PLA will become investment medium. The PLA will disappear and become a void which will be filled with bronze.

This screen shot of the 3D diagram might help. This is the pouring reservoir in the pouring position. The wide disk at top is to position the print on the steel flask. The skinny cylinders are vents to release air during the bronze pour. The stepped cylinder in the middle sits on the inside lip of the barrel. The inverted cone will be solid investment to direct the bronze into the barrel void. Confused?
Maybe this will help. This is the position the PLA parts will sit inside the steel cylinder during the pour of the investment medium and later during the PLA melt/burnout.
During the bronze pour the PLA components will be voids, which the bronze will fill. (except for the widest disk at the top which will disappear.)

The 3D print took over 8 hours. 0.2mm layers, 210ºc extruder temperature, 3000mm/min. I will need to do a similar 3D print for the breech. If either or both pours fail the whole process will need to be repeated.

Still in lockdown. Cannot visit my workshop due to the 5km travel limit. So 3D designing and printing at home is fairly good use of my time.

Lockdown No. 5

A few more small jobs out of the way, and some underway.

I showed you the “large” Kant Twist clamps recently.

Now I have finished the small ones. Same pattern, just reduced by 1/3. And a different handle.

Brass pins again. Machine cut knurl was simple with a CNC rotary table. No grooves machined into the jaws. They can be done later if required.
Lathe chuck spiders are not new. I have made them from steel in the past, but I never seem to have the correct thickness. Fellow GSMEE member John Bernoth brought 3D printed versions to the last meeting, and it seemed like a great idea, so I have been printing up some too. The chuck has 20mm deep jaws, so I have printed 10, 5, 2.5 and 1.5mm thick examples. I discovered that levelling the printer bed is absolutely critical to getting consistent thicknesses. Best so far is the one at bottom which is within 0.02mm. The top one was an early one, and is only within 0.1mm, so will be redone. Notice the honeycomb infill. It has 10 surface layers top, bottom and edges, plus the infill. PLA. Quite strong, but very light. Seems a good application of 3D printing technology.

And back to the bombard. (The rib pain is easing). A 14kg crucible is on the way from UK. And I have the PLA models for the mold. I do hope that I do not need to reprint them.

The 350mm SS cylinder which will hold the PLA model and the investment medium, and eventually receive the bronze. The red barrel 315 x 107mm, and the black breech 240 x 107mm. There is almost the same weight of bronze in the barrel as the breech. The breech wall is much thicker, despite the smaller OD.

Now I am thinking about how to funnel the bronze into the mold, and where to place some air vents. Also have to work out how to drain the melted PLA during burnout cycle.

Will need to make some tongs for the new big crucible.

And for my non Australian readers, we in Victoria and NSW are in Covid lockdown again. So I have plenty of time for planning for the bronze pour.

3D Printing Difficulties

I have been attempting to print a 1:10 scale barrel of the Ottoman bombard, in PLA, so I can make a cast in jeweller’s investment, and use that to pour a bronze version of the cannon.

I borrowed a big furnace to melt the bronze, and broke 2 ribs unloading it from my vehicle. That was about a month ago. They still ache a bit, but apart from careful positioning in bed, are steadily mending. I have to sleep on my back, which would normally make my snoring unbearable, but the CPAP machine is working quite well. SWMBO absolutely insists that it is in constant use.

And I have purchased a length of 5″ stainless steel pipe to make the mold.

I have featured the Ottoman bombard in previous posts, having made a wooden version some years ago. It is over 500mm long, and 107mm diameter. In 2 pieces with a big thread joining the pieces.

Just to remind you of the appearance of the bombard. This is the wooden version. 500+mm long, 60mm bore.

I can’t really justify a bronze version. It will weigh close to 20kg. But it is a challenge. And I think that it will look more authentic in unpainted bronze.

I printed the breech part a few months ago.

It is 240mm long, and with some post printing finishing will come up fairly well. The thread will be replaced by a redesigned thread. The original male thread on the Royal Armories bombard was tapered, so I have printed a tapered PLA version and will cut off the thread pictured above and glue on the new one before casting. I have tested the tapered thread in a test piece of printed barrel with female thread (which is not tapered) and it does go on much more easily than the parallel version, so that gun maker (Orban, the Hungarian or German) knew a thing or two.

3D PRINTING THE BARREL.

The barrel is 315mm long. My printer has a maximum print size of 300x300x400 mm so I was not anticipating any problems. I knew from the slicer program that it would take 2/3 of a 1kg reel of PLA, so I bought some new transparent PLA, thinking that it might melt/vapourise more completely in the burn out cycle of the production than the coloured PLA.

So I tried to print it. I have lost count of the number of unsuccessful attempts. Each time the print would start well, but at some point, sometimes after a whole day or 2 of printing, the print would come loose from the printer base and I would have clean up the mess of PLA spaghetti, and start again. I cleaned the printer base thoroughly. Scraped it. Wiped with acetone. Re-levelled it multiple times. But every time the print would break free.

I also noticed that I was getting a lot of stringing, and lumps of PLA would form on the printed surface, cool and harden, and sometimes the print nozzle would hit the hard lumps. That is when the print would loosen from the base and eventually break free.

I have been using a 3M printing cover over the aluminium printer base, quite successfully for over a year. Maybe the cover had worn out. I looked up the P.I. for the cover, and yes, it has a stated expected life of 10 uses! So that was likely the cause of the adherence problem because I must have used that cover at least 50 times!

I had no replacement 3M cover, so I reverted to the original cover supplied with the machine, which was boro-silicate glass. Initially it worked well, with good print adherence, but the hard lumps were still forming, and when the nozzle hit them, there was enough force to break the glass plate free.

What could be causing the hard lumps?

I watched multiple YouTube videos. Re-levelled the bed again. Checked every nut and bolt on the printer for tightness with no problem found. Checked the Z axis for level.

By this stage I was contemplating buying a new printer. Maybe one of those liquid + UV light jobs. But one of those big enough to make my barrel would cost thousands. So I got a quote from a professional printing service to print the barrel…. almost $AUD600. I would have done that, but the print is destroyed in the making of the cast, and it is possible that more than one attempt of bronze casting will be required. I was considering abandoning the entire project.

One last try at a print. I replaced the 3M cover with a new cover, and started a new print with a new reel of red PLA.

All seemed to be going well.

The print was adhering solidly to the new 3m cover. The hard lumps were still appearing, but the print head ploughed through them or knocked them off completely. The problem was, that after 3 days of printing, with 10% of the barrel still to go, the multiple jarrings were producing axis shifts. The appearance was pretty bad, but I figured that I could fix it with some extensive post printing hand finishing.

By this stage the print was almost 300mm high, and I could watch the laying of the PLA extrusion from the print head directly. In retrospect I should have used a mirror to do this at a much earlier stage.

What I saw explained the issue of the hard lumps appearing.

PLA was slowly oozing from around the base of the extruder nozzle. It was gradually building up into a pea size lump, and eventually falling off onto the print face!

So, I paused the print, picked off the accumulating lump, and watched some more. The same thing happened.

Why was the base of the nozzle leaking? Another pause. Checked the tightness of the nozzle. It was totally loose. About a full turn!

Tightened it up. Resumed printing.

The next layer did not adhere at all to the previous one, because tightening the nozzle had lifted it at least one mm.

The almost completely printed barrel. Lots of stringing. No hard lumps in this picture. This is in the dining room of my house. The room has been unused since the start of Covid. Quite handy and warm for printing.

I thought that I could start a new print of the final 10% of the barrel, and glue it to the part pictured, but when I examined it, the layers were poorly adherent, and falling apart. It went into the plastics bin. I expect that the loose nozzle caused multiple print faults in x, y, and z axes.

A record of printing failures.

So, I am now 32 hours into the next attempt, with 47% completed.

See the difference? No stringing. No lumps. Quite a reasonable surface. Fingers crossed.

Kant-Twist Clamps

Now that the Model Armstrong cannon is finished, I feel able to move onto some smaller projects which have been hanging around on my to-do list.

4-5 months ago I had these parts laser cut from 3mm and 4mm plate. GSMEE members have been making the Kant Twist clamps, and over the past 3 workshop sessions I have made a pair of the larger clamps.

There are side panels for 31 large and 32 small clamps. Most were taken by GSMEE members and some went to GSMEE Facebook readers interstate. I kept parts to make 2 large and 2 small clamps.

The machining of pins and jaws was very basic so I did not record those processes. The laser cuts holes were accurate enough to be reamed to size. I found 2 annoying mistakes, neither of which was fatal. There is an extra hole in the small side arm. And the position of the pivot hole in one of the arms is about 1mm out. Not sure how that mistake crept in. Neither of these mistakes will affect the functionality of the clamps.

Completed larger clamps. They open to about 90mm.
I chose to use brass for the pins, screw thread, handles and jaws. I decided to peen the pins rather than use machine screws. I had never “peened” before, but after the first effort bent and snapped I modified my technique. The failure occurred when I used a 20 ton press to do the peening. So I drilled that pin out and next time I used a light hammer to do the peening, and that worked fine. The pins have substantial shoulders as you can see from photo above, and they were turned to be a sliding fit in the holes. Then the outer 2/3 of the holes was given a very slight taper ream. It was a 7º included angle. Then the light/medium hammer tapping to cause the pin to expand into the taper. Incidentally, when I removed the failed pin, I discovered just how secure the joint was. It was quite difficult to get it out. I had to file the protruding end completely away, then drill a substantial hole through it before it would budge with a pin punch.
I used countersunk machine screws to hold the jaws, so I can make job specific jaws in future if required. The machine screws were ground to length so they lock together in the middle where they meet. That allows the jaws to rotate if necessary to use different faces.

The taper reamer used prior to peening

I would suggest one design change to the clamps, which I will apply to the small ones when I make them. I would add a small extension to the handle boss, say about 12mm, and knurl it. That would facilitate speedy changes to opening settings, before tightening with the handles.

Time and use will tell whether my choice of brass was sensible.

I know that these clamps can be purchased on Amazon and other sites, but this was a very satisfying project, and I have no regrets about deciding to invest the time to make them.

Small Drill Bit Sharpening Jig

Small drill bits (up to 3.2mm diameter) are almost impossible to sharpen. Most of us just just buy new ones when our bits get dull. They are not expensive even in packs of 10.

But, sometimes we have parts which require sharp bits. (see recent post on installing model cannon sights). Even new bits are not necessarily correctly sharpened. I use Sutton drill bits which in small sizes cost ~$AUD18-20 for packs of 10 bits, but for crucial jobs I would like to touch up even those quality bits. The Sutton bits which I used for the cannon sights worked well, but the tense job made me very aware that in future I NEED to make sure that the bits are sharp.

So, I made a jig for sharpening small drill bits. The plans were published in Model Engineer 29 Dec 2000 and 26 Jan 2001.

It was a simple build. Took me 2 workshop sessions of about 2 hours each. I had the jig plate laser cut, very inexpensively from 2mm mild steel plate. Distributed to interested GSMEE members. The drill bit holder is an Asian copy of the English “Eclipse” pin chuck original. Also inexpensive. Came with 3 collets, to hold sizes up to 3.2 mm diameter. Cost $AUD10 inc postage. Note that the 1/4″ shaft actually measures 6.25mm diameter.

I used M2 and M3 metric fasteners in preference to the specified BA10 and BA8 fasteners.

The pin chuck should be through drilled in order to accomodate longer drill bits. The Asian pin chuck was not difficult to drill with a 3.5mm cobalt bit. It appeared to be case hardened only. And I used 2mm mild steel plate instead of the specified 16g brass plate for the jig. The wheel mounts were modified to cope with the different plate thickness.

M2 and M3 fasteners. 1cm grid.
Magnification is required to position the bit at the correct angle in the pin chuck. (the 1.5mm bit shown is not exactly at the correct angle in the staged photo above).

The plans and instructions for use are in the articles in Model Engineer listed above.

p.s. GSMEE members who intend to use the laser cut plates. The drilling positions marked by the full thickness crosses can be successfully drilled to 1.6mm and 2.5mm by using sharp drill bits at high speeds- 3000rpm, slow feed rates, and cutting liquid. I used TapMagic.

And, it works! Here I am testing a 1.5mm bit which has been sharpened with the jig. Drilling through 4mm mild steel.

Armstrong RML Cannon Sights

The sights were the final parts to be made for the model Armstrong RML.

There were reasons for delaying these items. They are tiny, easily dropped and lost, have tiny almost invisible details (to my eyes), and involve fine and very deep drilling into the barrel, on which many hours have previously been expended.

First I looked up every reference I could find about the full size originals. I could find no picture of the sights on the 80pr Armstrong, but I did find some diagrams of the sights on the Armstrong 64pr, on which the 80pr was based. Another problem was that there were rapid developments in sight technology, and I had to decide which period I would choose. The later periods (after 1880) had complexities which did not exist in 1860. In the end I just made decisions, knowing that they might not be exactly correct, but thinking that if further information surfaces I could make and install new sights.

This is the design I chose. The 64 pr had 3 pairs of sights, the 80 pr had only one pair, on the right hand side.

The next step was to drill some 2mm and 3mm holes into the barrel.