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.

3D printing a PLA chess set for alu/bronze casting

Each piece takes 2.5 – 4 hours to print at the high resolution which I require to produce a good finish. The printed pieces will be attached to a tree, then encased in jeweller’s casting medium inside a steel cylinder. When set, the cylinder is heated to 200-300ºc to melt and vaporise the PLA, producing a cavity in the casting medium, into which the molten metal will be poured. The mould is baked for about 6 hours to thoroughly dry and harden it before the metal is poured into it.

There are 16 pieces in each army of a chess set. So 64 hours of printing for each colour. Plus failures. So far, in about 5 days of printing, I have produced the whites. That has taken almost 1kg of PLA, one roll. PLA is not expensive. I paid about $AUD22 per roll, including postage. Lately prices have risen to around $AUD30 per roll.

These are examples of a print run failure. This run was almost completed after 24 hours, when for some reason it just stopped. It was overnight, possibly a short power outage. Another run failed due to poor plate adhesion, again near the end of a run. I solved that issue by turning up the temperature of the extruder to 220ºc and the temperature of first few layers of the platform to 70ºc.
An army of pawns. One spare.
Half ready for casting. Now printing the opposition (in black PLA, only because that is what I have on hand, plus it might be another photo opportunity.). Can’t wait to see these in aluminium and bronze.

Chess

I have been teaching my 5 year old grandsons to play chess. It started with checkers, but the little buggers are already beating me at that! So I have upped the ante and introduced chess.

Then I thought that a chess set might make a nice present. So I explored THINGIVERSE and found these Egyptian styled pieces. Free download. And I have been printing them. I intend to cast them in bronze and aluminium.

This obelisk is a castle.
Queen on the right, knights on the left. Printing in progress so the supports are yet to be removed. Behind are the bishops and the king.

The detail and quality of these Thingiverse STL’s is superb!

I am printing in 0.15mm layers, using PLA.

Quite excited about this project.

I have a brain

And there is the proof.

In December I experienced several days of feeling unbalanced, staggery. A bit like being tipsy, but no alcohol involved. It passed after 4 days, but I attended my GP in the New Year for a checkup, and mentioned the experience. He arranged the MRI (magnetic resonance imaging) of my brain. 2 weeks later I was wheeled into the MRI magnet, and after 30 minutes of mechanical clanking and banging, it was over. No big deal. I was sure that it would all be normal.

Somewhat to my surprise, the MRI was reported that I had experienced a small bleed in my brain, a stroke, a cerebrovascular accident. A disease of old age. (70). No residual effects this time. But might happen again. It seemed that I might get the answer to THE BIG QUESTION sooner than previously anticipated.

Must get that model cannon finished!

But there is more to this story….

I am not a radiologist. Not even a registered doctor since retirement. But I could not see a bleed on the pictures. Oh well. You have to trust the experts. And gynaecologists are not renowned for their expertise in neurological radiology.

Then, as recommended by my GP, I consulted a specialist neurologist, and had a very thorough neurological assessment. He could find nothing abnormal. An interesting part of the assessment was a cognitive test, apparently the same one that Donald Trump took, after which he announced that he was a genius. Apparently I passed. It was laughably simple.

Most interestingly the neurologist could not see the bleed on the films. So then the films were examined by another specialist radiologist, and he/she could NOT see the bleed.

So, either the diagnosis was debatable, or non existent. The original symptoms were too vague to be diagnostic.

It just demonstrates the old adage. If in doubt, get another opinion.

Apparently the MRI set most of the nucleii in my brain spinning. See the following YouTube video. Sabine Hossenfelder is a German physicist and a brilliant teacher. Worth checking out her other YouTube videos.

Since then I have had no recurrence of the original symptoms.

Operating Manual for 80pr RML Gun.

One of the Armstrong rifled muzzle loaders at Warrnambool

The manual/handbook is undated, but it was printed for the Warrnambool Battery, and lists the iron carriage and slide, so that dates it after 1875. Before that the slides were wooden.

The following is my precis of the interesting specifications. A full copy of the Handbook is available on request

The weights given are: barrel 80cwt, carriage 41cwt, slide 74 1/4 cwt. So, the total weight of the cannon = 195.25cwt = 9.92tonnes (9.76 UK tons). That is the only document which I have discovered which specifies the overall weight, it is interesting to me because it explains why my model weighs close to 10kg. 10kg is close to 1/1000th of the full size weight, which is what is predicted from the model 1 in 10 scale!

Other specifications include: calibre 6.3″; total length 9’6″; 3 rifling grooves with a twist of 1 in 35 calibres, vertical vent 6″ from end of bore.

The sights are located only on the right side, and the tangent site is angled at 2º to the left. (to compensate for the projectile deviation resulting from rifling).

The hydraulic buffer piston had 4 drilled holes. The diameter of the holes was determined by test firing. The cylinder was filled with SOAPY WATER, (not Rangoon oil, which other cannons used).

The slide is of iron, except for the top ‘T’s which are steel.

The brake band permits the carriage to run back, and tightens automatically after recoil to retain it. A hand brake lever controls running up. (? should be running down?).

Barrel elevations: 5º down, 30º elevation, 19º down for loading. (Oops. I had set 17º as the loading angle. Hope that is not a hanging offence)

Charges: Full 20lbs; reduced 16lbs 12lbs, saluting 8lbs.

Projectiles: Studless. With gas checks. (which is further evidence that the manual is post 1875). 80-86lbs,

Fuzes: Percussion or timed (15 seconds).

Penetration of wrought iron plates: At range 0 – 8.5″; range 1500yds – 6.75″; 3000yds -5″; 4500 yds 4.25″.

The manual then lists the procedures for the gun crews. I will summarise those in the next post.

Page 1 of the Handbook for 80pr RML GUN.

with grateful thanks to Marten Syme, historian, for sending me a copy of the handbook.

Setting Elevating Gears on the Armstrong 80pd RML Model

The elevating gear is a quadrant gear, and it is centered on the trunnion centre. This is how I set it up on the model Armstrong RML 80 pounder. There are probably other better ways of achieving the result, but this is how I did it .

The barrel is removed from the carriage, and a round bar sits on the trunnion caps. The round bar is 20mm diameter, the same as the trunnions. The quadrant gear sits in position, and external calipers measure the distance from the quadrant gear to the exterior of the bar. The position of the quadrant gear is determined by its passage through the front transom. The rear position is determined with the calipers at the same setting.
The calipers measure the identical distance, at the front transom. The quadrant gear must be in the correct position. It is Super glued into position after marking.
Then the bracket which joins the quadrant gear to the cannon barrel is roughly positioned X,Y and Z. When satisfactory, the position is marked.
It all lines up. Next the BA8 fastening bolts will be drilled and tapped.

This is the second 80pd Armstrong RML model which I am finishing, this time for myself. It should be straight forward, having done it all before, but it is like a new adventure. Ah the joys of memory loss. Everything is new.

Book Review. “….Royal Gun Factory….”

Actually, the full title of the book is “Treatise On the Construction and Manufacture of Ordnance in the British Service prepared in the Royal Gun Factory” by John Fletcher Owen. Originally published in 1878.

The book is available in electronic form, free of charge, at Google Books. It may be read electronically, or downloaded to your own computer. Owen, J. F. (2018). Treatise on the Construction and Manufacture of Ordnance in the British Service Prepared in the Royal Gun Factory. United States: Creative Media Partners, LLC.

But, I really prefer to read books with the feel of paper, turning real pages, leaving bookmarks, making annotations. So, I ordered a hard back copy of the book from Booktopia. It came yesterday. Cost was a bit less than $AUD50.

I received an email that my order was “being printed” and that it would be sent within 2 weeks. It did arrive about 2 weeks later, and I was surprised to see that it had been printed in Australia! The binding is neat, and the feel is substantial. 510 pages.

Having looked at the electronic version I knew that the book is full of detailed information about the design, manufacture, construction, testing, and use of British artillery of the 1870’s era. Readers of this blog will understand my interest in the subject. There are many, many diagrams, plans, tables. A real cornucopia of information for the cannon modeller, or gun nut.

Now, understand my disappointment when I opened the book at random, to read …. anything. And I blinked and squinted, and tried to make out the words…..

THE TEXT FONT IS TOO SMALL!

With my glasses on, in a good light, I can just make out the words, but it is a struggle, not pleasant at all. And, the margins are huge! 30mm on the right! In the photo you can see the original page edges. They could have made the printed page and font size substantially larger. The reproduction result is a bit fuzzy, not sharp, which compounds the problem.

Compare the electronic version with a page from the reproduced book.

Electronic Version:

Printed (reproduced) Version.

Look at the dimensions in the printed version. Not at all clear. The small size, and degradation due to the reproduction process makes this book less useful.

The 143 year old book is a real treasure trove, and the information and diagrams etc may be freely reproduced without fear of copyright infringement. The reproduced paper version from Booktopia is disappointing. With a little more care it could have been wonderful. As it is I would give it a 5/10. I have sent feedback to Booktopia.

Some random pages follow, just to show more examples of the contents.

So, love the original book, disappointed with the Booktopia reproduction version. End of whinge.

Where to Make a Cannon? R.G.F.

The Royal Gun Factory. Originally established by Henry VIII as an artillery testing range, became the Royal Gun Factory in 1671, and became the largest cannon producing factory in the world by the time of WW1. It is located next to the Thames, in the London suburb of Woolwich, 8 miles from the centre of London, but originally it was a separate village. At its peak, in WW1 it covered 1300 acres and employed 80,000 workers. It closed in 1967.

You can see why they didn’t want it near the centre of London.

Mainly I wanted to show you some interesting images from the era of black powder cannons.

The steam hammer, installed 1874, has a downward pressure of 1000 tons.
The component being forged is red hot, and held at the end of the weighted lever. No idea what the worker near the hammer is doing, but it would be hot work.
Man power and steam power (oops, my bad. This steam hammer was in James Naismith’s foundry in Manchester, 1832)
They also manufactured artillery shells (studded type shown here, so presumably 1865-1877), and small arms, naval and garrison cannons.
and the lathes were suitably sized. Sketched in WW1.

Sources:

https://en.wikipedia.org/wiki/Royal_Arsenal

http://oldbritishguns.com/the-royal-arsenal

A Useful Book. How to Make A Cannon.

(provided you have access to a VERY large factory, and a very skilled workforce.)

This 450 page book is available for free download at Google Books. It is so interesting, and useful to this model cannon maker that I have ordered a hard-back copy to be printed and sent to me. Not overly expensive at just under $AUD50 inc postage.

Everything that you could ever want to know about making cannons in 1879. And more.

For example, I have read descriptions of the Armstrong method of making cannons with iron bars, by forming red hot spiral coils, then pressure welding the coils into a solid mass. Then using a massive press to join the sections together. But how were the trunnions formed?

This drawing comes from the book. The 100-150 foot long strip of ductile iron emerges from the furnace at the back, and it is wound around the mandrel on the left, while red hot, to form part of the barrel shape.
The “coils”, while still red hot, are press welded together. A medium weight cannon like the Armstrong 80 pounder would typically have had 4-5 pieces, while a large one, such as the 100 ton 17.8″ bore monsters at Gibraltar and Malta would have up to 14 component parts. The trunnion ring was usually forged from a single lump of iron.
The piece which became the bore of the barrel was pressed into place while the outer coils were still red hot, and held in compression when they cooled. Strips of iron are strongest along their length, so the coil method of construction was substantially stronger, and allowed larger charges of gunpowder, heavier projectiles, lower flatter, more accurate trajectories. When steel became more available after the 1870’s, it became the metal of choice for the rifled bores.
The bore itself was then rough bored…
….and then fine bored, using the technique invented by Wilkinson ~1800. Interestingly, the cutters are steel, and the guides are lignum vitae.
Forging the trunnions from a solid lump of red hot iron, using a steam hammer. Alternatively the trunnions were forge welded into bored holes. I was happy to read that, having silver soldered the trunnions into holes on my models.
This is a schematic of a 64 pound Armstrong RML. The 80pdrs were almost identical, tests having shown that the 64 pd barrels built this way were capable of handling the larger charges and projectiles. Note 4 separate coils, plus trunnions, plus cascable, plus steel plug and copper washer at the breech end of the bore.
The tapered powder chamber was formed with a broaching head.
The biggest muzzle loader ever built? Depends how you measure it. Not the biggest bore, but probably the most powerful, longest range.
This is 20 years later. The Royal Gun Factory, Woolwich. No muzzle loaders in sight.

Motorising a Mill-Drill Table

No, I did not tidy up for the photograph.

I have had this round column mill-drill for quite a few years. The head and the table are both able to be raised and lowered with a rack and pinion operated with a handle. It is a heavy unit, and raising the head or table by hand has always been a struggle, so much so lately that I have been planning to motorise the movements.

There are a few YouTube videos on the subject, but none for my particular setup. And both the head, and the table with its XY table and milling vice, are very heavy. I decided to really gear down the mechanism so the motor could be compact and not overloaded. So that meant another worm and gear in the train. I ordered a 1:40 worm and gear, but meanwhile a friend offered me one from his junk box, which I happily accepted. (thanks Stuart.)

A powerful, reversible, compact motor at a reasonable price, and not requiring complex wiring, is not readily available. But, then I thought, how about trying a reversible electric drill, with speed control? I have a Metabo 750w drill, and I decided to try that. If it worked I could buy another one on Ebay for about $AUD250. As it turned out, it is so easy to attach and detach the drill, that I will probably not need to buy another one. (note added March 11. I bought a second hand Metabo drill on Ebay for $30! It is very second hand, and battered, but has forward and reverse, 2 speed gearbox, and variable speed regulated by trigger pressure. 600 watts. Works like a charm!)

The next decision was whether to attach the motor to the head or the table. My original plan was to attach it to the head, but on testing the power required to turn the handles manually, it was obvious that the table was easier to move, so I have positioned the head at its maximum height, and will probably never need to move it again. The new mechanism was installed on the table.

The following video summarises the assembly of the components, and a brief demo. Click on the arrow to view it (10 minutes duration), or go to YouTube to see it full screen. It was shot on my iphone held vertically.

300pd Blackpowder Cannons at Williamstown

The cannon construction techniques which were pioneered by William Armstrong in the 1860’s led to more powerful and more accurate weapons. The 6.3″/160mm bore cannons which were shown in yesterday’s post, (and modelled by me,) were rapidly followed by larger cannons. The larger cannons were required to counter the iron clad steam ships which were replacing wooden warships. The colony of Victoria purchased 9″ muzzle loading black powder cannons for the defence of Melbourne, and yesterday I visited Williamstown to see 4 of them.

The 9″ rifled bore cannons fired projectiles weighing 300lbs! Cannons of this size were described according to the bore diameter, in preference to the weight of the projectile.

A fort was constructed at Williamstown (Fort Gelibrand), and 2 of the cannons are located inside a military establishment, unfortunately not accessible to the public.

As seen from about 20 meters, through the fence. Muzzle loading 9″ monsters. The projectile seen is said to be stuck there.

I was sure that I had seen some photographs of similar guns at Williamstown which were accessible so I asked some locals, and was directed to the foreshore.

That is Melbourne CBD in the background.

These 9″ guns are rifled (6 grooves), made in 1867, and muzzle loading blackpowder. They are very similar to the 10″ guns which were mounted on the monitor HMVS Cerberus, but these are garrison mounts whereas the Cerberus guns were rotating naval mounts.

The 300lb projectiles were loaded using a gantry which was mounted on the end of the barrel. The gantry mounting point can be seen as the small holes in the side of the barrel.
The loading gantry can be seen in this old photograph of one of the 9″ Armstrongs when it was located at Fort Queenscliffe.
A feature of the 9″ cannons was the “Elswick” recoil control mechanism. These substantial strips of iron extended the length of the chassis, and shorter pieces of iron were hung from the carriage to provide friction control of the recoil. The degree of friction was controlled with levers which adjusted the spacing of the strips.

Unfortunately most of the elevation control mechanisms are missing. The small bracket top left was probably to hold the steel rod which was used to perforate the gun powder bag after it and the projectile were positioned.
6 rifling grooves. The projectiles 1867 to 1877 would have had studs to match the rifling. After 1877 the projectiles would have used copper gas checks to engage with the rifling. The inner and outer coil layers of the chase of the barrel can be seen if you look closely.
The 9″ guns were manufactured at the Elswick works, Newcastle, England. and the Royal Gun Factory Woolwich England. The gunmetal trunnion caps are original. If you look closely at the barrel surface you can make out the outlines of the strips of iron which formed the coils.

HMVS Cerberus is a topic for future posts. An excellent source of information is found at http://www.cerberus.com.au

Elsternwick Armstrong 80pd RML’s

There were only 25 Armstrong 80pd rifled muzzle loaders made, all in 1866. A special order by the Victorian colonial government to the Royal Gun Factory at Woolwich, England. Until today, I had seen and photographed 5 of them. 2 at Warrnambool, 1 at Portland, and 2 at Port Fairy. I believe that there are only 10 still in existence. Today I saw 2 more. These are in the Hopetoun Gardens, in Elsternwick, Melbourne. They are on wooden slides, and have wooden carriages. The wooden components have been repaired, extensively filled, and re-painted. Some parts are missing, including the quoins (the triangular elevating wedges).

The barrel exteriors are in good condition. The muzzles are blocked, so I could not see the bores.

Here are some photographs.

The lithograph on the left is of a 9″ Armstrong cannon. Centre is the battery at Queenscliffe before the present fort was built. On the right is the monitor Cerberus, with 10″ RML guns. Cerberus was scuttled as a breakwater at Half Moon Bay, Black Rock. Her guns were removed and placed nearby on the seabed, where, as far as I know, they remain.
The weight refers to the barrel weight and does not include the chassis or carriage. Fort Gelibrand is at Williamstown, where there was a battery for the defence of Melbourne, consisting of 9 substantial cannons. I also visited Williamstown, and photos of the much larger guns which are still there, will appear in a later post.
The Port Fairy 80pd cannons were almost certainly originally mounted on wooden carriages and slides like these, until upgraded ~1877.

These carriages and chassis’ appear to be substantially original.
Queen Victoria’s cypher on these guns is in good condition and exceptionally clear.

Hygrometers, Humidors, and a bit of model cannon stuff.

I like to think that I have very few vices outside the workshop, where there are quite a few.

But, one of the vices in which I indulge occasionally, is a good Cuban. And I make a point of indulging no more than 3 per week.

And, actually, that does add to the number of vices in my workshop, because that is where most of the Cubans (and Bolivians, and other central Americans) meet their destiny.

SWMBO does not encourage cigar smoking in the house for some reason, but I quite like the stale cigar smell in the workshop. Come to think of it, maybe that’s what is keeping the tigers outside.

To cut to the story, my son in law, James, gave me the Humidor pictured above, for Christmas. A great gift, which I greatly appreciated. Mind you, I have a sneaking suspicion that he might have had an ulterior motive, because James too enjoys an odd cigar, and he likes his cigars to be at the perfect humidity of 75% when he visits the workshop, “for a chat” or whatever.

The humidor box is very nicely made, with a Spanish Cedar internal lining. Made in Indonesia. It shuts perfectly tightly and just the size for about 50 coronas. And it has a hygrometer to measure the humidity.

But…… it comes with instructions to calibrate the hygrometer. WTF! If I buy a Mitutoyo gauge, I assume that the calibration is correct. What is this “calibration”. And then there were the instructions for calibration….

  1. place a tablespoon of salt in a plastic dish, and add JUST ENOUGH water to make it damp.
  2. Place the dish, and the hygrometer in a zip lock sealed bag and let them stand for 6 hours.
  3. After that time the hygrometer should read 75%

Well that all sounded Mickey Mouse to me, so I asked my fellow model engineers at our second last meeting.

As usual, in our group of 15-20 participants, one person clearly knew ALL ABOUT humidity measurements, because he had worked in the munitions experimentation industry.

Next meeting, he brought the following hygrometers……

An electronic, high accuracy instrument.
2 thermometers, one connected to a well, and one in the air. The well contains water, and the difference between the temperatures in the thermometers is read off a table, giving the humidity of the air.
And this hygrometer……. see next photo for the reverse……
…which uses human hairs which contract when exposed to moisture, moving the indicator needle. The hairs in this instrument need replacing. Frank was looking for volunteers, but no members had enough hair to spare.

But! Do you know which method the explosives experts used?

The salt dissolved in water method!

Apparently that method is accurate to less than +/- 0.5 %.

So that is what I did. And after the hours of waiting, when the humidor hygrometer should have read 75% it actually read 65%.

There was a screwdriver slot at the back, which enabled me to adjust the calibration on the hygrometer.

The figures in the columns refer to percentage humidity at different temperatures with different dissolved salts.

Apparently the explosives scientists carried a kit which contained a selection of the above salts, and they used them to calculate the humidity of the air before conducting their experiments.

NOT MANY MODEL CANNON POSTS LATELY!

But I have been working on finishing Armstrong RML number 2.

Not much to show but I have been working on the gears, brake, and chassis……

This photo shows the brake drum on the big gear, the lever cam, and the stainless steel band bent into position, and pinched ready for silver soldering. Easy to make, but difficult to get exactly right. Too loose and the actuating handle bottoms out. Too tight, and the gear wheel refuses to rotate in reverse. So I ended up making 2 steel bands. The flaps were silver soldered. Top right, and I also made a dog clutch support bracket. Not physically necessary IMO, but consistent with the original.

Battery Point, Port Fairy, Victoria, Australia.

I originally examined the Armstrong 80pd RML cannons at Port Fairy a year ago. Then spent 2020 making a 1:10 scale model. Now, I am completing a second model. Here is a photo of the current status of the 2nd model. And no. There will not be a third.

The components are almost all made, but I estimate that there are many hours required to finish and fit them.

But this post is about my recent 2021 holiday in Port Fairy.

I spent some hours checking and getting more measurements……….

Assisted by my very curious grand daughter “what are you doing Pop?”
Who then decided to take over.

My son in law brought his drone to Port Fairy. It is a Mavic 2 Pro with a Hasselbad camera. I was sooo jealous.

And here is his footage of Battery Point. If you look carefully you can see me, my daughter, and Steve controlling the drone. This was a day after the photos above were taken, and my grand daughter was not in the video. Click on the arrow to see the 2″ video.

My daughter was interviewing me again. Amazed at the details being so similar on the real thing compared to the model. My SIL says that the Port Fairy cannons are 10:1 scale examples of my models. Unfortunately the wind noise was too excessive to post her video.

A Session on the Ring Roller

My current project is finishing the second Armstrong 80pd RML model cannon. I expect that will keep me occupied for a couple of months. But I probably wont post the steps, because it will be very similar to the posts from last year.

Yesterday, my GSMEE friend Swen Pettig asked if he could use my ring roller. The following video is a 7 minute rambling chat while he was finishing the job.

I made the ring roller quite a few years ago. It is slow, but quite controllable, and does a nice job. The 1/2 hp motor is geared down, 1:40. I have rolled steel up to 100mm wide and 10mm thick.

As you will see, Swen is making a scale model approx 1:4, of the first internal combustion car by Karl Benz.

Here, he is rolling the wheel rims from 10×10 mild steel square section rod 1.5m lengths. He made 2 front and 2 rear wheels. (needed only one front…. the car is a 3 wheeler).

Sorry about the absent chain guard. Just an oversight. I warned Swen about the possibility of inadvertent circumcision.

Old Photos of Armstrong RML’s

When visiting the Armstrong 80pd RML’s recently at Port Fairy, Portland and Warrnambool, I made sure to take photographs of any old photos which were on display. Some were very interesting.

Portland RML, not dated, but I would guess early 20th century, after decommissioning.
Portland RML, probably 1880’s
?1880’s
Information sign at Portland battery
Probably my favourite. The cannons of the Warrnambool Battery being relocated to Flagstaff Hill 1887. On wooden carriages, and towed by a steam traction engine.
The Warrnambool RML on its original wooden chassis & carriage. Adjusting the elevation with crowbars while using the sights. Traversing had been adjusted with the blocks and tackles.
Pulling the lanyard to fire. There was a recoil dampener. See next photograph.
At Flagstaff Hill Warrnambool there is an 80 pounder on its original teak carriage. I asked to see the recoil dampener which had been removed. 2 staff members very kindly took me into the warehouse where many unrestored items are located. This is the dampener. I guess that the bronze clamps were compressed onto a metal rod to reduce the recoil distance at firing.
Externally the 64 pounder was the same as the 80 pounder. On its original teak chassis.

Armstrong 80pr RML’s at Portland, Port Fairy and Warrnambool.

10 members of my family had a brief vacation in South West Victoria after Christmas. It was a nice holiday, but with three 5 year olds and an 8 year old, it was noisy.

I took the opportunity to revisit the Armstrong RML’s at Port Fairy and Warrnambool. And to visit the one at Portland for the first time.

Every time I see these cannons I learn something new about them. And I got to talk to a local historian at Port Fairy. Colonial Victoria purchased 25 or 26 of these muzzle loading rifled cannons in 1866. 10 of them are still in existence. I have now seen 5 of them. I believe that there are further barrels at Fort Queenscliff, Point Nepean, and possibly Cerberus which I have not yet seen.

“80pr” indicates that the cannons fired projectiles weighing 80 pounds. On all of these cannons the case of the elevating gears is stamped thus….

I am not sure what M2 GAR. stands for. Could it be an abbreviation of Mr WG Armstrong (later Lord Armstrong), the designer of these guns? (note 27 Jan 21. I spoke at length with Australian cannon expert Peter Webster. He said that GAR stands for “Garrison”. Not sure why, but maybe to distinguish it from naval guns.) R.M.L. will stand for “Rifled Muzzle Loader”. 80 PR will be 80 pound projectile. 6 FT PAR had me puzzled, but when I saw that the guns were designed to sit behind a 6 foot parapet I am pretty sure that will be the solution. And in a smaller font below, WD with a vertical arrow will indicate that the part has been approved by the War Department.

The Portland 80pr RML

From a distance, it looks good. The shapes in the carriage and chassis stand out with the white paint, and the assembly looks reasonably complete, except for absent winding handles and sights. Closer inspection however is disappointing. The cannon was restored in 1985 and the parts which were replaced such as the biggest gear, the elevation quadrant scale and trunnion caps, and elevation gear are significantly different from the originals on the Port Fairy and Warrnambool cannons. They appear to have been cut from mild steel in a fanciful representation of the original designs. Arc welding has been extensively used to join components. It is OK as a tourist attraction, but useless for historic study.

And instead of pointing over Portland Bay, it points at the large grain silo.

PORT FAIRY CANNONS REVISITED

Overdue for restoration works, the carriage wheels are largely crumbling into rust, and the girders have large rusted missing sections. The barrel of number 22 is elevated to a high angle which would never have been used, but is useful for firing blank charges for the entertainment of tourists, and which I enjoyed 12 months ago. Number 17 barrel rests on its parapet, at such a low angle that it too would never have used. The total lack of restoration does allow one aspect of the barrels to be visible, and that is the coil construction of the barrel segments.

Number 22
Close up of the breech steel. Pitted and rusted. Can you see the spiral strips of iron which were bent and hammered as red hot strips up to 200 feet long, around a mandrel?

I measured the widths of the strips, and found that those on the narrowest part of the barrel (the chase, near the muzzle) were the narrowest at 36mm, and those of the biggest barrel diameter, the breech, were 50mm wide.

As a comparison to the previous photo of a coil constructed barrel, this similarly rusted 1861 SBML (smooth bore muzzle loader) shows no evidence of the spiral iron strips, and would have been a cast iron construction with machine bored bore.

I was also able to work out the structure of the girders on the Armstrong RML, and the reason for all of those rivets. The top and bottom pieces are T section iron, and the sides are 3/8″ (9.5mm) plate iron. There are small pieces of iron to fill the gaps at the ends, and where intermediate rivets are used in the middle sections. Using a percussion technique, taught to all medical students for diagnosing pneumonia, I could work out the locations of all of the small middle pieces.

The girder end, showing the T pieces, side panels and middle filler piece.
My sketch of the construction of the girders.
Another family member being introduced to the Port Fairy RML cannon, probably as a fashion accessory.

WARRNAMBOOL ARMSTRONG RML’s

These have been expertly restored, and are the most complete examples which I have seen. They were painted entirely black which makes photographs more difficult to interpret.

Whales are commonly seen in the bay. Unfortunately none on this day.

This is a close up of the projectile loading cradle. The deep groove at 6 o’clock caused me to re-examine the history of studded projectiles and non studded gas check projectiles. Apparently the studded type were used until the mid 1880’s but were discontinued when gas checks were introduced. Gas checks were effective and caused less bore erosion wear than the studded type. The groove at 6 o’clock would have accommodated the lowermost stud. The cradle would have continued to be used with the gas check projectiles.

Next post will include some interesting historical photos, and other restored cannons which were recently installed at Port Fairy.

A (model) Cannon for Christmas

Christmas 2020 seemed to hold particular significance. Our children, their families, grandchildren all congregated and had a superb vegetarian meal with food preparation shared. Vegetarian, because a majority of our extended family are now vegetarian. One is a vegan, and some of us are inching our way towards that aim. Even the omnivores are mostly reducing their meat intake.

We enjoyed some lovely Australian wines, with Pavarotti in the background.

This was the first time that the whole family has been together for 9 months.

Everyone had a hand in food preparation. Two Hands Shiraz 2017.
Perfect weather. 25ºc. The grand-kids had a separate table outside. A very happy gathering. 3 daughters on the right. Sons in law and a family friend on the left. You know who at the end.

The grandchildren had been forbidden to get up for presents before 6am. And my son in law set their clock back an hour! So it was a leisurely start to the day. 7am.

We usually do a Kris Kringle for adult presents, but this year, we just decided to have no restrictions.

I had wondered (and to be honest, been slightly anxious) how the model Armstrong RML cannon would be received by my son in law (front) and youngest daughter (right front). Neither of them have any interest in weaponry or military history. My son in law grew up in Port Fairy where the original full size cannons are slowly rusting away. And my daughter took part in 2 casting sessions to see what casting was about. But neither had any idea that the model cannon was for them, and apart from the aluminium casting, neither had seen the cannon gradually being made.

Their reaction exceeded my most hopeful expectations. Both became teary, as did I.

The following video was made by my daughter. The daggy paper hats are part of our celebration. Totally unscripted. And I have had a few by this stage of the day.

rosy cheeks. Must be something in the water.

Aluminium Bronze

I bought this 100 year old French vase for SWMBO for Xmas. I had no idea what its value was, but just loved the decorations, colours and shiny surface. It is quite small, and would hold only one flower if used as a specimen vase.

But….

It had no base. Was open at both ends. And had been slightly damaged from being top heavy and falling over for the previous owner on several occasions.

The damage had been professionally repaired. As you can see from the photos, the vase is quite exquisite.

The antique dealer, with whom I have dealt on many occasions, has had a tough few years. Antiques of all types had really become unfashionable. I asked how things had been in 2020, and was very surprised to hear… “Business is booming. Never been busier. Despite viewing by appointment only for most of 2020.” Which I was very happy to hear, because Moorabool Antiques, in Ryrie St Geelong, is one shop that I always enjoy browsing, and chatting to the very knowledgable staff.

Since the vase had no base, he said that it was much cheaper than if complete. It was still quite costly, but I am pretty sure that SWMBO will like it.

And……I am pretty sure that a half competent machinist could make a base for it. Paul, the Moorabool Antiques proprietor was interested. I showed him a photo of my model Armstrong cannon, and he became VERY interested. We discussed designs and materials for the base, and methods of attachment. It would have to be water tight if it will be used as a specimen vase. The attachment method would have to not affect the existing structure or decorations. I mentioned Super Glue. Paul suggested Silicone. So Silicone it will be.

I searched Google Images for similar vases, and discovered at least a dozen designs by the same artist, Alexandre Marty. It is Limoges enamel over silver foil on copper. And as you can see from the photo of the similar example with a base, the missing base was probably gilded brass or copper or bronze.

I searched my workshop for bronze/brass/copper of sufficient size, and found some copper, LG2 bronze, aluminium bronze and brass. After looking up the properties of the materials which I had to hand, I chose the aluminium bronze. As the name suggests, al-br is mainly copper, with aluminium being the second constituent. It is particularly resistant to corrosion so is commonly used in marine applications, such as propellors.

First I turned a shoulder which would loosely fit into the base of the vase. Then cut off a 10mm disk.
The alu bronze turned really nicely. The hardest aspect was the tiny lip (2mm) that the lathe chuck gripped. The workpiece came free from the chuck several times. I probably should have drilled a central hole and attached a rod through the headstock of the lathe. And filled the hole when finished. (But I didn’t.)

Can you see the gold coloured rebate? That colour developed when the workpiece became hot during machining. That gold colour is a property of al-br, and is often used by jewellers. I slowed the feed-rate to avoid further heating, and got the contrast from the other bronze coloured surfaces. It will be interesting to see what happens to the colours with time. Although the vase base diameter has increased only by 10mm, it is much heavier, and should resist toppling.

The result, and the image of another M. Alexandre Marty vase which I used as a model for the base.
Just to show that my life is not all gunpowder, cannons and steam.

Who Would Like a CANNON for Christmas?

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

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

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

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

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

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

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

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

Wooden Base for Model Cannon

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

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

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

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

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

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

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

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

Then I read the rest of the label….

!!