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"
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.
And that, dear reader, is that. Goodbye, best wishes, and thank you.
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….
1. 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.
2. First task to cut out the top of the handle bracket. Piece of cake with CNC.
3. 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.
4. 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…
5. The copper wire was out of the scrap bin. 2.4mm diameter.
6. Then milled some brass rectangular section (6x4mm) and silver soldered the copper pieces to it.
7. Then cut the brass approximately to length.
8. Slit the brass to 2mm width on the mill.
9. Drilled the fastener holes and attached to the breech block with BA10 bolts and nuts.
10. And ended up with a breech block which can be levered out, and replaced into position reasonably accurately and consistently.
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.
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.
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!
I will clean up the blackened heat affected trunnion ring later. This was a very satisfying day in the workshop.
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…
1. 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.
3. 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.
4. Milling the outline, ramping down…..2500rpm, 150mm/min
5. …and I quickly added a spray-mister to provide lubrication, cooling and chip clearing from the deepening slot.
6. 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.
7. 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.
8. 2 of these made today. Tomorrow I will turn the trunnions from the squarish ends.
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.
2. 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.
3. A further final contour, then parting the plug from the bronze bar. I finished the parting by using a hacksaw.
4. 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.
5. The brass shaft and pilot were each 18mm diameter, and fitted neatly in the bore and breech screw.
6. 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.
7. 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.
8. 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)
9. 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.
So, the model engineering of the Armstrong 110pr breech loading cannon continues….
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….
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.
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.
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.
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.
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!)
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.
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.
…and weighed the 306mm piece…
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.
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.
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.
And the most recent Rifled Muzzle loader, the same 80pr Armstrong Barrel, on a Dwarf carriage, and wooden traversing platform.
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.
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.
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.