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"

Tag: model cannon

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.

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.

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 20+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.

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.

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.

The drilling setup. The barrel was held firmly between brass strips. The breech end of the barrel might need a bit more finishing.

First I milled 3mm flats. The first milling bit, solid carbide, just snapped as it bit into the barrel from the side. A HSS bit was more long lived.

A complication was that the foresight was vertical, but the hindsight was sloped 2º inwards to adjust for slight lateral deviation of the projectile which results from the rifling.

Next, a 2mm hole was drilled right through the barrel, missing the bore, and exiting through the bronze bracket which supports the elevation quadrant gear. At 40mm deep that hole qualifies as deep drilling. Tension drilling.

I did not have a long series 2mm drill bit, so I silver soldered an extension, leaving 40mm of the 2mm bit exposed. No photos of the deep drilling. I had other things on which to concentrate. The drilling was actually uneventful.


Showing the drill sitting in the hole
Fabricating the sights involved silver soldering 0.5mm brass strip to 2mm stainless steel rod. This was the soldering setup. The the sights were shaped by belt sanding and filing.

And now for some sights of the sights on site.

I will polish the sights.
Apart from dusting the base, and some final polishing, the model Armstrong cannon is now completed.

Bronze Casting a model Turkish Bombard-1

Almost finished the model Armstrong 80pr RML, and just starting another project. I have mentioned it in previous posts…. a 1:10 scale model of the 17 ton Turkish bombard, which currently resides at the Royal Armories Museum, Fort Nelson, Portsmouth, UK.

The original was in 2 pieces, to make the casting process manageable, and presumably to make transporting the monster cannon more manageable. The museum states that another reason for the screw thread join of the 2 massive parts was to separate the halves for reloading, but I can find no substantiating references for that statement. And it does not make sense to my conception of what would have been involved in the reloading process.

At 1:10 scale the model will be over 500mm long, and will presumably weigh approximately 17kg (37.5lb). Each piece will weigh 8-9kg. I will make the model in 2 pieces, for authenticity, and to make the casting more manageable, and to make the 3D printing possible. My 3D printer has a maximum model size of 300x300x400mm.

I spent several days drawing up the breech and saving it as an stl file, for the slicer (Simplify 3D) to process. The slicer predicted that the print would take 51 hours, and consume 697g (1.5lb) of PLA. I used 0.2mm layers, with 8 top, 8 bottom, and 6 side layers, and 10% fill, and since there wee some 90º overhangs, I decided to add supports.

And guess what. The print took 51 hours, and consumed most of a 1kg roll of PLA.

I chose to operate the extruder a bit hotter than normal, at 225ºc, and heated the platen to 65ºc. I wanted to make sure that this print was water tight for the moulding process, and remained adherent to the platen for the duration of the print. I accepted that the detail of the print surface would be a little coarser than could be achieved at a finer layer thickness, but the benefit would be increased water tightness.

The Ottoman Bombard at Fort Nelson. In the background is the barrel for the supergun which Saddam Hussein ordered, but was prevented from being exported from the UK.
After about a day of printing. On our dining room table (which I made many years ago).
Phew! Printing completed.
Most of what can be seen here are the supports.
It took about an hour to remove the supports. They were particularly resistant to remove from behind the pins.
I will spend a few more hours sanding and filing and filling the surfaces, before making the molds with the investment powder.

I am still drawing up the barrel. Well, actually, it is fully drawn up, but I am refining the drawing of the Arabic script which is embossed on the muzzle. It is quite difficult to convert the squiggles and patterns to vectors, which can be used to produce the STL file for the 3D printer.

The Arabic patterns and script on the muzzle. At 12, 4 and 8 are floral patterns. The calligraphy reads “Help O Allah. The Sultan Mohammed Khan son of Murad. The work of Kamina Ali in the month of Rejeb. In the year 868″. (CE. 1464). p.s. I did not previously notice the alien watching me , top right.

Who Would Like a CANNON for Christmas?

So, the first model Armstrong 80lb RML is finished. Final photographs following. I admit that some artistic license has been taken, as directed by SWMBO, and some scale details have been modified slightly in order that it is finished in time for Xmas.

Yesterday I fished out the components of the other model cannon, the “A” version, which I am making for myself, and which will be used in model engineering exhibitions. I predict that it will take another 2-3 months to complete. I am intending that it will be more rigorously an authentic scale model, and probably less pretty and decorative than the version pictured below. But it will look interesting alongside the 24lb long gun of the Nelson era, the 32lb carronade, and the huge Ottoman 1465 bombard, all to 1:10 scale.

Here are the final photographs of the “artistic” B version.

The FIRING position. The gunpowder bag and projectile have been loaded, the gun captain has set the elevation and locked it. The dog clutch has been disengaged. (the dog clutch handle is behind the squared shaft in the above photo).
After firing the recoil has pushed the carriage up the inclined chassis. The big handwheel will be used to position the carriage higher on the chassis for loading.
After swabbing to douse any embers, the gunners will lift the gunpowder bag onto the loading cradle and it will be rammed into position, then 2 of them will lift the 80lb projectile onto the cradle and ram it into position. A rope quoit stops the projectile from sliding out of the barrel. The barrel is levelled, then rolled forward into the firing position, controlling the descent with the brake. Brake lever shown here. The elevation is set and locked (locking handle on the other side), ready for another firing.
The rear bumpers were the final parts to be made and fitted. Just seen here.

When I make the sights for my “A” model, I will also make some for this one.

There is a name plate which was lasered by my colleague Stuart Tankard but that reveals a bit too much information to show here. Suffice to say, it names the cannon, a few basics specs, maker’s name, and year. It will be fastened to the wooden base. It also states “NEVER FIRED IN ANGER”.

Thankyou to all of my readers, many who have supplied useful advice and welcome encouragement. Particular thanks to Stuart Tankard for his lasering expertise and machine, and other technical advice. And thanks to SWMBO, who has warmed to this project as it approached completion, despite having absolutely no interest in weapons of destruction. She does have a good eye for form and colour. And mostly for putting up with my foul moods when things went wrong.

Now. It will be interesting to see if the recipients of this model actually like it.

Wooden Base for Model Cannon

I have machined a wooden base and I will fasten the central column of the cannon chassis to the base. The reason is that people cannot resist swivelling the cannon around on its column and the the wheels tend to mark/scratch polished surfaces. Better to mark a wooden base than a polished mantelpiece. But how to finish the surface of the base? Any polish/paint will quickly develop marks from the wheels. I have decided against making steel railway lines for this model.

I have used an Australian hardwood (mountain ash, a very hard dense wood, reclaimed from a demolished building). I am thinking that I will just oil it. The colour of the wood will darken with age, but will never be as dark as the table, which I made decades ago from Australian Iron Wood. (note, not iron bark. Iron wood. The hardest, densest wood I have ever used. And yes, I have worked with lignum vitae, and Australian red gum. The marks in the surface of the table are only in the polish. The wood is almost impossible to scratch. My kids used to dance on this table 30 years ago.)

The burn mark on the end of the base is from the belt sander. I will remove it with hand sanding before oiling.

The machined finger grips on the ends were made on my vertical mill with a steel moulding cutter intended for metal machining. It worked well.

I discussed the finish which I wanted to achieve with my resident finishes expert. SWMBO. I wanted a slightly darker, low sheen finish, which would not get scraped off with the cannon wheels.

She recommended this stuff. It is a stained, penetrating oil. Smells very chemically.

It is actually a surface repairer, rather than an overall finish but I did what I was told.

OK. That looks good. The surface will be easy to touch up if required.

Then I read the rest of the label….

!!

One down, one to go.

1:10 Model Armstrong rifled muzzle loading 80lb cannon WILL be ready for Xmas.

Apart from minor touch-ups, the model and painting is completed.

I will take some careful photos before it goes to its final home, but here are a few snaps to show how it appears with some paint and lacquer.

Oops. Forgot the big handwheel.
The gears, brake and dog clutch all work well.
and a few more chassis bolts to insert.
I extended the recoil piston rod to allow full travel of the carriage on the chassis. The join is smooth.

So, was SWMBO correct about not painting the chassis? I like the look of this finish scheme, but now have to decide what to do in that regard with the “A” model, which was put aside while I finished this one.

p.s. I weighed the model, because I was curious. The full size original barrel weighed 81.5cwt/4.1 tons plus the carriage/chassis, about 5 tons/5080kg total. The 1:10 scale model should weigh 0.1 x 0.1 x 0.1 or 1/1000th of that which would be 5kg/11lbs. It actually weighs a tad under 10kg/22lbs which is almost exactly double the predicted. It is a bit of a lump to carry around and I do NOT know where the extra weight came from. Or maybe my mathematical assumptions are incorrect.

(note added 1 March 2021. See the post added 1 March 2021. The total weight of the gun barrel, carriage, and slide – which I have been calling the chassis, was close to 10 tons! So my assumption that the model should weigh 1/1000th of the original was very close to correct!)

Pointy Projectiles

The accuracy of cannons was dramatically improved in the 19th century with several developments.

  1. The bore was machined rather than just cast, as result of the invention by Wilkinson of a powered boring machine. Incidentally, this process was also adopted by Trevithick in making steam engine cylinders, significantly improving the efficiency of steam engines.
  2. The adoption of sights, calibrated for distance, and movement of the target, instead of just eye balling along the barrel.
  3. Changing from round iron balls to cylindrical projectiles, with a pointy front and slightly rounded rear.
  4. Rifling the barrel bore, causing the projectile to rotate.
  5. Standardising the weight and granularity of the blackpowder, making shots more repeatable.
  6. Increasing the power of gunpowder by increasing the size of the “corns” which sped up the rate of combustion. This permitted flatter, more accurate trajectories.
  7. Improvements and calibration of degrees of barrel angulation.
  8. Increased research and knowledge of the science of ballistics.
  9. Increased training and professionalisation of gun crews.

The Armstrong 80lb rifled muzzle loader had a projectile which weighed, you guessed it, 80lb (36kg). A bit later cannons were categorised by the weight of the barrel. e.g., the 80lb Armstrong would have been named a 4 ton cannon. The gunpowder was standardised at 20lb per firing. The gunpowder filled silk bag, then the 80lb projectile were manually lifted onto the loader cradle, then ram rodded into position. Later, bigger cannons, needed a small crane to do the lifting, but in 1866, the 25 Armstrong 80lb cannons which were made specially for Victoria and South Australia, and were the most advanced cannons made at that time, required strong gunners to do the lifting and ramming.

My model Armstrong cannon is basically a display, rather than a working (firing) model. So, for the display, I have made some projectiles, and fake gunpowder bags. I was fortunate to find some old diagrams of both.

As you can see, for an 80lb RML cannon, the projectile is 15″ / 380mm long, and just under 6.3″ diameter. The barrel bore is 6.3″ diameter, and to cope with heat expansion the projectile must have some “windage” (a gap) to avoid jamming. The 1866 projectile has a pointy end, and a rounded rear, which is relatively aerodynamic, and similar to the form used in many modern guns.

Attached to the rear of the projectile is a (dark shaded) copper disk, which expands into the rifling grooves after firing, and further reduces the windage, and causes the projectile to rotate. The copper disk separates from the projectile after they leave the barrel, and it falls to earth. The best examples of the copper “gas checks” have been retrieved from the sea, in front of shore batteries where these cannons were located.

Before gas checks were introduced, the projectiles had copper studs attached to their exterior. The studs fitted into the rifling grooves. The studs were effective at causing the projectile to spin, but they caused rapid wear of the cannon barrel, excessive drag and lower muzzle velocity of the projectile, and were slower to load. The 25 Victorian Armstrong 80lb RML cannons were designed so that studded projectiles could NOT be used. (n.b. note added 7 Jan 2021… that last sentence is incorrect. The 80lb RML’s would have used studded projectiles until mid 1880’s, and then changed to gas check projectiles. instructions were issued then that studded projectiles should not be used.)

The following drawing shows a silk bag, containing the gunpowder. It also shows the central wooden rod which prevented the bag from bursting during ramming. This powder charge is for a 10″ RML, so it is bigger and heavier than the one for the Armstrong 6.3″ RML, but the design is essentially the same.

After loading and aiming, the gunner would perforate the silk bag with a long spike, then insert a quill or later a copper tube, full of fine gunpowder which extended through the vent from the touch hole to the perforated silk bag. Royal Gun Factory experiments showed that the best firings occurred if the silk bag was perforated about half way along the cylindrical bag, so the vent and touch hole were located at that point.

Some scaled projectiles in mild steel and copper gas checks. Some more shaping required for the gas checks, then they will be attached with gunmetal (bronze) pins to the projectiles. The 1866 projectiles had a cast iron case, were packed with explosive, and a fuze. The book is a reprint of an 1897 publication. It has been consulted many times, as you can see from the workshop stains.

The method of igniting the gunpowder will be described in a future post.

Assembly Modules

First, I have decided to NOT rivet the final joins of the chassis. Instead I am using dome head stainless steel bolts and nuts. The main reason is that the other end of the rivets are in impossibly small (for me) cavities and spaces, and I could predict that the final riveting result would be horrible. Even using threaded rivets would be incredibly difficult. This decision does cause me to reflect on the 1866 cannon builders who managed such perfect results with red hot rivets in confined spaces, and again, to be awed.

As you can see, the bolt heads are same shape and size as the 2mm copper rivets. My intention was to paint the rivets and the bolts (after filling the hex holes) and then they would be virtually indistinguishable. However, that plan was blown out of the water by SWMBO. (read on).
The copper rivets and stainless bolts. Not kosher. But interesting?

To divert, back to the painting.

Question. When painting a model, is it best to assemble the whole model then paint, or to completely disassemble every part, paint the parts then reassemble?

1. Disassemble and paint the parts then reassemble. This results in complete paint coverage of all parts. It results in clean separation of different coloured parts. Mistakes involve limited areas and are easier to correct. However, the thickness of the paint can alter carefully machined tolerances. And surfaces can be painted which were intended to be unpainted.

2. Assemble the entire model, then paint. This can make some recesses, corners and hidden areas difficult to access. But the appearance of the entire model can be assessed as the painting progresses, and major mistakes in colour choice can be corrected. The painting process does not alter dimensions or fitting together of components. But paint edges and joins can be difficult to keep neat and straight, particularly in my inexpert hands.

3. (Obviously what I chose to do). Partial assembly, into modules, then paint the modules separately. This has the advantages of both 1 and 2. The modules can be stacked together to periodically assess the results. The modules are smaller than the complete model, and easier to handle. Difficult decisions regarding colour, or whether to paint at all, can be deferred until the easier parts are painted, and some idea of appearance ascertained progressively.

So that is what I am doing. I have painted the bottom part of the chassis, and the carriage. Etch primer at this time, but already firming up ideas about final colour. And my colour and design expert advisor (SWMBO) has had some input into this decision.

These are the main modules, 4 of them. The barrel assembly is stainless steel and it will not be painted. At the rear are the carriage and bottom part of the chassis, which have been primed. The main chassis beams containing the movement gears are unpainted. The carriage looks naked without its bling.

At this stage, I asked for advice from SWMBO. She has suggested that the primed modules should be painted satin black, which should contrast nicely with the brass/bronze components. Avoiding gloss will minimise the finishing defects. Some filling of defects will be required in any case. The black colour will be tested on the carriage, and if it looks OK, the chassis subframe will receive the same colour.

SWMBO’s most interesting suggestion is to NOT paint the main chassis beams at all! Well, a clear lacquer will be required to prevent rust.

But. What about disguising the copper rivets/stainless bolts?

SWMBO: “they look interesting. Leave them.”

Me: “but, but, but, they do not look authentic.”

SWMBO: “This has to look like a work of art, otherwise it will be just a boring dust gatherer.”

She wins.

Warts and All

A few more photos of the model Armstrong RML cannon. Close ups which are useful to me, because they show up defects in the finish which need attention before painting.

Makers mark (mine) to be added to the recoil tube cap. And rubber washer to the bumpers.
Screws and bolts to be replaced with rivets
Metal polishing required for the muzzle
Oil holes for the shaft bearings, and replace the wonky rivets
File and finish the trunnion cap keys
finishing and polishing the loader cradle.
ditto more finishing.
Attach the left side buffers. And make chassis wheel axles. Those M5 hex screws are wrong.
Distance hides a multitude of faults

Sights Set On Completion

Today the gunners’ platform at the rear of the chassis was completed and fitted. It has vertical handles at each side, presumably for the gunners to steady themselves, while aiming the cannon.

The platform, ready to be attached to the chassis. The wood here is Australian Jarrah. The handles are stainless steel, discoloured from silver soldering them to the side brackets. They will eventually be painted. ps. a day later I decided that the fasteners were too big, so I have replaced them with something more appropriate. Pics later.
The platform in position. This photo shows up my first efforts at riveting. Some of those rivets will be replaced when everything is disassembled prior to painting. Those brass nuts holding the wooden boards are too big and will be replaced also.

So, just 2 more parts to be made for this model cannon. Those are the sights.

The information which I have to base the sights on is a bit sketchy. But I do have photos showing these cylindrical holes in the Port Fairy cannons….

The sights are placed in the holes in the right hand trunnion shoulder, and in the breech.

After extensive searching I found several books which were published in the 19th century. This is the best diagram which I found of the rear sight. It is calibrated vertically up to 3600 yards, and there are lateral adjustments to take into account speed of movement of the enemy. The sight is angled at 2+º to the left to compensate for the rifling, which causes the projectile to deviate to the right. The front sight is located in a relatively shallow cylindrical hole. The front sight is a fairly simple point.

Fitting the Loader.

The bracket is now bolted to the chassis. The arm is stainless steel, and the top bracket is silver soldered to the arm. The loader cradle is bolted to the top bracket, the angle being determined with a neat fitting rod inside the bore. The rod looks interesting, no? I will turn up a projectile to sit there.

Then I fitted the bracket which restrains the movements of the elevation gear lock-release…

This is the “locked” position. The handle drops into a recess. The bracket looks a little rough in this magnified view. A bit more filing and sanding required. A simple curved piece encloses the handle. I will make and fit that tomorrow.

So those are the last major parts to be fitted to the cannon. Oops. I forgot. I need to make the aiming sights, and bore the holes in the barrel to hold them. None of the cannons which I have inspected have exisiting sights, presumably stolen-souvenired, but some 19th century publications have good diagrams which I will be able use to make scaled versions.

I will add a rear wooden platform, and the eye bolts.

Then a complete teardown, painting some parts, polishing others.

33.9/34 Not Bad.

It was a bit too warm for casting bronze today. 33ºc/91.4f. But I went ahead. It was sweaty.

I had installed a new thermocouple in the potters oven and it performed flawlessly. Fumes from burning out the PLA and wax from the mold had caused the older thermocouple to behave erratically, but the new stainless steel type was unaffected.

And, as I displayed yesterday, I had made a very ambitious tree with 32 parts to be cast, and a second tree with 2 largish parts.

No vents. No vacuuming of the melt. Just a straight pour.

A few minutes after the pour, the bronze is still at a beautiful fluorescent red heat.
The cast 2 trees. NO bubbles (I painted the PLA trees with a slurry of investment before the investment pour). All parts look perfect, except for a tiny area of moth eaten edge on one of the parts in the top tree. Too small to show up, and quite repairable.
The other side. Not much surface oxidation (phosphor copper used).

So, a very successful pour. Some careful hand sawing required to cut off the parts.

More Gearing Up, and more to come.

This was 4 days ago.
Today. Re the gears on the right, bottom row…. one was machined from bar stock, the other was cast, had the outer ring removed, and a new ring soldered on, then the teeth were cut. Can you pick which is which? And all of the round gears have spent 3 hours in the gemstone tumbler to remove sharp edges. The tumbling has reduced the surface oxidation on the large gear castings, but some more time required to totally remove it.
CNC milling the spokes in one of the intermediate gears. Neat job, but the internal corners with fillets are not really kosher. This gear is barely visible in the finished model.

And the gears with ratchets attached need 2 mates. I tried to make them yesterday, but we had a wild day with thunderstorms and high winds, and my machines were playing up. I might get back to them today. (the ratchets can be seen in the header photo).

In country Victoria we are out of level 3 lockdown! Hooray! Still can’t see family from Melbourne, and minor restrictions on visiting local friends, and need to wear masks when out and about. But things are on the improve. I doubt that we have seen the last of the virus however.

Trunnion Mounts -3

I did not expect these mounts to require a third day session, and they are still not finished!

I discovered that two of the drilled holes in each bracket were in the wrong position, by approx 1mm.  That is a really bothersome error, because the correct position includes half of the existing hole.

I managed the problem by threading the errant holes, and Loctite gluing in some threaded rod.  Each rod was trimmed flush with the surfaces.   Then drilling the new hole, partly through the Loctited metal patch.  That fix worked well.

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Threaded rod glued into the errant hole.  Trimmed flush later.  Then redrilled correctly.

 

THE TRUNNION PINS.

The pins hold the trunnion caps in place.  And they took another whole day to make and install.   Ah….  just as well I enjoy all of this.  They are tiny, and I spent at least 50% of the time looking for them on the workshop floor after accidentally dropping them on several occasions.

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Milling the pin handles from 2mm steel.  The handles ended up at 7mm long.  The holes were drilled before the outlines were cut.  Then the tabs were ground off using my newly made belt sander belt.  The belt lasted 15 minutes before the belt itself tore, with the join still intact!

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Then some delicate silver soldering of a ring to attach a securing chain later, then the pin shaft itself.  The wire through the ring is just to hold it in position during soldering.

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And that is one of the 8 pins made.  I will polish them in a gemstone tumbler next session.

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On the model, the pins are jammed into position with a cam action, after some filing-shaping.  On the original cannon there was a small protrusion on the inner end of the pin shaft, which fitted through a slot in the side of the carriage.  I could not figure out a method of making such a tiny slot (1mm wide x 1mm deep) through 4mm of steel plus 2mm of brass, but the cam action seems effective.    I will attach some chain soon, because I do not wish to make any more of these.  And yes, the pins handles are slightly over-scaled, but I think not outlandishly so.

So, apart from polishing riveting and painting, I think that the trunnion mounts are finished.

Now planning to make the gear train for the carriage positioning on the chassis, and the pinion, quadrant gear, and bevel gears for the barrel elevation.  We are currently in level 3 lockdown for Covid containment, with level 4 looking likely any day, so obtaining brass for the biggest gears is difficult.  I am considering workarounds.  Apparently community anxiety and depression, family violence, and even suicides are mounting.  When I am in the workshop I am in a different world, thank goodness.

 

 

 

 

 

 

 

Trunnion Mounts -2

It took a whole day making and fitting  the top caps of the trunnion mounts from brass.

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A 76 x 76mm piece of brass was milled to 10mm thickness.  The trunnion straps will finish at 9.5mm , giving me a 0.5mm machining allowance.

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The 4 straps were cut out using a new 4mm endmill.  Rounded internal corners were milled square, and the bottom tabs were milled to 2mm thickness.

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2mm wide slots were milled into the brackets, and ends of the slots were filed square.  None of my rifling files were small enough, so I ground one to size, leaving the faces and one edge  intact.

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Trunnion mount almost finished.  Pins in the tags to come, and they will pull the strap down tight with a cam action.  The half circle line on the bottom bearing is a painting border to delineate the bottom bracket from the bronze bearing surface which will not be painted.  If you inspect the full size trunnion in the previous post you will see what I mean.

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Now I can take some measurements of the model, and start the barrel elevating gear.  There are 4 gears to be cut, including  bevel gears, handle, shafts, gear case, and some complex mounts.

Recovering from Friction Welding

Back to the model Armstrong cannon carriage this afternoon, and fitting 2 internal transoms, which provide rigidity to the carriage.

The transoms had been laser cut some months ago.  I cut the floor from 2.8mm stainless steel.

Each transom is attached to the sides and floor by angle iron, 2mm thick.  In the original cannons the angle iron was mitred at the corners, and for this model “A” carriage I decided to try to replicate the mitres.

The angle iron was again bandsawn from RSS tube and milled to 10x10mm.  I used the following setup to form the 45º angles…

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This is the Eccentric Engineering tool sharpening arm, set up to 45º on my RadiusMaster belt sander, about to form mitre angles on the angle iron resting to the right.

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The Angle iron pieces were glued to their respective transoms, and 2mm holes drilled.  Bolts progressively inserted.  The lengths and cutouts will be trimmed later.

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Then milled and filed the corners until the parts fitted neatly into the carriage.  Rivets will be inserted later.

 

…and for your interest/amusement, depending on your UFO opinion…  Listen to the information, and try to ignore the appearance of the narrator.

 

….and do I think that UFO’s are real?    I would say that my “belief” has risen from 95% to 99% YES.   One of my readers, with whom I have spoken directly, and for whom I have no doubts about personal veracity, has seen one at close quarters.  Do I think that they are of non human origin?  A bit less positive about that one, but it does seem more likely than not.  Waiting to see if and what NYT does publish.

 

Friction Welding

Friction welding is a technique which is used in industry.  It involves rotating 2 metal surfaces against each other, under considerable pressure.  The heat generated from the friction is enough to make the contact surfaces to become red hot, then melt together.   There is a funny and instructive YouTube video on the subject by AVE.

I had a costly and unintended demonstration of friction welding in my workshop yesterday.  I was drilling multiple small holes in the 2mm thick sides of the model Armstrong cannon, when, somehow, I activated the Z axis downward in fast motion.  Probably I miskeyed G0 instead of G1.

The hole was drilled in a fraction of a second and the chuck continued downward.  My reflexes are not TOO bad, but by the time I hit the big red button, the bottom of the drill chuck was grinding into and bending the workpiece.  Which was glowing red hot!

“Oh Dear”! (Or something along those lines.)

I could tell at a glance that the workpiece had been destroyed.  I had a spare piece, so it was going to cost some time to repeat the work already spent on the part, probably at least a day.

But that was only the beginning.

I backed off the quill, and tried to remove the workpiece from the of the chuck.  It would not budge, so I released the 2mm drill bit (actually a carbide end mill) from the chuck.   Well, I tried, but the chuck key would not rotate.  The chuck was frozen solid.  So I went and had a cup of coffee.

On return, it was apparent that the workpiece was welded to the end of the chuck, and the chuck jaws were welded together at the tips.

So, I released the chuck and its arbor from the mill, and broke off the workpiece from the chuck with a hammer.  The weld and the drill bit broke.  But the jaws of the chuck were still welded together.

You might recall that I had accidentally destroyed an expensive Japanese chuck some months back, and this one was its “temporary” replacement.  Obviously I will need to buy a replacement this time, but I am in the middle of my cannon build, and want to get on with it.  What to do?

On close inspection the weld between the jaws stopped about 3mm from the jaw tips.  It involved the surfaces between the jaws and the still present carbide drill shank, and the sides of the jaws.   So I ground about 3mm off the ends the jaws until they started to move.  Then used a tiny grinding wheel in my Dremel to remove most of the weld between the sides of the jaws.   At this stage the chuck is looking very ugly, but it works in a fashion, and I was able to resume my drilling.   Very carefully.

I did straighten the bent workpiece, but it is RS.  I spent the remainder of the day using my spare workpiece, repeating the lost work.    No photos of the damage.  I was not in the mood.

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These are the sides of the second carriage.  For this one I am drilling the holes in both pieces simultaneously, by clamping, and then bolting them together.   Pretty obviously a better method.  Sometimes I am slow learner.  But I do try to not make the same mistake more than 3 times in a row.

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The “B” carriage on the left, and work to date on the “A” carriage on the right.  The bolts will eventually be replaced with rivets.

BTW,  I have de-monetised this blog.  You should not see any more advertisements.  I noted that the income from the ads from the one post on which they appeared, was one cent.  Yep.  One cent.  If I had monetised the site from its beginning, 6 years ago, I would have earned approximately $AUD6 dollars.  Nuf said.

Meanwhile, I discovered some more videos from posts 5-6 years ago.  I have deleted the videos.    A pity about that, but it has created some more storage space and allows me to continue to post on the current plan.

Carriage Assembly, and Gun Spiking.

If you have been following the build of the model Armstrong cannon, you might remember that most of the steel panels for the carriage were laser cut a few months ago. In the past few days I have been drilling dozens of 2mm holes, ready for final riveting.  Meanwhile the parts are held together with 2mm bolts and nuts.  I expect that the rivets will not be installed until I can see that everything fits and works as it should.

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Only a few fasteners so far, but it is surprisingly rigid.

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The angle iron is cut from the corners of rectangular section tube with 2mm wall thickness.  It does require some more finishing and rounding off, but the scale is accurate.  The big hole is to allow the hydraulic recoil tube to be inserted.  The recoil cylinder will be 18mm diameter.

SWMBO’s comment….  “It looks like it is made from Meccano”.  I guess that there are a lot of holes.

Meanwhile I have discovered an excellent reference source, published in 1879.  It is a free book, available online at Google Books.  “Treatise on the Construction and Manufacture of Ordnance in the British Service”.  517 pages.  Original price 9 shillings.  It is full of gems for the cannon modeller.  As an example, this is a drawing of the sights on the 64 pounder RML converted to 80 pounder.  You will see that the barrel shape is different from the one which I am modelling, which is a mark 3.  But it is probable that the sights remained the same as those pictured.  A great find, with enough detail for me to scale down and model.

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Note that the sight on the right is not vertical, but sloped at approximately 2º.  That is to compensate for the slight deflection of the projectile to the right, caused by the rifling.

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From the same book, a detailed description of the Vent / touch hole / ignition hole.  It was NOT just a simple hole drilled into the barrel, but a copper cylinder which was threaded into the barrel.  The touch hole was drilled through the copper.  The reason for this was that the touch hole gradually became bigger with use, and needed replacement after a certain number of firings.  It also allowed repair of the touch hole if the gun was “spiked” by the opposition, but that was a major exercise which required specialist knowledge and tools, and a return to the factory or one of the 5 workshops listed above.

Model Armstrong Gun Cypher

Yesterday I spent some time with 600 grit emery paper on the barrel.  A bit more elbow grease is required, but I took some pics of the progress….

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From the left, the sighting line called the “line of metal”.  There will be a corresponding line on the muzzle.  Next is the weight of the barrel in hundredweight.  81cwt = 4 imperial tons plus one cwt plus 2/4ths of a cwt plus zero pounds.  One hundredweight = 112 lbs, so this barrel weighs 9128lb / 4140kg.   The arrows indicate that the barrel has been “proofed” and accepted for service and also possibly mark the end of bore.  The dot would be where the “vent” would be located (the ignition or touch hole) usually about half way along the powder cartridge.  Then the reigning monarch’s cypher.  In this case, Queen Victoria, with her motto, that of the Order of the Garter.  HONI SOIT QUI MAL Y PENSE.  The translation from French is  “Shame to him who thinks ill of it” (“it” being the Order of the Garter)

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The Royal Gun Factory number of this barrel, and axis lines.  One reference stated that they mark the centre of gravity of the barrel, but according to my assessment, the COG is well behind this point.

The other trunnion marks are yet to be lasered.  Maybe late next week.

I am delighted with the quality of the laser “engraving”.  It is sharp, crisp and finely detailed.  Again, thanks to Stuart Tankard for the use of his laser, and for operating it.

How were Trunnions Joined to 1866 Barrels? Correction of a previous post.

The earliest cast cannon barrels were cast in one piece, and the trunnions were included in the casting.

By 1866 however, large barrels were made from 4 or more separate pieces, which were heat shrunk together, and additionally forge welded together.

The following information comes from “Naval Gunnery” by Captain H. Garbett, published in 1897.

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The diagram is of a 64lb Armstrong rifled muzzle loader.  The 80 lb muzzle loader, which I am modelling, was very similar to, and based on the 64lb gun, except that the diameters of the sections were larger, giving greater wall thickness.

The “A” tube, containing the bore,  was made from best quality forged steel, in one piece, although earlier models used the “coil” method described below, and earlier than that it was wrought iron.  It was permanently closed at the breech, but in slightly later models it was open, sealed with a copper disk which was held against the cascabel.  The A tube was bored and rifled after assembly of all of the barrel pieces.

The “B” tube, or tapered chase was heat shrunk onto the “A” tube.  It was a coil construction. (see below).

The “Breech Coil” had 3 components, plus a cascable which screwed into place with a deep, asymmetric thread.  One of the components was the “trunnion ring”, which was welded to, and separated the other 2 components.

“COIL” TUBES.

When steel is forged into a strip, apparently it is strongest along its length due to the orientation of the crystalline structure.   It was discovered that the strongest cannon barrels were made from long strips of forged iron or steel (up to 200 feet long), which were then wound around a mandrel, while red hot, forming a cylinder.  The red hot coil was then hammer welded into a solid cylindrical mass, with most of the steel crystals aligned circumferentially.  It was then machined into its final shape, with allowance for final heat shrinkage onto its mates.

 

The “TRUNNION RING”.

The trunnion ring was forged from a single billet of steel.  Two holes were punched through the red hot billet, expanding the sides.  Further hammering shaped the trunnions from the lateral expansions.  The final shape was then machined.

The three breech pieces were forge welded together, and heat shrunk onto the “A” tube and the “B” tube.  I could not discover the construction sequence of welding/shrinking these components.

This post is to correct an earlier post about the trunnions in the Armstrong cannon  construction, in which I stated that the trunnions were heat shrunk into the barrel.  The incorrect implication was that the trunnions were heat shrunk into holes in the barrel sides.  My recent reading indicated that the “trunnion holes” method, which I used in my model, was NOT the method used in 1866.  I am not losing sleep over this lack of authenticity in construction of my model.  One of many compromises which are made when scale modelling.

 

 

Lasering the Model Armstrong Cannon

This is the Queen Victoria emblem and motto on the original cannon at Port Fairy, Victoria.

3349 emblem

The “Victoria Regina” emblem, and Order of the Garter slogan motto.

And this is what is now lasered onto the model cannon..

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Pretty good, Hey?  On the model, the emblem is 20x12mm.    It was downloaded from the internet, edited with Corel draw, saved as a BMP file, and then lasered onto the steel model barrel.   This is a photo of the emblem on the model cannon.  The rectangular background will disappear with polishing.

It was made with a 30 watt fibre laser, driven by its owner, Stuart Tankard.  It took about 30 minutes, 200 passes.   Shows up my substandard turning.

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Shows the emblem appearing after 100+ passes.

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and this is an enlarged image of part the laser engraving.

I have some videos of the process, and I will make them available after some editing.

This was incredibly exciting.  The model cannon requires more polishing, and colouring with a gun blacking chemical.

We also engraved the cannon weight, sight marks, and year of manufacture on the trunnions.  I will post those photos when available.

 

 

and some Carriage Wheels….

The wheels on the carriage, not the chassis.

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I made 20 of these, 20mm diameter,

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The small cap screw bolts will be replaced with solid rivets.

The wheel axles are yet to be made and pinned.  (the Philips head bolts will replaced with solid pins and washers, and held with taper pins.)

And just to remind you of the appearance I am aiming for…

whole cannon R obl

I do wonder about the original colour of these 1866 cannons.  The rusty iron colour has some attraction, but I would be certain that it is not original.  So far I have had no luck finding out what the original colours were.

Firing a Model Cannon

If you want to watch a video of a model cannon being fired, try YouTube.  Or you could watch the following video, sent to me by one of my readers.  This is a slightly larger scale than my model, and a breech loader.  Superbly built.  Click on the arrow to watch it.

When anyone finds out that I am building a model cannon, the inevitable question arises “are you going to fire it?”

Up until recently my answer was “no”, because,  1. I do not have a shooter’s licence, 2. I did not intend to register the cannon and 3. Australia’s gun laws which I support, are strict and policed.

If a model cannon is capable of being fired, it must be registered.  As an owner built gun, it would have to be “proved”, i.e.  be inspected by a gun expert, and have some proving shots with powder alone, powder doubled alone, powder plus shot, double powder plus shot, and finally double powder plus double shot.  Then the gun is certified for the particular weight of powder plus shot.  I think that I got that sequence right.  It was explained to me by a gun testing expert recently.

For a model cannon not required to be registered it must be incapable of being fired.  For one such such as I am building, a muzzle loading, black powder cannon, that would mean not drilling the touch hole.  In my case I could have the appearance of a touch hole, by making a dot at the site, but no drilling.

To investigate the situation, I have checked the Victorian Government website, spoken to police, and spoken to a firearms safety course instructor.  I also visited a shooting range where a blackpowder gun club was having a target shoot.  Members were shooting black powder guns and rifles at targets 50-100 meters distant.

About 50 years ago I was in the Citizens Military Forces, a university infantry company, and had instruction and practice in using a 7.62mm SLR, an F7 submachine gun, and an M60 machine gun.

My point is that the black powder guns were VERY loud.  Painfully loud in fact, until ear plugs were fitted.  Substantially louder than I remembered SLR’s, F7’s or M60’s.  But maybe I have just forgotten.  And the blackpowder shots were accompanied by a gout of flame, and a large puff of smoke.  Spectacular, in fact.

Then, under the close supervision of a gun owner, I fired a black powder hunting rifle myself.  It was loaded by the owner, using a ram rod for the charge, and a mallet then ram rod for the ball.  2 triggers.  The first was a heavy pull to ready the shot.  The second was a hair trigger to fire it.  And hair trigger it was.  Just a touch and it fired.   Despite the BANG, some fire and smoke, and the instantaneous puff of dirt where I had aimed, the recoil was minimal, more of a firm push against the shoulder.  It was an interesting and exciting experience.  Less smoke and flame than the other blackpowder guns nearby, but maybe being a hunting gun, he had used a more modern powder.  The following short video shows my son in law taking instruction.

I have put in an application for the firearms safety course which is supervised by the Victorian Police.  Then there is a 2 part multi choice examination, with no incorrect answers permitted on critical questions, and 18/20 (I think) for the rest.  If passed, there is a criminal history check, and references required.  Then a compulsory 4 week wait.

I will get the shooter’s licence, to keep my options open, but have not yet decided about registering the model cannon.  It would be nice to have a video of it being fired, for this blog, but it is very likely that it would be a once only event.  My interest in the cannon is its historical associations, and the technology, plus the challenges of building it.

If the cannon is capable of being fired, it would have to be registered indefinitely, and the owner would need a shooters licence.  After all of the time and effort in its research and construction I  would hope that someone in my family would eventually own it, so I am thinking that I will not make a touch hole, and make it incapable of being fired.  Another possibility which I will explore, is to register the cannon, make a video, then make it incapable of being fired by partly filling the bore and touch hole with molten metal then deregistering it.

Meanwhile it will have no touch hole.

 

 

 

The (non) gripping power of rubber

In order to increase the head pressure of molten aluminium during my casting pours, I increased the height of the casting cylinder to 250mm (previously 100 to 150mm).

That meant that the weight of the casting investment mix increased to 5.25kg. per 250mm cylinder.

This was the result today, when I poured the investment mix, then moved the cylinder with the rubber cap at the bottom.  It would have been OK if I had waited for the mixture to set. (about 20″).

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The rubber end cap slipped off, the investment mixture came out, the 3D printed parts tree fell apart, and an horrendous mess resulted.

After a barrage of unprintable expressions, I hosed the 3D prints down (outside), and washed the cylinder and end cap (outside).

By then the mess on the bench and floor had set, so I was able to scoop most of it up with a BBQ spatula.  Then multiple wipe downs to get the very fine powder off the surfaces.

I still wanted to prepare the moulding cylinder(s), and for some reason I had lost my desire to use the 250mm cylinder, so I made 2 trees with the parts, and split them into two 150mm cylinders.   Without further incident.

While waiting for the investment mixture to set, I did some further work on the previously cast parts.

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Applying some JB Weld  onto one of the cast rear wheel bracket and column assemblies.

Lost PLA Casting – 3rd pour

Today I attempted another aluminium casting session with trees that I had made 2 days ago.  More wheel forks, and barrel trolley brackets.  16 parts altogether.

And this time I installed air release vents, following my previous poor results, and at the suggestion of reader Rob R.

I also made some 50mm extensions of the pouring funnel, to increase the head of melt pressure.  The extensions were “add ons” rather than designed into the system, and the molten aluminium leaked between the extension and the main flask with the tree, so I doubt that they were very effective.

BUT!  Of the 16 parts on the trees, 14 were good to excellent, and only 2 showed any voids, and I assess one of those as repairable.  So, 15/16 is very pleasing.  I feel that I am closer to getting good results every time, if I can make an effective system of increasing the delivery pressure of the molten aluminium.

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These are the extension pieces to the funnels on the investment flasks.  The shape was made with the plastic funnel.  If I had positioned them before the investment plaster had set hard they might have worked better, but as they just sat on top of the already hardened plaster, the join leaked molten aluminium rather badly.  I have a different system in mind for my next pour.

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Previous failures were cut up and thrown into the melt.

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See the tiny silver dots surrounding the central funnel.  That proves that the air vents functioned as intended.

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The aluminium trees.  Not very pretty, but delightful to see.  10 parts on the top one, 6 on the other.  It is odd to see the wax spaghetti turn into aluminium spaghetti.   I will separate the parts tomorrow.

And while the investment burnout and baking was proceeding, I worked on previously cast parts.

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The centre columns have beep painted with etch primer.  A little more filling required, then I will use the best 2 on the models.   The 2 bracket and column assemblies on the right were initially considered unusable due to large voids, but I used some aluminium solder to fill the defects, and they might possibly be OK.  The 2 on the left just need some tidying, machining removal of  melt tubes, and minimal filling.

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I will probably remake this one, but will continue to salvage it and see how well it comes up.  Note the solder fill on the RHS.   That will not be seen on the model.

One more melt and pour, and that should be the last of the castings made for the model Armstrong cannons.  It has been a challenge, and lots to learn, but very interesting and very satisfying.

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Finally for today’s post…  I noticed some black marks on the normally pristine white wall above the casting bench.  They extend about 4 meters above the floor.  Do you know what they are?  The paint has been melted off the wall by bits of flying molten brass, resulting from the steam explosion 2 days ago!

Many thanks to Rob R for his spot on suggestion about the air vents.

Video of Casting Small Complex Cannon Parts

This video was taken and edited by my daughter Eleanor.  I was doing an aluminium pour of some parts for the Armstrong RML cannon, explaining the process to her.  I was hardly aware that she was videoing, so the interaction is conversational.

Although the pour was not a success because none of the parts were good enough to use, it does show the process as seen by someone who previously knew nothing about it.

 

 

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There is also a 20 minute video of the whole process which I will add to this post when it is available.

Reader Rob has suggested that the positions of the defects suggests that air entrapment is the cause of the voids and that the fix is to position some vents at the positions at risk.  I will try that with my next pour.  Thanks Rob.

Here is the 22 minute video.  Just as recorded.  Not planned or edited.

 

 

 

 

 

 

 

TURKISH BOMBARD – a-post-script. And metal casting setup ready.

I made this 1:10 scale model of the Turkish Bombard which currently resides in the Royal Armories Museum, Portsmouth, in 2016.  I specify “currently” because I originally saw this cannon in 1979 at The Tower of London.  And long before that it was used in Turkey, guarding the Dardanelles.  Quite likely used in anger in 1805 against a British fleet, approximately 340 years after it was made for Sultan Mehmet “the conquerer”. 

And I re-visited the original in May 2019. It seems like half a lifetime ago. Mainly I visited the UK to see the Trevithick dredger engine in the London Science Museum, but the Turkish bombard was the second reason. I could not find a photograph of the touch-hole in the bombard anywhere. And my requests to the museum went unanswered.

The original bombard in the Royal Armories Museum, Portsmouth, UK.

So, here is my photograph of the touch hole, in case anyone else is inclined to make a model. I guarantee that this is the only photo of the touch hole which you will find, with my hand anyway.

The Turkish bombard touch hole
My 1:10 scale model of the bombard. I still have not added the touch hole.
The Arabic script around the muzzle. Not as good as in the original. But as good as I could manage in 2016.
and the large thread between the barrel segments


So, I made this model, in wood, as a practice run, intending to make a bronze model eventually.

The reason for this post script is that I had a question from a reader about a remark which I had made in 2016. And I could not find my original photographs. So I took some more, as you have seen.

And……… very excited to announce that I now have a foundry setup, and could possibly make a bronze example of the bombard. But first I intend to obtain some casting skills, by making parts for my 1:10 Armstrong cannon.

I replaced the analogue controller with a digital type in the potter’s oven which I had recently purchased, and today my wiring was checked by an expert before we ran a test run. (thanks Stuart!) All good, up to 750ºC, which is enough for preparing the investment molds.

Here is a shot of the oven, and the metal melting furnace.

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from the right, the melting furnace which should be adequate for 3kg of brass/bronze,  and the investment oven. The oven might also be useful for metal tempering. Note the Hebel bricks behind the oven.

Hopefully, the first attempt at a casting session in a couple of days.

 

Armstrong Cannon Wheel Assemblies -2

rear wheel and support

There are 3 major components of each wheel assembly, plus the wheel, axle, and king pin.

The wheels, axles and king pins are straight forward metal turning, but the other 3, the wheel bracket, the king pin post, and the chassis bracket, are castings in the original.

For my 1:10 model I am planning to cast the king pin column, and the wheel bracket.  But I will fabricate the chassis brackets.

There is one chassis bracket for each of the 4 chassis wheels, and they are all different.  Front different from rear, left and right hand versions.  And each one has angles of 90º, 30º, 20º, 6º, 2º so the machining was quite a mental exercise.  No major stuff ups though.

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Here is the main component of the left hand rear chassis bracket, being held in position.  It will be bolted on later, and have several flanges silver soldered to it.   Those M2 cap screws will be replaced by rivets eventually.

Meanwhile, having decided to cast the king pin casing, and the wheel bracket, I spent many pleasant hours (or was it days?), drawing them.  Then yesterday, I 3D printed an example of the king pin casings.

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2.5 hours to print PLA examples of rear (left) and front king pin casings.  I need to see the original cannon to check some details before committing to cast these in bronze.  The PLA parts will disappear during during the casting process.  (A pity.  They are quite attractive No?)  You can see why I chose not to machine them out of bar stock.   3 pin holes in the left hand print ? the result of not storing the PLA spool in a dehumidified container.

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So, it might not look like several days of computer and workshop time, but that is how long it has taken.

In Australia we have had some easing of Covid-19 restrictions, but not opening of museums or historic collections of cannons.  So I still cannot go to Warnambool (a 2.5 hour drive) to check details on their Armstrong 80 pounder rifled muzzle loader.  Flagstaff Hill Maritime Museum does not answer their phone.  Hmmm.  Maybe I could climb the fence and sneak in……    but maybe not.

Armstrong Cannon Chassis Wheel Assemblies

The steel chassis is virtually finished, although I am delaying inserting the final rivets which join the girders together, in case I need access to the individual girders for more machining or drilling.

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The 2 chassis’ are not identical.  Can you spot the differences?  And still waiting for more rivets to arrive.  The copper colour on the front one resulted from dipping it in well used sulphuric acid after some silver soldering.

 

Considering how to model these wheel assemblies…..

front wheel and mounts

The front wheel assemblies

rear wheel and support

The rear wheel assemblies

The rear wheels and supports are larger than the front ones.  But the top views are essentially the same.  The wheels themselves present no difficulties.  They will be turned from 50mm diameter steel rod.  And the axles will be all identical.

But, those supports are complex, and will need to be silver soldered parts, or possibly cast from 3D printed lost PLA bronze or brass.  Just drawing them was challenging.

This is a complex project, and the parts are complex.

Considering that the original cannon barrel was made in 1866, and the steel/iron chassis made approximately 20 years later (the original barrels were mounted in a wooden carriage),  the standard of the workmanship in the originals is simply superb.   Even at 1:10 scale, and using modern equipment including CNC machinery, I am struggling to match the standard of fitting steel pieces together so neatly.  I am in awe of the original engineers.

(and by the way.  Neil M, who very kindly loaned me the rivet gun which died, has loaned me a replacement gun.  The replacement gun is a bit bigger, and more fierce.  It requires more care in not overdoing the hammering, and bending the steel parts or producing “two-bobs” in the work piece.  “Two-bobs” will be understood only by older Aussies?  They are unintended dents in the workpiece produced by hammering.)

A Transom on a cannon. And a lost hearing aid.

 

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After a fruitless 3-4 hours searching for my lost hearing aid, I decided to make a bit of progress on the Armstrong cannon chassis.  At least I got the workshop floor swept clean for the first time since last winter.  The tigers should be hibernating in this cold weather.

In the above photo you can see that the rear cross member, which I have named the “transom”, is now bolted into place, with 14 M2 bolts and nuts.  Later these will be replaced with solid rivets.   I reckon that I had about a 70% success rate of inserting the tiny M2 nuts.  The other 30% are somewhere on my workshop floor… probably keeping the hearing aid company, wherever it is.

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When those connections were made, ensuring that the upper girder surfaces were parallel, I filed the angle brackets flush with the girder surfaces.  To ensure that the file did not scratch the girders, I rested the end of the file on a sheet of paper.

The next job is to make the front joining piece of the chassis.  It is a box construction, so will be more complicated, but should make the chassis  quite rigid.

It is a bummer having only one hearing aid.  About $2000 to replace the lost one.  I would have preferred to spend that sort of money on a tool.   Or a good drone.  But SWMBO is adamant.” get that hearing aid replaced!! ” (at least that is what I think that she said.)

 

Armstrong RML. A Little More Progress!

Only a half day in the workshop today.  Wednesday is my Model Engineering Society weekly “Zoom” meeting, and I would not miss that for quids.

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But, I did get into my workshop after that.  And this is what I made….

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I am trying to make a bracket to join the side girders of the Armstrong RML cannon to what I will name the “transom”.  The transom is the lump of steel joining the side girders at the back of the chassis.

“No big deal” you say?  Well, that bracket has angles of 90º, 4º, 6º,  and some indeterminate ones.   And must sit flat with 2 pieces.  And is a single piece of steel.

First I tried to bend a piece of 2mm steel.

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Even though the bender is rated only for 1mm, it managed 2mm thick plate.

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Plus some hammering in the vice…

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…but machining all of those angles and distances was just too difficult….   This steel effort was just not up to scratch.   Look at the gap under the bracket.  Yuck!

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I cut out some brass pieces, and used a vertical belt sander (the Radius Master), to get them to fit snugly…..

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then cut some separate pieces to complete the brackets and secure the transom…..

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checking the fit of the right angle piece…

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then silver soldered the pieces together.  The bits of steel are to keep the brass pieces in position during the soldering.

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That is the angle bracket being held to the transom by my rather dirty fingers.  But, it is all nice and tight, and will do the job. Rivet holes yet to be drilled.   Soldered joint? I hear you ask?  “As strong as the parent metal” I answer.   One made.   A bit of filing required.  And 3 more to go.  They will be painted the same colour as the girders eventually, so who will know that they are not steel.  Just you.  don’t tell, or else….

 

Armstrong RML Model cannon. Assembly -1

Not much happens in each workshop session.  I am still a bit unsure whether I should only post when some significant progress has occurred, or whether the minute daily progress is enough.  Whichever occurs depends on my mood.  At the moment I am posting daily progress.  If it is just too trivial and boring, well, hang in there.  No doubt there will be big significant gaps in the future.

Today I thought about how I would assemble the chassis for the Armstrong cannon.  And I decided to do some woodworking.

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So, I machined a block of wood, exactly the size to separate the chassis girders.

Wood has an advantage over aluminium or steel.  Apart from being cheap, it is slightly compressible.   Here, I have accurately machined a block of wood, and by adjusting the tension in the G-cramps, I can adjust the distance between the girders to exactly what I want.   And using the granite setup block to keep the upper girder surfaces exactly parallel.

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Getting those girder surfaces exactly parallel, on a granite setup block.

 

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Then I marked out one of the end pieces, filed out the girder flange recesses, and fitted it into place.

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The end piece will eventually be riveted into place, using an angle bracket.  The dented girder corner top right, occurred when I dropped the girder onto the workshop floor!  Or maybe it was a Russian shell hit.

So, not much to show for a 6 hour workshop session, but actually, some decisions made.  And more small steps.

And a BIG discovery!  Another  Internet search has shown some more of this exact cannon at Warnambool, Victoria.  And from the few photos on the net, those Warnambool cannons are more complete than the ones which I measured at Port Fairy!

Ah.  Fuck this virus.  I want to go to Warnambool.

 

 

91 x 4 drilled holes. Yes, counting.

Today I drilled the girders of the chassis under the Armstrong cannon.  Each girder has 91 rivet holes.  Later I will need to drill more for the gear shafts, and for the center pivot bar.

The holes are 2mm diameter.

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The mill drill setup. Re- indicating the vices again took me about 45″.

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Firstly all of the holes were center drilled, then drilled through.  The rivet confirmed a nice sliding fit.

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364 holes, through 5mm of steel done with one center drill, and one 2mm drill.  That is pretty impressive IMO.  More than 1.8 meters of steel with 2 drill bits.  And using my olive oil and kerosene lubricant-coolant.   And the bits still seem to be sharp.

Each girder took about 28″ to drill the 91 holes.   CNC of course.  It has been a while since I said it….. “I love CNC”.

 

Armstrong RML Chassis Girders

 

chassis R rear obl

 

Having made the decision to try to mill the girders from solid steel bar, I bought some 50x16mm bar and cut it into 400mm lengths.

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Then milled it to 46.4 x 14mm, then used carbide end mills to form the girder profile.  This process produced a large amount of hot, sharp chips, and took 2 full day sessions in the workshop.  Each evening I spent about 30 minutes pulling bits of swarf from the soles of my boots with pliers.

And I discovered the limits of my milling machine.  The 5hp spindle motor never hesitated.  Nor did the axis AC servos.  I did manage to chip the cutting edges of  a 12mm carbide end mill when it dropped onto the milling table.  And I blunted another one.  Not sure how that happened.  Maybe hit a hard bit in the steel.   No, the limit of the machine was the ability of holding the end mills in the ER40 collet chuck.  If I pushed the depth of cut or the feed rate too hard, the cutter would start to move in the chuck.  I managed to ruin one work piece in discovering that fact.

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There is virtually no distortion resulting from the milling.  The apparent bend in the photo is photographic distortion.

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The Vertex milling vices are within 0.02mm for height.  I picked up the second vice cheaply on Ebay a couple of years ago, with this exact purpose in mind. (milling longish workpieces)

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3 made.  One to go.  Plus the bottom 6º shape and the 4º ends.   Each 4.5mm deep pocket takes about 25 minutes, at 300mm/min feed rate, 1.5mm depth of cut, 2700 rpm.

I should be able to finish the girder shapes tomorrow.

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These milling marks are visible but very not finger tip palpable.  Any suggestions for a good method of improving the finish?

Then to mark out the rivet positions, and insert about 100 rivets into each girder.  In the model these will mostly be decorative.  In the original they held the components of the girder together.  Luckily for me, a fellow member of our model engineering society is a very experienced riveter, having worked in aircraft manufacturing, and he has offered to spend a session teaching me some basics.  In the original cannons, the rivets are superbly neat, regular, and obsessively carefully laid out.  I will try to do likewise.

Model Armstrong Cannon. Machining the trunnions-3.

On my “reject” barrel the silver soldering was problematic, and one trunnion was subsequently glued into place with Loctite 620.  This proved to be so effective, clean, and controllable that I used the Loctite for the main barrel.  The following video shows the Loctited trunnions being machined, and showing no signs of being dislodged.

It also shows a possibly dodgy but successful method of rounding the ends of the trunnions.

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The finished trunnions and shoulders.  Resting on a 3D printed platform which is quite handy.

Click on the arrow to see the 5″ video.

Armstrong RML Cannon Trunnions – 2

Silver soldering the trunnions into the barrel and the squared blocks did not go well.

For a start, I did not know the composition of the steel of the barrel.  The trunnions were/are silver steel, and the blocks were mild steel.  So it is possible that I did not use the best flux.

And the barrel is quite hefty, so I knew that it would require a lot of heat to get it to temperature, and to keep it at soldering temperature.  So I used a large oxy-propane torch, and heated it to dull red heat.

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The steel pieces fluxed and wired together, ready for heating

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It was a cool day, but the heat output from the red hot barrel was ferocious.

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Soldered, but one side was not good, and a hammer blow dislodged it.  Damn.

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The good side, partially machined.

I dithered about how to deal with the faulty side.  I was not enthusiastic about re-soldering it, expecting that the good side would fall apart.

So I cleaned up the pieces, and used high strength, high temperature, Loctite 620, to join the pieces.  The machining will test the strength of the joins, so I will give it the full 24 hours before testing it.  This is the “reject” barrel.

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Still pondering how to join the trunnions of the “good” barrel (front).  I will discuss it with my colleagues tomorrow when we have a Model Engineering Society meeting on “Zoom” video link.  The 3D printed barrel at back is a handy “how it should look” example.

 

 

 

Armstrong RML Cannon Trunnions 1.

cannon from above front

The 80lb Armstrong RML cannon trunnions were probably heat shrunk into the sides of the barrel.  (WRONG!  See post from July 2020.  The construction of these barrels was much more complex than I had imagined.  The trunnions were part of a forged ring which was heat shrunk then welded to the other components of the barrel).  The squared off barrel sides would have been part of the original wound and welded steel rods, and machined to shape before the trunnions were inserted.

The hole above the trunnion is to hold one of the 4 sights.

For the 1:10 model I considered various construction methods. This is what I decided…

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The 20mm diameter trunnion is fitted into a milled steel block, and the 2 pieces on each side are then silver soldered into prepared recesses in the barrel.

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The the barrel is mounted in the CNC rotary table and tailstock.  15mm deep holes are drilled into the barrel….

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and widened to 20mm diameter (drilled then milled)……  (for cutting fluid I use a mixture of olive oil and kerosene.  It produces a lot of evaporated fluid but is very effective at keeping the job cool).

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….then complete the recess.   The bottom of the recess is 8mm clear of the bore.

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Next step is to make the blocks, the trunnions, and silver solder them all together.  Not entirely authentic, but compromises are required when scaling down.   Still on the reject barrel, as a trial run.

Rifling the Model Armstrong RML

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The HSS cutter is mounted in a tight 3mm wide slot in 16mm silver steel.  The 4 mm cap screw pushes the cutter up by 0.2mm per full turn of the screw.

The following video shows an air cut of the rifling cutter in the CNC rotary table on the CNC mill table.   Then some actual cuts in a 1:10 scale cannon barrel.  This barrel was a reject, and was used to practice the rifling cuts.

You can click on the arrow in the box below, or see the video full screen in YouTube.

 

Laser Cutting High Speed Steel

As previously detailed, the rifling cutters which were made from a broken Brobo blade were unsuitable because I had not taken into account the thinning of the blade due to hollow grinding.

So I bought some high speed steel in the form of woodworking thicknesser blades, which were 3mm thick.  Also, I redesigned the cutters to be a bit more robust, and take a 4mm pin instead of the previous 3mm pin, which looked a bit spindly.

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6 cutters from one thicknesser blade 225mm long, 3mm thick

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3.03mm thick.  Just right.

 

NBN. At Last!

And about the last.  The fibre optic network was commenced about 3 years ago, and I applied for a connection shortly after.

Despite living in the centre of Victoria’s second biggest city, my house was not connected to the National Broadband Network until today.

Until then I have coped with download speeds as low as 1mb/sec, and uploads as slow as 60kb/sec.  Do you wonder why I upload so few videos?

Today, the NBN was finally connected.  The download speed is a blistering 50mb/sec, and uploads 25mb/sec.  Wow!

Just to celebrate, I am posting some pictures.  Not much to report from the workshop, but I am accumulating some items in readiness for rifling the model cannon bore.

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This photograph would typically have taken 60-120 seconds to upload previously.  Today it took about 5 seconds!    As you can see it is a cold saw blade which has seen better days.  My bad, unfortunately.   But I saved the pieces,  because these blades are made of high quality tool steel.  I have had some parts laser cut .

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The laser cutter left the tabs intact so the tiny parts would not be lost.

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The 2.5mm thick part popped out with a bit of finger pressure.  Not much tidying up required here, but I will sharpen the cutting edge.  This will be the cutter for the rifling of the model cannon.

This is the first time I have had parts laser cut, and I am impressed by the accuracy and smoothness of the cut and the narrow kerf (0.2mm).    Oh, and the cost.  It was surprisingly inexpensive.  ($AUD26).

 

Repairing Failed 3D Prints

As a beginner, I have a fair percentage of unsatisfactory prints.

Print breaks free of plate.

Supports fall over.

Overhanging areas insufficiently supported.

Holes appearing due to wrong settings.

etc. etc. etc.

Most of the time I just bin the failure, change the settings or setup, and make another print. And wait another 2, 9, 12 or 24 hours……  Not a huge financial cost, but does involve waiting.  And I am not very good at that.

I used to grow olives and make olive oil.

Sometimes the bottles of oil were sealed with wax.  Melting point 85ºc.

After a failed print of 6 items today, due to inadequate supports of overhanging areas, I wondered if the holes and thin areas could be fixed with the bottle sealing wax.  After all, lost PLA casting is just a descendant of the lost wax method in the metal casting process.

So I found the left over remnants of the bottle sealing wax, and heated up a soldering iron.

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One of the failed prints.  This is a wheel trolley bracket for the model Armstrong cannon.  The moth eaten area was overhanging, and the support had fallen over.  The area was thinned and the holes were not properly formed.   If a brass or bronze casting was made from this, it would have been unusable.

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The 850g slab of bottle sealing wax, and soldering iron.  I do not know if this supplier is still available.  It was not expensive.

The soldering iron is heated, dipped into the wax, and the molten wax carefully dripped onto the deficient area of the print, gradually building it up.

The wax can then be shaped with the soldering iron, or a heated knife, or even a finger or thumb.  I also tried a blade shaver and sharp knife.  I think that my soldering iron, and finger were the best tools.

 

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The repaired area.  It looks unsightly, but of course the wax will all disappear during the casting process, along with the PLA.

I am probably reinventing the wheel with this idea.  Again.  But have not seen it used anywhere else.  So there it is.  I think that it will be useful to me.

PS>. 12 hours later.  I now realise that this is so old hat that I am embarrassed that I posted this.  Reinventing the wheel,… that’s me.

 

 

Bronze Casting. 1.

My model Armstrong cannon has some components which will be difficult to machine, and would involve silver soldering many tiny pieces.

For example, the steel brackets in which the wheels are supported, and the centre column.

rear trolley

There are 4 trolleys like this.  Each one has 2 or 3  wheels.  It is a Z shaped profile with 3 gussets visible and 2 more inside.

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The centre column.  It could be fabricated.  

But being basically lazy and always looking for the easy way out, I have decided to investigate the possibility of casting these parts.  And some others.

So I have printed them in PLA filament, with a view to a “lost wax” type of casting process.  It will be “lost PLA” of course.  Maybe doing the casting myself.  But also checking the possibility of having it done professionally.

The PLA printed parts which will be melted and burned away in the casting process, have to be as well finished as possible.  So I have been experimenting with various settings in 3D printing.  One problem is that the molten plastic thread has to be supported.  Overhangs up to 45º or even 60º can self support.  And even horizontal overhangs can self support if the gap is not too big.

print unsupported threads

But this gap, about 20mm, proved to be too big…

print unsup oblique

The threads are partly bridging the gap…

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Horrible.  It is the underside, but even out of sight, it is unusable.

So, I am printing up some supported versions, even as I type this.  And I am going to look at some casting equipment which I might be able to borrow.  Apparently the gas furnace is very noisy, and it needs a home with no close neighbours.   List…. a furnace capable of melting bronze, a crucible, investment casting powder,  protective gloves, helmet or face mask, leather apron, tongs, slag ladle, a casting box.   There are many YouTube videos on the subject of lost PLA casting.    Watch this space.  But if the quote for professional casting from my printed molds is not too fierce, I will probably take that path.

Model Cannon Barrel. (T)rifling Thoughts.

My aim (as it were) in making this model cannon is to have a high visual quality exhibition piece.

It is a 1:10 scale model, 1866 Armstrong 80lb, rifled muzzle loader, blackpowder cannon.

One question which always arises is whether it will be actually fired.  My answer is that if it could be fired legally, it would be nice so I could make a video.  However, Australia has very strict gun control laws, (with which I totally agree), and I do not intend to flout those laws.  So this gun will not be capable of being fired.  It will have no touch hole.

To satisfy the visual appearance of a touch hole there will be a laser printed dot at the location.  Along with laser engraved Queen Victoria insignia, sight lines, etc.

But, it IS a rifled cannon, so I do intend to rifle the barrel.  And that needs to accomplished before the trunnions are fitted, and after the cascabel is fitted, so the orientation of the rifling is as per the original.

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The original rifling.  The 3 grooves are each 30mm wide, (clockwise or anticlockwise, not sure) and extend up to the edge of the powder chamber.  They are about 2 mm deep.  The powder chamber is slightly wider than the barrel bore, being continuous with the depth of the rifling grooves.  It is academic, because it will not be visible, but I will make it (the powder chamber, and the whole model) as accurately as I can, for my own satisfaction.  Fortunately the powder chamber is accessible to machining from the breech end, because the cascabel is screwed into position, and is removable.

Yesterday I started making the cascabel.  It was difficult.  The steel thread is lathe cut first, then the shape is lathe CNC’d.  Then there is milling the insides, and making a removable pinned rope retainer.  The third attempt was the most successful, but I am still not satisfied, and so there will be another one made today.   This is what I have so far…

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The turned barrel, threaded to accept the cascabel.  More work is required on the cascabel.

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The cascabel is mounted in an ER40 chuck.  It has been drilled and milled, and a removable insert is temporarily glued into place pending more machining.

 

Rifling.  Searching YouTube reveals multiple tools and setups from US sites.  Here are a few screen shots to show you some varieties.

From the sublime ….

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to the other extreme…

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No.  I will not be using a PVC pipe lash up.

The amateur designed and built machines are interesting….

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Sine bar on the right.

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Then there is the method of pressing a button cutter through the bore.  My bore is an odd size, so if I used this method I would need to make my own cutter.

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This one is a computer animation of a 19th century rifling machine, now a museum exhibit.   Can you see the barrel?   Armstrong probably used a much larger version of this type to rifle his cannons.

 

But I think that I will use none of these methods.  I have a CNC mill and a CNC rotary table.  Mach3 can control both of these machines simultaneously.   If I mount the cutter assembly in the rotary table, and the cannon barrel to the mill quill, I should be able to cut the rifling grooves.  Still working on this one.

Another Model Cannon Builder

One of my US readers has made a model rifled cannon, an Armstrong 110lb breech loader, 1:9 scale.  And it looks superb!  Best of all, he has made 2 videos of firing it.  I definitely recommend checking out the build and the firing in the link below.

I will substantially copy the rifling setup which Jeff used.  My sincere thanks to him for the information.   (ps.  although Jeff’s setup was tempting, eventually I used a CNC rotary table and CNC mill to do the rifling.  See later posts.)

http://jefenry.com/main/110PounderArmstrong.php

Armstrong RML. Roughing Out the Barrel

Today was humid.  But I hardly noticed.  I was attacking a piece of 72mm diameter steel rod for the Armstrong 80lb model cannon barrel.   Enough of the plastic printed shit.  Now for the real material..

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It was a piece of an axle.  No idea of the exact material.  But it is magnetic, turned beautifully.  So not stainless.

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The roughed blank, and the plastic printed model.

Next problem was to produce the 16mm bore, through 285mm.

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None of my 5/8″ (15.87mm) or 16mm drill bits were long enough, so I drilled from both ends.  Still have a substantial chunk in the middle.  The cutting fluid is my own mixture of olive oil and kerosene.   I used to grow and make olive oil and I have quite a bit left over.

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The roughed barrel, ready for CNC finishing.  And a 16mm drill bit which I turned down to a 10mm shank, and a piece of 5/8″ drill rod/silver steel drilled to 10mm, which I will silver solder to the drill bit to make it adequately long to drill through the whole barrel tomorrow.

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The roughed barrel, and the 16mm drill bit ready for silver soldering.  Yeah.  It is a bit longer than necessary.

Turning cannon barrels is really satisfying.  Still considering how to manage the rifling.

3D Printing a Cannon Barrel

There is quite a learning curve to 3D printing, and most of my prints so far have exhibited considerable room for improvement.  There are some helpful YouTube videos on the subject, but at my beginners level there is still a lot of trial and error.

I am still planning my next cannon model build, and printed some cannon barrels to improve my printing skills, and also to have a plastic model of the barrel to help decide about construction methods of the metal model.

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This is a 1:20 print, but was unsatisfactory because the cascable, and the rifling did not print.

The next prints took 22 hours (vertical orientation) and 24 hours (horizontal orientation) each.

Firstly the vertical orientation..

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It starts with a thin line which marks a little beyond the outside outline of the model to ensure that it is properly located on the printing plate.  Then a thin base to ensure adherence of the model to the printing plate, for the duration of the printing.  My plate is heated to 60ºc, which is not essential with the PLA filament which I am using.  I changed the filament colour for aesthetic reasons.

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Each layer of filament adds another 0.2mm of height.  The rectangular columns support the overhanging parts, and increase the overall support of the model during printing.

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The printing is finished after 22 hours.  I can already see some mistakes.  The barrel should be smoothly rounded, instead of faceted.

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After breaking off the supports.  Next to a bit of workshop rod  which I will use to make the actual cannon model.   Not quite long enough, but the rifled gun tube and cascabel will be made separately so the steel rod will be long enough for the rest of the cannon.

The next print was horizontal…

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I made the supports more densely placed to improve the support.  The cannon barrel is just appearing in the centre.

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I left the printer to continue overnight, and this is what I saw next morning.  Note the longitudinal placement of the plastic fibres.  Infill set at only 3%, which was adequate.  I increased the outside wall thickness to 5 layers, which was plenty thick enough.

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The finished horizontal print on its supports (front) and the vertical version (behind).   Apart from the facets, the appearance of the vertical version was better IMO.

Now I am ready to turn the barrel in steel.  I have obtained a facsimile book about naval artillery which was written in the late 19th century, it reveals that the Armstrong barrels were made in concentric pieces, and heat shrunk together.  I will adopt a similar method, making the cascabel and the central rifled tube separately from the breech sections.   Not decided whether to heat shrink them together, or silver solder, or Loctite. (ps. a week later.  Changed my mind.  Making the barrel from a single piece of steel)

The artillery book also answered my question about 64 -80 lb cannon and bore sizes.  When round shot was replaced by pointy cylindrical projectiles, the projectile weight could increase by increasing the length rather than the diameter of the projectile.  And some 64lb cannons were redesignated as 80 lb cannons, after modifications which did not necessarily alter the bore.  Unfortunately the book does not answer how the rifling was accomplished with a closed breech.

And I made another workshop tool.   This one is a lathe tool height gauge.

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I expect that the tough PLA will stand up to workshop treatment quite well.  It is light, very visible, will test upright and upside down tool bits, and will hang on a conveniently placed hook. Also, it is within 0.01mm of the required 38.05mm tool height.  A light rub of the base over fine emery paper will get the dimension right on.

 

 

3D Printing is FUN! (but still slow)

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My 3D printer.  Bought from Amazon on a special offer.  $AUD279.  Worked straight out of the box after minimal assembly, and using the supplied plastic filament (PLA).  You can see the large gear on the platten which I drew up using a CAD program.  I used the software (Cura) supplied by the printer manufacturer (Creality).   The printer is a Creality CR -10S.  The “S” refers to a “filament out” sensor which I have not yet installed.  I read some reviews of the printer before spending my money, and so far I am very happy with it.  You might notice some bracing bars which I bought separately on Ebay.  Not sure if they are necessary, but they might improve the print quality by reducing vibration in the printer.

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These gears and shafts were printed.  They were used to check the sizes of parts for my next model cannon build.  I used a program called “Gearotic” to plan the gear module, teeth numbers, distance between centres etc.  Gearotic is also great fun.

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The printed gear and pinion quadrant on a background of a photo of the real cannon.  On my model the gear and pinion will be made of steel or brass, machined from bar stock.

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Another part sitting on a photo of the original.  This demonstrated that I had got the corner chamfer a bit wrong.  Much better to discover the fault at this stage! 

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A half size print of the barrel.  This was just for fun.  The final part will be ~300mm long, and will be machined from steel.  This print took almost 4 hours.

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A print of the centre column which the cannon chassis sits on and traverses around.  It is ~60mm tall.  It will be tricky to machine from solid bar.  Could be fabricated in pieces and silver soldered together, but I am considering using the printed part to make a mould and cast the part in brass or bronze……   The original cannon column has an 5-600mm extension into the concrete base which my model will not need.

So far all of these prints have been made from PLA filament, which I read is easy to use, tough, rather brittle, and has a low melting point.  It is also inexpensive (about $20-25 for 1 kg).  I am still on the supplied small roll which came with the printer.  Future prints will be in colour!

The weather is a bit cooler today, so I might get back into the workshop and make some metal swarf.

 

 

Armstrong RML

Some images of what I am planning to be my next model build.  As mentioned in a recent post, I photographed and took lots of measurements of this Rifled Muzzle Loader at Port Fairy, and have been searching the web for more information.  It is said to be an 80 pounder, but the bore (6.3″) is more consistent with a 64 pounder.  Can anyone shed any light on the discrepancy?

(note added 20/12/20…  I have now completed the model of this cannon.  See photo at end of this post.  To answer the question above, my reading indicates that the 6.3″ bore was used for both the 64lb AND 80lb cannons.  The 64/80lb refers to the weight of the projectile.  The Port Fairy cannon in the picture is indeed an 80 lb cannon.  The extra capacity of the projectile and the gunpowder charge was permitted by extra strength of the barrel provided by a more advanced construction method.)

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Yes, there will be some interesting machining challenges.

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Not looking forward to all of that riveting.  Considering options.

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Most of the photos were taken with a Panasonic Lumix camera, but some, like this one, were with my iphone, using an App named “My Measures” which accepts annotations and measurements.  The barrel “diameters” above are actually circumferences.  And the “19” is the plate thickness.

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The emblem on the barrel surface.  I am hoping to engrave this on the model, but there would be a lot of time cleaning up the image.

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A web search turned up this image, which will be easier to clean up for laser engraving on the model.

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And some basic diagrams of similar design

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The rifling grooves are 1″ wide.  3 of them.  How to make them?

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I asked about rifling grooves at a GSMEE meeting, and Rudi showed me how it is done.  He made these 2 rifling tools.   They are pushed through the bore to create the grooves.  The bottom tool was most succesful, because it has a pilot diameter.  But, the tools cannot be pulled backwards, so both ends of the bore must be open.  But what about the cascable end of the cannon.  It is not a breach loader.

Then the penny dropped…..I remembered seeing this diagram…

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The cascabel screws into the barrel.  That opening will allow me to broach the rifling.  I do not know how the rifling was made in 1866!  (does any reader have information on that point?)  Note also that these barrels were usually made with some concentric tubes of steel.  I expect that the model will be one piece of steel, with the trunnions silver soldered.

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And I have started drawing up the cannon, massaging the field measured dimensions (which were obtained with a builders’s tape measure)…

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And doing gear calculations for the gear train and rack.  Lots more detail to go into the drawing and plans.   And thinking about construction methods meanwhile.  Now who has a metal sintering 3D printer for loan?

See posts on this site throughout 2020 for construction of the model….

 

 

The completed model at 1:10 scale.

Model Ship’s Cannon

I spotted this model cannon at the Townsville Maritime Museum, Townsville, Queensland, Australia.  The barrel is cast and bored.  Nicely detailed, particularly the barrel decorations.  My understanding is that such exuberant decorations on the original cannons would have been very costly, and not used on naval ships.  But they were sometimes commissioned by pirates who were spending their ill gotten gains.

The staff very kindly allowed me to reposition it for the photographs, and I am very happy to give the museum a thumbs up for some most interesting displays.

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Turkish Bombard – the barrel mouth

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Except for a name plate I have finshed the bombard.  The floral design at 12, 4 and 8 is not as clear as I wished, and the Arabic script at 2, 6 and 10 is even worse.  But it is cut in wood, and it is a first effort at such work, and it is not easily seen in a model only 106mm 4.2″ diameter, so I am reasonably satisfied.

Also, this was always a prototype, in wood, and I have not totally dismissed the idea of making it in cast iron or brass.  In metal I am sure that the detail work would be a lot finer.

Turkish Bombard. The Barrel Script

Well, I bought a pair of NSK bearings for the Z axis of my CNC mill, and removed the old ones and inserted the new ones.  Cost $AUD 200.  Plus 2 or 3 half  days of  dirty heavy work.    And the problem persisted!!@!@

OK.  Time to get an expert opinion.  Here comes the cavalry.  Thank goodness for my expert friend Stuart T.

Very puzzling.  Even for Stuart.  There was some unwanted movement in the Z axis (about 2mm), despite being apparently properly installed.  Not a problem with the ballscrew or ballnut.  Even Stuart was puzzled.

“have you got any left over bits and pieces?  Is it all installed the way it was before?”

To cut the story short, we installed a thicker washer below the locknuts, and it seemed the problem was fixed.  Or was it?

Today I did another test run of the bombard mouth Arabic script.  Worked fine.  OK.  Time to finish the bombard.

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Here is the finished result, ready for painting.  I have used a 20 degree engraving carbide bit with a 0.2mm flat end.  There is some loss of fine detail but it is I think, adequate.  When it is painted, the filling putty above the pin screws (the white circles) will be invisible.  The engraving took a total of about 60 minutes, at 500mm/minute, 15,000 rpm.

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The setup.   A large angle plate clamped to the table.  The work clamped to the angle plate.

The translation of the Arabic script is “Help O God the Sultan Mehmet Khan son of Murad. The work of Munir Ali in the month of Rejeb. In the year 868.”

More Scale Stuff

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There is the 1464 Turkish bombard (black), 17 tons, 307kg granite ball;  the 1779 long naval gun off USS Constitution or HMS Victory 24lb balls; and a 32lb carronade.  All 1:10 scale.  Interesting to see them together on my kitchen table?

Model Ottoman Bombard – Painting

I would have preferred that the title of this blog was “Finishing the Ottoman Bombard”, but I am still waiting for the vectors of the barrel mouth decorations and Arabic (?) writing, and the touch hole.

But I have at least painted the bombard, and the pictures follow.  You will notice that I have not attempted to reproduce the bronze or copper colours of the orginal in Fort Nelson.  Partly because I doubted my ability to make painting such variegated patterns realistic, and partly because the cannon would not have looked like that in its heyday of 1464.  It would probably have been either black, like most SBML cannons (smooth bore muzzle loading), or possibly gaudy golds and reds and blues like other medieval items.  So I painted it black.  I like it.  If I get evidence that it should be more colourful I can change it later.

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First coat – Primer.  Hmmm… interesting colour.

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Next coat – matt black brushed on, to fill the hairline wood cracks.  Incidentally, the (dirty) parquetry floor is also made from the red gum house stumps from which the cannon is made.

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final two coats –  matt black, from a spray can. 

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So there it is, finished except for the barrel mouth engraving, and the touch hole.  Now what to do with it…   SWMBO says it might be useful as an umbrella stand.

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The breech.  25mm diameter explosion chamber.  1:10 scale

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The barrel, 63mm bore.

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Assembled.  The model is 520mm long.

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It does need some decoration

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Ottoman Bombard Photo to Vector

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This is the low res photo from Fort Nelson.  High res photo on its way.

In the meantime, I have contracted with a US firm to convert the picture to vectors.  More $US.  ($US50 to be exact).

I am not sure that this is going to work.  But I will report to you.

I do wonder what that the Arabic/Turkish writing means.  Does anyone know?  I am pretty sure  that it is not complimentary to Christians/Westerners/Non Muslims.  Maybe it is just an instruction not to look before the touch hole is touched.  Or “do not stand here”.

PS.  Note added 17 Oct 2016.    The translation is   “Help O God the Sultan Mehmet Khan son of Murad.  The work of Munir Ali in the month of Rejeb.  In the year 868.”

868 = 1464 ce.

 

TURKISH BOMBARD – the real thing

I have found this video to be particularly useful in my modelling of the Ottoman bombard. The subject of this video is the gun that the Turkish sultan gifted to Queen Victoria when the Brits and the Turks were allies.  It might be one of the guns which fired on the British fleet in 1807, when it (the gun) was 343 years old!

Notice the colour.  It is aged bronze.  I am thinking about how to reproduce that colour on my model.

 

Length of the assembled gun 5.2m (17′)

Bore 635mm

Breech weight 8942kg

Barrel weight 8128kg

Average weight of shot 307kg

the model is at a scale of 1:10.  photos soon.  being painted.

 

Modelling A Turkish Bombard- The Pins

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There are 16 pins at each end of each section of the cannon.

These were certainly used as leverage points, for very strong men with large levers to rotate the 8-9  tonne segments against each other to engage and tighten the screw.

I cannot see how the pins would have been cast with the breech and barrel.  For my model I decided to make separate pins and fit them into the gap between the big rings, then insert a grub screw through both rings and the pin.  The holes are then filled.

I wonder if a similar method was used in 1464.  I would love to have a close look at the original cannon to figure this out.  From the photographs, I can see no evidence of later insertion of pins, but neither can I see how it would have been done any other way.

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Drilling the holes for the grub screws

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In order to continue with red gum, I made my own pins.  This is the setup.  The blank is held approximately centre in a 4 jaw….

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…and the pins are turned, centre drilled, drilled, cut to length,  and tapped M4.  64 altogether.

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The M4 x 25mm grubscrew is screwed into the pin.  The wood join is super glued.  Also, I am attempting to patch the worst of the thread tearouts.

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Using a battery screwdriver to insert the grub screws.  The pins protrude above the ring surface for a reason..

 

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Sanding the pins flush with the rings.  Check the photo of the original 1464 model.  There is also some wood filler in other splits.  Not surprising after holding up a house for 70 years.

The holes are now filled with wood filler, and will be sanded flush.  They should be invisible after painting.

Next the painting, the stands, and some cannon balls.  How to reproduce that aged copper colour…

 

Modelling a Turkish Bombard -4 Decoration

The decoration around the barrel is formed by a repeating pattern, which when milled, very cleverly forms 2 identical patterns.  One is excavated and one is the original barrel surface.  You will see what I mean if you look at the pictures in the earlier blog, and the video below.

It took me an evening of experimenting on the computer to work out the system and draw it.

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Then I measured the diameters of the 2 gun components, calculated the circumference, (OK it is not rocket science.   3.142 times diameter), then working out the number of identical shapes which would fit around the 2 different diameters, at the same size and spacing.   Amazingly, it took 18 shapes to fit almost exactly around the barrel, and 16 of identical size almost exactly around the breech.  the angular spacing was 20 degrees and 22.5 degrees.

Then the shape was imported into V-Carve Pro, and G codes were generated.

My CNC mill does not have a 4th axis, so I used a dividing head to move the workpiece at the precise angles.  See the setup in the video.  That meant that the pattern was engraved into 16 and 18 flat surfaces, rather than a continuous cylinder as on the original.

It worked very well.  There were minor compromises due to the shapes being milled with a fine end mill but when you look at the pics I hope that you will agree that it is effective.

I calculated that the milling had to be at a maximum depth of 2mm in order to cope with the curvature, but if I do it again,  I would reduce the depth by 25%.

The first part of the video is a shot of CNC drilling.  Then the CNC routing of the repeating patterns.  Each angular setting of the pattern took 4 minutes to complete.  136 minutes altogether.  In reality, it took a whole day, most of which was spent doing the setups.

 

 

Bombard Model. Turning the Breech

 

So if you watched the video, you can see that I have a problem with the big thread between the breech and the barrel, at least in the wooden prototype.  It might work better in brass or gunmetal.

The thread has a pitch of 6mm and a diameter of 60mm.   It is big.

My plan at this time, is to make a brass male threaded section, and glue or screw it into the breech.  Then to make a steel tap using the same G code, and cut a thread into the wood of the barrel.  (p.s.  note 30 Sep…  I continued to experiment with feeds, speeds, and cutter shapes in the wood.  The final result was OK so I did not make  metal threads.  That will have to wait until I do this project entirely in gunmetal or brass…  maybe never)

Turkish Bombard 1:10 scale

Just for fun I will use my newly converted CNC lathe to make a 1:10 bombard.  The original was cast in 1464 and was thought to be a close copy of the bombards which Mehmet 2 (“the conqueror”) used to breach the walls of Constantinople in 1453.  There are several of these bombards still in existence, including one in UK, which was given to Queen Victoria by the then Turkish Sultan.

These bombards were last used, against the British, in 1807, when a British warship was holed with substantial loss of life.  Pretty amazing for a 340 year old weapon.

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5.2 meters long, 1.060 meter diameter. 16.8 tonnes.

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The large thread connected the halves.  Easier transportation, and casting.

 

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Is this Turkish or Arabic?

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Granite balls are 630mm diameter.

 

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A reconstruction of the walls of Constantinople, with moat.  Almost 1000 years old in 1453  

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And as they are today.  Massive.  High.

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Huge siege cannon used in the final assault and fall of Constantinople in 1453. Diorama in Askeri Museum, Istanbul, Turkey.  The bombards were probably dug in, to manage the massive recoil, and concentrate the aim at a particular wall section.  There is a wooden structure built around the cannon in the background of this modern picture.  As far as I know there are no surviving  wooden structures like this.  Nor have I come across any old pictures, but if anyone knows of any I would be very interested.  The bombards took about 3 hours to cool, cleanout and reload.  

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My model will be about 520mm long.  I would like to make it from bronze, or gunmetal as in the original.  Any mistakes will be costly.

So I have decided to make a prototype in wood.  That will test my drawing, the machining procedure, and the final appearance.  Not to mention how the CNC lathe will handle the task.

I will use a very dense, tight grained Australian hardwood (red gum).  The wood was salvaged when my house stumps were replaced with concrete.  Some was used to make parquetry, and the rest was put aside for possible future use.  Such as this.

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About to cut off the below ground section of a 70 year old house stump.

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A 5hp metal lathe with a tungsten bit chomps through the hard dry wood.

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I turned 6 lengths before I found 2 that were satisfactory.  The rest had sap holes or splits.

I have used Ezilathe to generate the G codes.

to be continued….

 

CARRONADE 1

It has been a while since I posted, but I have been busy.

Some of that has been in the workshop making a scale model carronade.

A carronade, in case you are wondering, was a muzzle loading cannon, made 1776-1852 in the Scottish town of Carron, by the Carron company.  And subsequently much copied elsewhere.

It is a cannon which is short, squat and ugly.

Weighs about 1/3 as much as an equivalent bore long gun, (see previous posts), requires only 3 men to operate (compared to 9-11 for a long gun), and can fire balls or other nasties at 3 times the rate as long guns.

2 carronades, 68 pounders,  were on the foredeck of Nelson’s “Victory”, and they caused huge damage  at Trafalgar.   Can you imagine loading a 68 pound cannon ball into the muzzle of a hot cannon?   Many actions proved the killing power of carronades, and the British Admiralty were so impressed that they replaced long guns with carronades on many of their ships.

The French, and Americans were less rapid to  access this new technology, although Napoleon, who was an artillery officer, was adamant that the French navy should have the carronades installed as quickly as possible.

The British equipped some of their ships almost exclusively with carronades, and at close quarters they were devastating and they won some notable victories.

Unfortunately, although they were devastating at close quarters, they did not have the accuracy or range of long guns beyond about 500 meters.

So in the war between the Brits and the Yanks in 1812, the Americans found that all they had to do to win at sea and on the Great Lakes, was for their frigates to remain beyond the carronade range, and shoot their long guns, with many victories, and great frustration of the Brits, who were not used to losing naval battles.

Carronades were commonly installed on merchant ships, privateers, pirate ships, and small naval vessels, due to their relatively light weight, and small gun crew. But the Royal Navy stopped using them from 1852, when breech loaders were the latest new technology being installed wherever possible.

I decided to make another 1:10 scale model cannon.  A 32 pounder carronade, the same scale as the previously blogged 24 pounder long gun, to put them side by side for comparison.

It is almost finished.  I will post some photos soon.  Look forward to squat and ugly.

 

 

Video of Making the Model Naval Cannon

Click on the arrow in the screen link below to connect to the YouTube video of the making of the 1779 model cannon.  Probably of interest only to machine aficionados, but it does feature some very pleasant music composed and played by Lis Viggers.

The labels appear too briefly, so use the pause button to read them.

The segment on boring the barrel is really boring. (really)

And a few editing errors appeared.  I typed cascobels when it should have read astragals.  Not prepared to delete, re-edit and re-upload given my very slow Internet connection.

 

And this is a link to another YouTube video with an excellent description of how these type of cannons were made originally.  Definitely worth watching.

Cannon Trunnions

I am unsure whether the trunnions are the semi circular holes in the carriage, or the cylindrical bits of the metal barrel which support the barrel.   I am going to assume that the trunnions are the part of the barrel.  (I checked.  The trunnions are the cylindrical parts of the barrel which support the barrel.)

So, today I made some trunnions and silver soldered them to the barrel.  In the full size original version they would have been part of the barrel casting.

But before that, I polished the barrel with a Scotchbrite type pad, impregnated with some polishing compound.  And it made the barrel sparkle!

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Then I attached the knob at the breech end, M4 threaded rod attachment.

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Looks OK, Yes?  This protrusion would also have been part of the cannon casting.  It was used to attach the huge ropes which limited the recoil movement when the cannon was fired.  

 

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Turned some brass for the trunnion.  It was later cut into two pieces.

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Drilled the holes with an endmill in the barrel for the trunnions.  Stopped short of the bore by 3mm.  Jerry Howell specified threaded trunnions, but I decided to silver solder them in place.

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This is my silver soldering forge, for this project. (actually a hearth).   The barrel is still a hefty lump of brass, and I predicted that a lot of heat would be required to raise it to a suitable temperature.  The base is steel, and the bricks are fire bricks.  I used oxyacetylene as my heat source.

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After the silver soldering.  Not quite so pretty now.  I waited an hour before I could handle the hot item.  Note that the spigot in the bore which was Loctited in place, has come out.  Eventually, I became impatient, and applied wet rags to speed up the cooling process.

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Then a soak in dilute sulphuric acid for 15-30 minutes, to remove the flux.

Turning a cannon barrel

Today the exterior surface of the model 1779 naval cannon barrel was turned.

The piece of brass material weighed 5.1kg, was 300mm long and 50.8mm diameter.

I had used Loctite to glue a spigott in the bore, to provide a center and a driving diameter which the small CNC lathe would accept.

Although the lathe was nominally 300m between centres, the toolpost would move only about 200mm.  So the turning had to be accomplished by turning the cannon mouth end first, and then reversing the workpiece to turn the breech end.

The CNC lathe, owned by Bob Julian,  is about 30 years old, and it came out of a school.  In the course of this  job, it seemed to progressively free up, making us suspect that this is possibly the first time it has ever been seriously used.

The lathe electronics had been replaced by Stuart Tankard to use Mach3.  The G codes were generated by Stuart’s program “Ezilathe”, which is available as a free download on “CNC Zone”.   It is an excellent CNC lathe program, and I thoroughly recommend it.

I will eventually post some videos of the turning progress, but my Oz internet connection is so slow, that for the moment I will post photos only.

I started by turning a piece of rubbishy pine as a test.

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That’s me, watching carefully.  Later we installed the swarf cover.

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The metal turning lathe does not miss a beat chomping through wood.  These are the roughing cuts.  F300mm/min, S800/min.

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The Mach3 picture of progress.

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The finished distal half of the cannon barrel in pine.  If I stuff up the brass version at least I can have a wooden barrel. 

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Roughing the barrel in brass.  1mm cuts, feed 100mm/min.  It took almost 50 minutes for this section, and about 15 minutes for the breech section.

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The barrel mouth.  No gouging resulting from the 22 degree HSS cutter.

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Finish was quite good.  Will require minimal polishing with ScotchBrite.

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The workpiece was reversed in the lathe, the Z zero carefully set, the X unchanged, and the breech end turned.

The starting weight was 5.1kg.  The end weight, including the spigott was 2.9kg.  So at least 2kg of brass swarf, most of which I swept up and saved for possible future use.

Next to machine the trunions and some silver soldering.

 

1779 Cannon Bling

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Rings for attachment of ropes & pulleys, nuts and bolts, wheel pins and ferules, all made of brass in my workshop.  Note the square nuts.  Since this is a scale model, the originals would have been 50 x 50mm(2″x2″).

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The round bits are flat head bolts which secure the rear axles.

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Making the rings.  2.4mm (3/32″) brass wire is annealed by heating red hot, then wound tightly around a 3mm bolt.  The resulting helix is slit to form individual rings.

 

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The rings are flattened and adjusted using heavy pliers, then silver soldered to the threaded rods.  The hole in the smallest ring is only 3mm diameter.

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I intend to allow the brass to tarnish and darken.  The bright new brass is, I think, a bit glitzy.