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: Armstrong 110pr

THE LAST POST

8 years, ~900 posts. 13gB storage full. WordPress offers the solutions of buying a business package at 3 times the price, or deleting old posts to free up some space. I have removed almost all of my videos, with considerable reluctance, to make space to finish the posts about the Armstrong 110pr model cannon construction. However I still get comments from posts posted when I was a newbie, so I am not prepared to delete any more of them.

Just a thankyou to you, my reader. Questions, comments and communications from you are the grist for the mill of blog posters, and I am no exception. I have really enjoyed the journey. Feeling a bit sad, but I will resume my private diary entries, instead of venting my thoughts on johnsmachines.com

I had said that I would move johnsmachines.com to another platform, but now I am not so sure. Some repairs to my house are my next priority, and that will be too boring to blog. At this time I am not moved to start another model, but down the track, who knows?

I had saved the last little bit of storage space for the final photos of the Armstrong 110pr model cannon. Photos of the finished model follow.

The wooden carriage and traversing platform were stained with Japan black, then several coats of spray lacquer. It will be rubbed with steel wool and wood oil to give it a silky smooth finish.
Focussing on the rear tangent sights. I might add some locking screws to the sight posts later, but then again, I might not.
About 10º of elevation, provided by removing the quoin, and resting the barrel on the Smith’s elevating screw via the bed. Note the iron binders on the ends of the wooden slides.
Top view. Queen Victoria’s cypher, the barrel weight (just over 4 tons), and the proving arrow. No touch hole on the model. This view also shows the asymmetric position of the sights, caused by canting the rear sights ~2º, and moving them 2mm to the left so they are equidistant from the bore at the nearest point.
Almost horizontal with the Smith’s screw and quoin elevating the barrel. I will add some ropes and pulleys later. The right gunners’ platform needs to be pushed down a bit to sit in its correct position.
From the front. The wheels only contact the slides when the rear is slightly levered up, to encourage moving the carriage from the recoil position back to the firing position. (not that this model can be fired. It has no touch hole). Also note the absence of trunnion caps, which was common in garrison guns.
The model foresights were deliberately blunted to avoid observer injury; and left trunnion markings. EOC for Elswick Ordnance Company, barrel number 212, and 1862 the year the barrel was manufactured. Copied from an original Armstrong 110pr.

And that, dear reader, is that. Goodbye, best wishes, and thank you.

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.

Making the Trunnion Ring for the Armstrong 110pr

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

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

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

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.

Armstrong 110pr Breech Loader-2

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

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

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

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

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

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

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

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

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

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

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

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

Model Armstrong 110pr RBL – Early Steps.

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

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

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

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

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

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

And another old drawing of the barrel details.

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

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

…and weighed the 306mm piece…

10+kg

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

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

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

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

Another Model Cannon?

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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