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.
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.
But this post is about my recent 2021 holiday in Port Fairy.
I spent some hours checking and getting more measurements……….
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.
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.
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.
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.
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.
Next post will include some interesting historical photos, and other restored cannons which were recently installed at Port Fairy.
1:10 Model Armstrong rifled muzzle loading 80lb cannon WILL be ready for Xmas.
Apart from minor touch-ups, the model and painting is completed.
I will take some careful photos before it goes to its final home, but here are a few snaps to show how it appears with some paint and lacquer.
So, was SWMBO correct about not painting the chassis? I like the look of this finish scheme, but now have to decide what to do in that regard with the “A” model, which was put aside while I finished this one.
p.s. I weighed the model, because I was curious. The full size original barrel weighed 81.5cwt/4.1 tons plus the carriage/chassis, about 5 tons/5080kg total. The 1:10 scale model should weigh 0.1 x 0.1 x 0.1 or 1/1000th of that which would be 5kg/11lbs. It actually weighs a tad under 10kg/22lbs which is almost exactly double the predicted. It is a bit of a lump to carry around and I do NOT know where the extra weight came from. Or maybe my mathematical assumptions are incorrect.
(note added 1 March 2021. See the post added 1 March 2021. The total weight of the gun barrel, carriage, and slide – which I have been calling the chassis, was close to 10 tons! So my assumption that the model should weigh 1/1000th of the original was very close to correct!)
First, I have decided to NOT rivet the final joins of the chassis. Instead I am using dome head stainless steel bolts and nuts. The main reason is that the other end of the rivets are in impossibly small (for me) cavities and spaces, and I could predict that the final riveting result would be horrible. Even using threaded rivets would be incredibly difficult. This decision does cause me to reflect on the 1866 cannon builders who managed such perfect results with red hot rivets in confined spaces, and again, to be awed.
To divert, back to the painting.
Question. When painting a model, is it best to assemble the whole model then paint, or to completely disassemble every part, paint the parts then reassemble?
1. Disassemble and paint the parts then reassemble. This results in complete paint coverage of all parts. It results in clean separation of different coloured parts. Mistakes involve limited areas and are easier to correct. However, the thickness of the paint can alter carefully machined tolerances. And surfaces can be painted which were intended to be unpainted.
2. Assemble the entire model, then paint. This can make some recesses, corners and hidden areas difficult to access. But the appearance of the entire model can be assessed as the painting progresses, and major mistakes in colour choice can be corrected. The painting process does not alter dimensions or fitting together of components. But paint edges and joins can be difficult to keep neat and straight, particularly in my inexpert hands.
3. (Obviously what I chose to do). Partial assembly, into modules, then paint the modules separately. This has the advantages of both 1 and 2. The modules can be stacked together to periodically assess the results. The modules are smaller than the complete model, and easier to handle. Difficult decisions regarding colour, or whether to paint at all, can be deferred until the easier parts are painted, and some idea of appearance ascertained progressively.
So that is what I am doing. I have painted the bottom part of the chassis, and the carriage. Etch primer at this time, but already firming up ideas about final colour. And my colour and design expert advisor (SWMBO) has had some input into this decision.
At this stage, I asked for advice from SWMBO. She has suggested that the primed modules should be painted satin black, which should contrast nicely with the brass/bronze components. Avoiding gloss will minimise the finishing defects. Some filling of defects will be required in any case. The black colour will be tested on the carriage, and if it looks OK, the chassis subframe will receive the same colour.
SWMBO’s most interesting suggestion is to NOT paint the main chassis beams at all! Well, a clear lacquer will be required to prevent rust.
But. What about disguising the copper rivets/stainless bolts?
SWMBO: “they look interesting. Leave them.”
Me: “but, but, but, they do not look authentic.”
SWMBO: “This has to look like a work of art, otherwise it will be just a boring dust gatherer.”
It took a whole day making and fitting the top caps of the trunnion mounts from brass.
A 76 x 76mm piece of brass was milled to 10mm thickness. The trunnion straps will finish at 9.5mm , giving me a 0.5mm machining allowance.
The 4 straps were cut out using a new 4mm endmill. Rounded internal corners were milled square, and the bottom tabs were milled to 2mm thickness.
2mm wide slots were milled into the brackets, and ends of the slots were filed square. None of my rifling files were small enough, so I ground one to size, leaving the faces and one edge intact.
Trunnion mount almost finished. Pins in the tags to come, and they will pull the strap down tight with a cam action. The half circle line on the bottom bearing is a painting border to delineate the bottom bracket from the bronze bearing surface which will not be painted. If you inspect the full size trunnion in the previous post you will see what I mean.
Now I can take some measurements of the model, and start the barrel elevating gear. There are 4 gears to be cut, including bevel gears, handle, shafts, gear case, and some complex mounts.
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.
The Colchester 3 jaw is 200mm diameter, and it neatly holds a 80mm chuck off my Boxford TCL125 CNC lathe, which holds the part. It is a centre column from the scale model Armstrong gun which I am currently assembling/making. It is a bit irregular, with thin 2mm flanges and fins. I really did not want to damage it, but it needed 1-2mm trimmed from its height.
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.
I machined the three castings which I had made. And reversed them to machine the bases. The setup worked well. I need only 2 of these, and could use any of them. The machining did reveal some porosity of the castings, but overall I am quite pleased with the end result.
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.
Not a great photo. It shows a front wheel, 33mm diameter, turned from stainless steel. No axle yet.
And a rear wheel, 50mm diameter. Yet to have the track groove turned into the periphery.
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.
For some reason which I do not really understand, my youngest daughter has become interested in my metal casting activities.
First she watched me do a molten aluminium pour.
Then she rang me a day or two later and asked if she could have a go. She really wanted to do it in brass or bronze, but as a relative beginner myself, and with only one episode of molten brass, and that one did not go so well, I demurred, and said that her first effort would have to be in aluminium.
So I prepared 3 flasks, printing the plastic parts, and gluing them into a wax tree, then slowly heating the flasks in the potters oven, up to 750ºc over 8 hours. Then lowered the oven temperature to the pouring temp of 710ºc. And preparing the aluminium melt at 710ºc.
When Eleanor arrived, we had a couple of practice runs with flasks full of sand, so she could get used to the weights and handling the tongs, and the various movements while wearing the protective gear.
Then the pour. This is Eleanor’s video of the event.
I admit to some substantial reservations about this exercise, but Eleanor listens carefully, asks intelligent penetrating questions, and follows instructions precisely. Full marks.
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.
The box section is an assembly of parts. The ends were silver soldered. The panels which show are steel, and will all eventually be riveted to the end sections. At this time, some joins are still just bolted and nutted.
This is the front of the chassis. The rivets look OK yes?
And the inside rivets were the first ones to be inserted. Mostly worked OK. They are copper, will eventually be painted the same colour as the girders.
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.
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.
The mill drill setup. Re- indicating the vices again took me about 45″.
Firstly all of the holes were center drilled, then drilled through. The rivet confirmed a nice sliding fit.
364 holes, through 5mm of steel done with one center drill, and one 2mm drill. That is pretty impressive IMO. More than 1.8 meters of steel with 2 drill bits. And using my olive oil and kerosene lubricant-coolant. And the bits still seem to be sharp.
Each girder took about 28″ to drill the 91 holes. CNC of course. It has been a while since I said it….. “I love CNC”.