Armstrong Cannon Wheel Assemblies -2
by John
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.
Here is the main component of the left hand rear chassis bracket, being held in position. It will be bolted on later, and have several flanges silver soldered to it. Those M2 cap screws will be replaced by rivets eventually.
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.
2.5 hours to print PLA examples of rear (left) and front king pin casings. I need to see the original cannon to check some details before committing to cast these in bronze. The PLA parts will disappear during during the casting process. (A pity. They are quite attractive No?) You can see why I chose not to machine them out of bar stock. 3 pin holes in the left hand print ? the result of not storing the PLA spool in a dehumidified container.
So, it might not look like several days of computer and workshop time, but that is how long it has taken.
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.
johnsmachines 
John, Great stuff, can’t wait to see the castings.
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Thanks Rob. Yes, casting looks interesting and exciting. My colleague Stuart has been doing aluminium casting quite successfully with the lost PLA method, so I am hoping that it will work as well with bronze. Stay tuned. Pictures and videos will doubtless follow. John
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Hi John, All looks very good, well done. It would be a shame to lose the patterns. I’ve little experience of casting, only poking a hole in a bucket of sand and filling with molten brass from swarf, ofcuts, stuff ups etc. result- a good piece of one inch brass bar 10 inches long – saves a bit of cost. Could you do the same with the little patterns? thereby saving them in case a repeat is required.
My next project is a horizontal mill engine, just sent off for the drawings.
Hope you got my email re the Great Arc.
Have fun casting. Chris.
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Hi Chris, yes I saw the Great Arc thank you, and have read a bit about it previously. Re casting, it is all new to me, except for a bit of lead casting which hardly counts. PLA acts like lost wax, so the mould disappears. But being 3D printed, I can reproduce as many as I want. John
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So I got to drop by and have a read today. Jolly good as usual John thanks for the read.
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Thanks John. I needed a bit of reader feedback. John
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If I am hearing correctly you will soon be Warnambool bound but there seems some confusion about only one night stay rather than a few days which would allow detailed examination of said canon.
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John, a few hours will be plenty for what I need to do. I believe that the Warnambool cannon is identical to the Port Fairy and Portland cannons, except possibly more complete and in better condition. John
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