Today I turned the trunnions.
Next step will be to turn the barrel diameter down to about 0.06-0.07mm bigger than the internal diameters of these parts. I will try to take some photos of the heat shrinking process for the next post.
Today I turned the trunnions.
Next step will be to turn the barrel diameter down to about 0.06-0.07mm bigger than the internal diameters of these parts. I will try to take some photos of the heat shrinking process for the next post.
This project is progressing slowly. Other issues are taking time at present.
There are 3 major components on these cannons…. the traversing platform, the wooden carriage, and the iron barrel. And a number of smaller components… the compressor (the recoil suppressor), the elevating mechanism (Smith’s screw), the sights, and various rope eyes.
I usually have something in mind to work on when I enter my workshop, but sometimes I just proceed where the mood steers me. I have actually been working on all 3 of the major components, with most progress on the traversing platform, which explains why the posts have been rather fragmented. Most of the work so far has been woodworking, but recently I had an urge to do some metalworking. So I made a start on the barrel.
The first step was to buy and cut to length the 1020 steel shaft. Then the piece was mounted in the 4 jaw chuck, and dialled within 0.05mm at the chuck. The tailstock end was supported in the fixed steady, and also dialled in. I was not trying for perfection because it is a case of time and diminishing returns, and straightness of the bore and concentricity between the bore and the exterior of the barrel are the main concerns.
So, the next step was to drill the bore to 16mm, using the extended drill bit which I had fabricated for the previous cannon, after centre drilling. The resulting hole was 305mm long, appeared to be straight, and just a bit rough.
I wanted a final bore of 18mm diameter. I have an 18mm reamer, but only 120 mm long, so I made an extension rod to fit the Morse 3 driving tab. But first I had to drill the bore closer to 18mm. So I made a D bit from undersize 18mm drill rod.
And the traversing platform now has the metal surface strips screwed into position..
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.
These daily posts might be becoming a bit tedious but you need to realise that I write them for my own diarising purposes as well as entertaining yous.
First today, I deepened the countersinks on the carriage stops which I had installed yesterday, and filed the bracket surfaces until the carriage showed no signs of catching on high spots. Then reassembled all of the bits in the vicinity.
I had machined some hardwood (Australian Mountain Ash, a close grained, hard, stable, pale hardwood) for the side steps, and today I made the brackets to support the side steps.
But, when I examined the steps today, I decided to remake the side steps, using the dark red hardwood Jarrah, the same as the rear platform.
The steel brackets were cut from 50mmx25mmx1.5mm rectangular section tube.
So, I think that those are the final parts to be made for this model. Now I need to decide about finishing the wooden surfaces. At this stage I am thinking of a dark wood stain, then a satin finish with a wood oil.
Firstly some woodworking to make the platform floor. Basic machining, drilling and screwing.
Quite pleasant to do some basic cutting on the bandsaw and thicknessing on the mill. HSS metal mills give a good finish on hardwood. It was finished quickly, and went so well that I proceeded to a task which I had been putting off, because I knew that it would be very difficult.
I made the carriage recoil stops, and installed them.
The problem was that the platform had been previously assembled, including gluing of the joints. And I was not going to break those joints for anything.
The stop bracket is about 30mm x 6mm x 2mm, and the stop protrudes about 5mm further. So the first question was how to make the rebate. The distance between the slides is only 53mm. Not much space to use chisels. And end mills could not be used. The metal surface of the slides is glued and screwed to the slides, so removing those was not an option either. I should have made the rebates BEFORE I glued up the platform. Oh well….
This is the setup which I used….
Then, rather than squaring up the recess, I rounded the hidden corner of the stop bracket. Easy!
Drilled the holes in the stop brackets for the screws, fitted the stops into position. Now, how to drill the holes in the wooden slides for the screws? The holes in the wood were only 1.4mm diameter. And a 1.4mm drill bit is not long enough for the drill chuck to miss the other slide. To avoid the other slide the hole would be excessively angled.
So I used another trick which I have used previously. I silver soldered the drill bit into some fine (2mm OD) copper pipe….
I will enlarge the countersink on the stops to bury the screws deeper, then file the screws flush with the stop surface. I doubt that the bit of angulation will ever be noticed. I used steel screws, because a brass one snapped off and I had to drill through the remnants. The steel screws are slightly bigger than intended, but not excessively. I had removed the gunners platform to improve the access. The area will look tidier when fully reassembled.
I am very glad that particular task is all but finished!!
ps. I have called them “stops” but that is probably not the correct term. The recoil of the carriage is reduced by the 5º slope of the slides and the braking from the compressor. The “stops” (or whatever they are called) are the final impediment in limiting the recoil of the carriage and its barrel.
The carriage wheels are at the front of the carriage. They do not actually contact the slides unless the rear of the carriage is levered up a few millimetres, to assist with rolling the gun down to the firing position.
They are constructed of bronze.
On my model, the gap between the wheels and the slide would be about 0.3mm.
Today I attached the wheel brackets to the carriage cheeks (the sides of the carriage).
I had deliberately made them with a slightly large diameter, knowing that I would need to reduce the diameters after they had been fitted.
This is how I reduced the diameters…..
…on a belt sander, holding the oiled shaft in my fingers and using my thumbnail to hold the wheels in position. After a few seconds sanding, and being careful not to sand my fingers, I tried the wheels on the carriage, rolling it up and down the slide. That was repeated multiple times until the wheels were just clear of the metal slides.
The single axle will be replaced by more authentic appearing separate axles with dome heads and pins. The brackets will be let into rebates in the carriage cheeks, and tapered in their upper halves.
Another half day workshop session saw some more small parts made for the Smith’s Elevating Screw at ~1:10 scale. As close to 1:10 scale as possible, but I decided to make the parts about 20% bigger than the dimensions I scaled off the poor quality drawing, to fit with small drill bits and end mills in the tiny end of the range. The smallest end mill which I used was 1.5mm diameter!
CNC Drilling the gullets in the gear with a 1.6mm drill bit, after turning the OD of 15.9mm. I made 2 of these parts, just in case.
This is the gear after completing the gullets with the 1.5mm end mill. 3000rpm, 0.5mm depth of cut, 30mm/min feed rate. (metal working is not great for hand beauty)
One more session should see the Smith’s Elevating Screw completed.
The barrel trunnions sit in bronze bearings which are held in place with screws, and under the heads of the large carriage bolts shown above. Land based “garrison” guns, like the ones which I am currently modelling, often do not have trunnion caps, relying on the weight of the barrel and the slightly deeper bearings to keep the barrel in place during firing. Naval guns always had trunnion caps to avoid the “loose cannon” disaster on board warships.
The round pins under the flanges are actually rivets, placed with the intention of preventing splitting of the carriage wood in the trunnion region.
I had turned some bronze to size to fit the trunnions and the carriage cheek cut outs. Once before I had cut the entire trunnion bearing and its flanges from solid brass, but for this one I decided to cut the flanges from 1.6mm sheet, and silver solder them to the round section.
The first issue was how to cut off the unwanted top section.
I turned a mandrel from aluminium and pushed the bearing cylinders into place…
and marked the segment to be removed.
The cross definitely identifies the part to be removed.
and milled away the unwanted bits. The sacrificial aluminium mandrel prevents distortion from holding the thin cylinders in the milling vice.
checking that they will sit correctly….a rebate will be made in the carriage cheeks so the flanges sit flush with the cheek tops.
Then silver soldered the flanges using a mini oxy-propane torch. The soldering hearth is made of Hebel blocks, which are cut fairly flat and accurately. The back block is to prevent the light components from being blown out of position by the gas torch.
After some sanding on a flat surface, and a check of the parts on the trunnions to exclude distortion, all is looking good.
Next session I machined the rebates
And I have added some more eye bolts…
But there was a problem with the eye bolts in the platform…Nuts on the inside of the slides prevented full movements of the carriage. On the originals, these nuts were buried, with nothing protruding. So I had to cut some pockets on the insides of the slides. I had not anticipated this problem when I bolted and glued the platform, and I really did not want to break it apart to make the pockets.
So, to cut these pockets in this very tight space, I made a special tool. Fortunately there was a corresponding hole on the other slide.
So that is where this job has progressed to. Still to be made are the Smith’s elevating screw, the compressor, the sights, the quoin. And then the surface finish.
Feeling a bit inactive on a hot humid day.
Thought that you might be interested in some more photos relating to RML’s.
We are having a La Nina summer. Relatively cool and wet. Humid. But, it is summer, and week long spells of over 30 degree centigrade days are expected, even in a “cool” summer. Today it will be 33c with high humidity, and those are not factors consistent with a pleasant workshop experience. So I will stay home and plan ahead how to make several components for the model Armstrong 80pr cannon on the wooden carriage and slide.
One item is the elevating mechanism for the 4 ton barrel. Several readers have helped with information about the mechanism, which I now believe to be a “Smith Elevating Screw” which adjusts the level of a heavy hinged iron bar, on which sits a wooden wedge called a “quoin”. The breech of the barrel sits on the quoin. The quoin is the coarse adjusting component, the screw is the fine adjusting mechanism.
The bronze gears which I cast yesterday were cut off the tree with small bolt cutters, band saw and hack saw. Then a belt sander to reduce the daggy bits.
The faces needed to be flattened in the lathe, but how to hold the rather thin, delicate, irregular gears?
Soft jaws made of aluminium, and exactly machined to match the external diameter of gear teeth, so there are multiple contact points, and minimal chance of damaging the teeth. I made these soft jaws ages ago, for just this sort of job.
The soft jaws may be used multiple times, machined to shape each time. Very handy in this situation.
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.
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.
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.
It took a whole day making and fitting the top caps of the trunnion mounts from brass.
On the Armstrong 80 lb RML model cannon, the trunnions are secured to the carriage with steel brackets riveted to the carriage sides, and the trunnions rotate in a bronze bearing.
Tidied the parts with a file and belt sander.
The bronze bearing involved some basic lathe work.
I had a bit of milling excitement while cutting out the steel components. I was using a 6.35mm 4 flute carbide cutter, and when I started the program the machine plunged into the shape at extremely high speed. When I checked, the feed speed was 60 times higher than I had specified. Somehow, the units had changed from mm/minute, to mm/SECOND. Amazingly, the cut was close to perfect with no damage to the workpiece. But, alas, it wrecked the carbide cutter.
I had recently upgraded the CNC software (Vectric V-Carve Pro) from version 10 to 10.5. Maybe some of my settings in the program had been changed in the upgrade? I never use mm/second. That is a woodworking CNC router unit.
I needed 20 spacers, 2mm thick, 13mm OD, 5mm ID, to finish the carriage axles for the Armstrong model 80pounder RML.
I could have turned some 13mm OD, drilled a 5mm hole, and parted off the spacers in my lathe, but I know from experience, that the pieces never end up exactly the same thickness (in this case, 2mm thick).
So I decided to try a Banggood tool which has sat unused since I bought it many months ago.
So I cut off 25 disks, from a piece of waste brass, 2mm thick. The Banggood tool worked well, except that it need swarf picked out after almost every disk. But it was quick, reasonably accurate, and the central drill bit was 5mm, just what I wanted.
The Banggood tool worked pretty well. I will buy some more of these. They were quite inexpensive.
Today I polished the ends of the trunnions, being careful not to remove the lasered lines and markings. I used a 200grit sanding pad in a sponge backed sanding disk in my milling machine. Also worked very well. I removed about 0.1mm of steel, without destroying the markings.
How fascinating is that for a topic!
Well, I found it interesting. Maybe says something about me.
My 2 carriages have 20 wheels and 20 axles between them. Plus the 4 big ones under the chassis’. I had made the wheels. The axles required some planning and thought, after all, whatever I did was going to be repeated at least 20 times.
I decided on stainless steel for the axles, and brass for the end caps. The originals were steel, but they will be painted, so the appearance of the metal is irrelevant.
First steps were to cut up 20 pieces of 5mm stainless steel, 25mm long, and drill 5mm holes in 12.7mm brass rod, and part off 20 pieces 5mm wide. With a few spares.
The the brass end caps need to finish 4mm wide, so there was a machining allowance of only 0.5mm on each face. So the silver soldering of the 2 parts needed to be reasonably precise.
Not quite finished. M2 Holes to be drilled through the end caps, and threaded to the brackets. I will use the CNC toolpost milling attachment which I made in 2019. That might warrant a short video.
A short video. Well, a bit over 5 minutes…
In retrospect I could have done the entire shaping and drilling and milling of the brass end cap using the toolpost mill on the CNC lathe. Would have been a lot more efficient.
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…
…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 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.
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.
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.
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.
Geelong is not yet in total lockdown, and the weather was beautiful sunny and cool. And, the Flagstaff Hill Maritime Museum website indicated that it was again open! So I grabbed my camera, jumped in my car , and had a very pleasant 2.5 hour drive to Warrrrrnambool.
Out the front, I spotted this…
It is a 68 pounder, smooth bore muzzle loader, not an Armstrong, but VERY similar. But what excited me, was that it is on its ORIGINAL teak wood chassis. Original chassis’ like this are incredibly rare. The barrel date is 1861.
My Armstrong cannon would have been mounted on a wooden chassis like this. The wheels are almost identical to the Armstrong chassis wheels.
Then I entered the museum, and asked where the Armstrong cannons were. The very pleasant lass directed me to The Battery . The museum itself is really interesting, with wonderful relics from the tragically wrecked “Loch Ard” and superb ship models, sextants, octants, clocks, a fabulous Minton porcelain peacock raised from the Loch Ard. And heaps of other fascinating items.
But I was heading to the Armstrongs…
There are two of them. 80 pounders, identical to the one which I am modelling. And they have parts which are missing on the ones which I had originally measured and photographed. One item is the big wheel seen in the photo, which winds the cannon carriage on the sloped chassis, to its loading and firing positions. It is almost 3′ / 1 meter in diameter. The handles and rear platform are also in good shape.
And a comment about the black paint. The cannons on HMS Warrior, of similar vintage, were also painted black. So it is tempting to accept that as the original colour of the Warrrrnambool and Port Fairy Armstrongs. But look at the colour of this Armstrong (Singapore or Hong Kong, can’t remember).. the barrel is white, and the chassis a bluish grey.
and this one… Portland Victoria I think.
It seems that in hot climates, black was not universal, at least for the carriage and chassis. But I digress. Back to the Warrnambool Armstrong…
This was the other item which I really wanted to measure and photograph…
It is the brass, or bronze, (gunmetal, I discovered from one of my references) quadrant shaped protractor, which measures to a quarter of a degree, the elevation/depression of the barrel. It had been broken off, probably stolen, from the Port Fairy cannons.
I spent 3 hours crawling over and under the cannon.
The manager of the museum casually wandered past, and started up a conversation, and gave me permission to take a rubbing of the VR crest on the barrel. She seemed very interested in my project, and even suggested that I should join the cannon maintenance and firing volunteer group. Maybe, when the virus has gone…..
I took 90 photos, and multiple measurements. This time I had some calipers. A beautiful day. No whales seen, to my regret.
Sometimes, the chuck in your lathe is too big.
I needed to machine some of the aluminium castings which I had made for the cannon chassis. They were too high by 1-2mm. But, the flanges were delicate and thin walled, and although the ends were flat and roughly parallel, they were not actually parallel. I wanted to use my most rigid and precise lathe, which is the Colchester Master 2500. But the bore on the chuck was greater than the diameter of the part which I was turning.
So this is the setup. A chuck in a chuck.
So, I held the part in the 80mm 3 jaw, centre drilled it, and supported it in the 3 jaw and the tailstock. It worked well. No disasters.
p.s. You might notice some advertisements in my posts from now on. Unfortunately I am at my storage limit on my current WordPress plan, despite deleting virtually all embedded videos, and placing the main ones on YouTube. I am facing the prospect of either deleting old posts, or increasing my WordPress payment plan to a business plan, which is substantially more expensive. I have decided to see if monetising the site will cover the cost of upgrading to a business plan. I do hope that the ads will not be too intrusive. Let me know what you think.
The assembly of my Armstrong cannon is progressing more slowly than I anticipated. No excuses. Just lots of holes to drill in precise positions, parts to turn and mill. And my workshop sessions have become shorter in the winter cold. Not that I mind the cold. I just light my workshop wood fire to remove the chill.
Today I have been making the wheels for the chassis.
I thought that the wheels would be easy to make. Just a bit of basic turning to size and form turning for the track groove and decorative relief on the faces. But as usual, I used whatever material I had on hand in the size. In this case stainless steel. It looks great when turned, but does work harden quickly, causing tooling problems. Parting off, through 50mm of hardened stainless steel is not much fun. In the end I used the band saw for parting, then tidied up the ends on the lathe.
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….
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.
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.
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.
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.
This is the Queen Victoria emblem and motto on the original cannon at Port Fairy, Victoria.
And this is what is now lasered onto the model cannon..
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.
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.
The wheels on the carriage, not the chassis.
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…
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.
After 4 -6 weeks of making castings, and remaking them, and remaking them again, I have finally started drilling holes and bolting pieces together, in preparation for final riveting.
Using my new riveting gun, I inserted a lot more rivets on the “A” chassis…and I used a technique suggested by one of my readers…bearing in mind that my first riveting efforts marred the surface of the parent metal, and were generally rather irregular rather than neat.
And the technique was this….
Each rivet head is centered over the anvil, and the pneumatic gun is used with the snap on the other end. The tape stops the rivets from falling out, and also protects the parent metal from the snaps. I experienced virtually no parent metal bruising. And was VERY fast. A major improvement. Many thanks Timothy G!
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.
I am waiting for delivery of the 5 l vacuum chamber so I can commence casting parts for my 1:10 Armstrong cannon. So today, I spent some workshop time riveting the chassis of the 1:10 Armstrong 80lb muzzle loading rifled cannon model.
I am a total novice as far as solid riveting goes. The following photos will prove that fact.
I have marked the surface of the girder with the anvil and snap. Doesn’t look good, but I am hoping that it will be acceptable after painting.
And just to lighten this post, yesterday I had a visit from my grandchildren, 2/3 daughters, sons in law, and SWMBO at my workshop.
So I fired up the Fowler 3″ traction engine and gave the kids a demo of filling the boiler with water, lighting the furnace, a discussion about the nature of coal, and a ride.
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.
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.
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.
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.
Considering how to model these 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.)
The strength and resistance to twisting and other movements of the Armstrong cannon is in the chassis. Specifically the design and strength of the longitudinal girders, AND the box section structure at the front of the chassis.
The box section has been a challenge in the 1:10 model. Actually, it has been a bit of a nightmare.
It has taken me 3 full day sessions to work out how to construct this assembly, to make the parts, to join them together, then a lot of filing to make the assembly fit the girders.
And, of course, the parts are riveted together, and I am a total novice at riveting.
So this is the result. Not totally finished and assembled, but getting there.
Again, I left my camera at the workshop. These are photos which I took with my phone.
And after the riveting, I have spent almost a full day of gentle and progressive filing to make the box section fit the girders. It all fitted beforehand. But after riveting, nothing fitted. All of that hammering clearly changed some of the dimensions. But, despite all of my pessimism, it all eventually fitted.
Now, I have another chassis to make.
Do I repeat the method, or maybe try something more efficient. Like making a solid block of brass or steel, shape the exterior to dimensions, then hollow the interior? Still pondering that one.
Part of the equation is that the riveting gun died. Not sure what happened. Maybe a blown O-ring? The final few rivets in the above pictures were hammered. My hammering is definitely not as neat as the rivet gun. I do have a rivet gun on order, but they are estimating an arrival date of the END OF JUNE! I cannot wait until then. And the faulty gun is not mine so I feel diffident about pulling it apart and maybe repairing it, maybe really screwing it up.
The last time that I cursed the virus I lost 25% of my readers, so I will just think it.
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.
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.)
Sorry, no photos with this one. As I was leaving my workshop I realised that I was missing one of my hearing aids. It was dusk, raining, and I spent almost an hour searching for it, but no luck. Then I forgot to bring my camera. So no photos. Big cleanup of the workshop in daylight tomorrow.
A half day in the workshop today. Finished silver soldering the chassis angle brackets, then fitted them, and secured them to the girders with bolts. In order to make sure that the brackets are correctly located for the drilling, I glued them with Super Glue initially.
The first half of the day was spent on the computer, working on Queen Victoria’s Royal cypher which is on the top surface of the cannon barrel.
It appears to have been machined into the barrel. On my model it will be about 12.5 x 20mm. My friend Stuart has a fibre laser which was used to permanently mark guidelines into 2 steel grinder rests (featured in earlier posts), and I am hoping that it will work similarly to put the cypher onto my model Armstrong cannon barrel. Another option would be to V carve the emblem, using V Carve Pro. Whichever method is used, I needed a bitmap file of the emblem. I found several with a Google Images search, but they were very low resolution. I should have made a rubbing of the cypher when I was at the originals at Port Fairy.
The curve of the barrel must be negotiated during the lasering or V carving. Still considering options for that.
So, when the Covid restrictions are lifted, that will be one of the first visits. To Stuart and his laser. A practice run on some scrap pipe first.
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.
But, I did get into my workshop after that. And this is what I made….
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.
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.
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.
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.
6 hours in the workshop today. I am constantly surprised at how little progress appears per session. Also surprised at how quickly the time passes.
I had left the external dimensions of the cannon chassis girders rectangular, to facilitate holding the items, while doing as many machining processes as possible with the rectangular shape. But today I bit the bullet, and made the final girder shape.
The 4 girders are all looking good. Next to start making end pieces and brackets. I am still waiting for rivets to arrive, so the assembly will be bolted together initially.
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.
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”.
There are quite a few pieces of angle iron in the Armstrong cannon. In the original they measure 95x95mm, and are about 15-16mm thick. Also, there is a definite radius between the 90º faces. At my 1:10 scale, the material becomes 9.5mm x 9.5mm, and about 1.5mm thick.
After considering various options, which included using extruded aluminium, and bending some sheet mild steel, I decided on the following solution….
I bought some offcuts of RHS (rectangular section) with 1.5mm steel thickness, and used a bandsaw and milling machine to produce the required dimensions in steel.
Firstly, on the subject of metalworking lubricants, I have previously mentioned my homemade mixture of kerosene and olive oil. And here is my favourite lubricant…..posing with the not quite finished cannon chassis girders…..
For this model cannon I need quite a few sheet metal parts. At 1:10 scale the final metal thickness is 2mm and 2.5mm. Having had a good experience with laser cutting the HSS cutters for the rifling tool, I decided to send an electronic file to the laser cutting firm, and see how the parts turned out. I decided to not include the rivet holes, thinking that the final positions might not be completely predictable. If all goes well I will probably include all of the holes in future orders.
The accuracy and quality of the cuts seems excellent. All of the parts will require final fitting and drilling for rivets, shafts, etc. I was pleasantly surprised at the modest cost of these 30 parts.
So next I can start assembling the chassis. Lots of riveting. About 500 rivets per cannon. Another skill to be acquired. Fortunately for me, one of my model engineering club colleagues used to work in aircraft manufacturing, and he has spent a session teaching me the ins and outs of installing solid rivets. And loaned me a riveting gun suitable for the 2mm rivets which I have chosen. Thanks Neil!
And finally for this post, I drilled some holes in the muzzle of the barrel. Do you know why they are there?
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.
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.
I should be able to finish the girder shapes tomorrow.
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.
I will start by making the main girders. At 1:10 scale they will be 400mm long, 11mm wide and 46mm deep. Some fabrication will be required.
Many rivets required. I will need to improve my riveting skills. One issue to be decided. Do I use copper (easy) or steel rivets (authentic)?. Whichever, they will be eventually painted the same colour as the girders.
And another decision. Your opinions invited. 2 methods for fabricating the girders.
TIG weld the flanges top and bottom (right). Or, (left) join 2 pieces of angle iron, then TIG weld the bottom flange. I don’t like the top groove to be filled. I do not really want to paint the surface that the carriage wheels roll along.
It is a very long time since I did any TIGging, so maybe some practice runs first…
And another option comes to mind…. just to machine the shapes out of solid bar. I think that I will try TIG first.
Later…. just remembered. I don’t have any TIG gas. Easter. Bum. OK. Back to square one. Maybe I will try to mill the shape from bar…..
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.
Click on the arrow to see the 5″ video.
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.
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.
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…
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.
The the barrel is mounted in the CNC rotary table and tailstock. 15mm deep holes are drilled into the barrel….
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).
….then complete the recess. The bottom of the recess is 8mm clear of the bore.
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.
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.
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.
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.
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…
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 ….
to the other extreme…
The amateur designed and built machines are interesting….
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.
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.
Naval Gunnery. A Description. by Captain H. Garbett. R.N. 360 pages.
Was originally published in 1897, and is a book which has been considered by academicians and scholars as being of great significance and value to literature. As such, it has been reproduced by Alpha Editions in an inexpensive, facsimile, paper back edition.
I came across an article about rifled muzzle loading cannons which referenced the book, and led me to purchase it from the Book Depository for $AUD20.
It, the book, is fascinating. 1897 English, is beautiful to read, non ambiguous, and unusually, does not provoke the grammar Nazi in me.
And the book has answered my questions about cannon construction. Not completely, mind you. I still do not know how they managed blind rifling. But most of the first 78 pages are about muzzle loaders, particularly Armstrong muzzle loaders. With diagrams.
One question which was answered was about the “recoil tube” located below the barrel of the Port Fairy 80 lb RML’s. I wondered whether it was like a gas shock absorber. The book explains that these long cylinders had a piston, and were filled with “Rangoon Oil”, (look it up. It is in Wikipedia), and they were indeed designed to moderate the rate of recoil of the cannon.
Another fact about rifled cannons… the rifling causes the projectile to emerge from the cannon slightly to the left or the right of the cannon axis, depending on whether the rifling is clockwise or anti-clockwise.
The book has chapters on breech loaders, naval mountings, quick firing guns, magazines, shell rooms, loading arrangements, sights, powder, cordite, projectiles fuzes, battleship development (up to 1897), battleship organisation and manning.
360 pages, 12 plates (black and white), 113 text illustrations.
If you have an interest in pre-dreadnought naval guns, this book is highly recommended.
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.)
After 3D printing a plastic 1:10 barrel I decided to have a go at turning one in steel. I had a length of steel 70mm diameter and 290mm long, which was just too short to turn the entire barrel, so I decided to make one of the breech reduction rings separately, when I make the cascabel.
I did not know what the steel grade was, but it was off a machine so I thought that there would be a good chance that it would be reasonable quality.
The turning was initially fairly routine.
I experienced 2 problems with the CNC turning. The tapered chase of the barrel, and the rounded fillets came out really well, but the straight sections of the breech developed chatter marks. I was preparing to take a skim to remove the chatter marks when I bumped the manual CNC control, the cutter dug in, and I got a deep score in the breech. And broke the carbide cutter. I turned away the dig in, but it left the breech diameter 3.5mm undersize.
I have no more steel of that size, and it will be quite a while before I get an opportunity to buy some. So I persisted with the slightly undersized barrel. It will be 62mm diameter rather than the intended 65.5mm. I still have not decided whether to scrap it and start again. But if I can get some more suitable steel I will remake it. I might even use the undersized barrel to make a 64lb Armstrong RML, which had a smaller diameter breech than the 80lb RML which I am making. (note added 19 Jan 2021… The Armstrong 64pd and 80pd barrels had the SAME dimensions. The main difference was that the inner tube of the 64pd guns coiled iron, but in the 80pd guns was solid ended steel. “Naval Gunnery” Garbett pp52-53).
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..
Next problem was to produce the 16mm bore, through 285mm.
Turning cannon barrels is really satisfying. Still considering how to manage the rifling.
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.
The next prints took 22 hours (vertical orientation) and 24 hours (horizontal orientation) each.
Firstly the vertical orientation..
The next print was horizontal…
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.
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.
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.)
Then the penny dropped…..I remembered seeing this diagram…
See posts on this site throughout 2020 for construction of the model….
I am home after a short holiday at Port Fairy, Victoria. Port Fairy is on the “shipwreck coast” of Victoria, labelled for the number of ships which were wrecked in the 19th century. Dozens and dozens of them, including the tragic “Loch Ard”. Port Fairy was a sealing, whaling, fishing village in the 19th century, but now survives on tourism and dairy farming. It was also the site of horrendous massacres of aboriginals.
Port Fairy was part of the coastal defences against a possible Russian invasion in the late 19th century, when Britain was the enemy of Tsarist Russia. Not that any invasion eventuated, or probably even contemplated by the Russians. But no doubt they were pretty pissed off by the defeats in the Crimea, so an invasion of a weak but gold rich British colony was not not totally ridiculous.
So Port Fairy, and nearby Warnambool and Portland were fortified with decent shore based artillery. The coast is incredibly rugged, with few landing places.
Today I saw some of the fortifications. And my next project?….
It is a muzzle loading, rifled bore, 80lb, black powder cannon (RML). The associated machinery is in poor condition, but much of it is present, and its original form can be inferred. Most of the external brass and bronze fittings such as sights and gauges have been removed, probably stolen.
The barrel itself is in good condition. It is fired to entertain the tourists every Sunday at 1200, and on New Year Day at 1400. Just a blank charge of course, about 1/8th of the charge which would have been used to fire a projectile. I was fortunate enough to be present at the January 1 firing, and it was awesome! Very loud. A sharp “crack”, and gout of flame, and air shock wave. Very impressive. Rated as an 80lb cannon. Far from the biggest ever RML, but still awesome.
And our model engineering society has a connection with the gun. One of our GSMEE members used to prepare the demonstration charge, and conduct the weekly firing. He operated a stone quarry, and was qualified to handle black powder and other explosives. He tells a story of one firing which had a funny ending. Someone else had prepared the charge, inserted it ready for firing, which was done. Unfortunately he had neglected to remove the powder container, which was a “Milo” tin. A few minutes after the firing, a very irate cop demanded to know who had fired the gun. The Milo tin had landed on his patrol car which was about 100 meters away.
No (legal) charges were laid.
And another connection… my son in law grew up in Port Fairy, and has fond memories of the town.
So I have taken many photographs of the gun and its carriage and machinery, and many measurements using a builder’s tape measure. The overall length is 4 meters plus protruding barrel, and if I use the same scale as my previous 3 cannons, 1:10, it will be about 400-500mm long. At this time I am preparing some drawings. Thinking about materials. Possibly steel. With some bronze and brass for the fittings. But I will finish the Southworth vertical steam pump first.
Back home now, and watching the news about Australia’s climate change fires, politicians posturing, and the president who ordered a murder. Absolutely appalled. “We got him”. WTF.