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.

Tag: Cannon Chassis

Armstrong Cannon Chassis Wheel Assemblies

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.

PANA3825

The 2 chassis’ are not identical.  Can you spot the differences?  And still waiting for more rivets to arrive.  The copper colour on the front one resulted from dipping it in well used sulphuric acid after some silver soldering.

 

Considering how to model these wheel assemblies…..

front wheel and mounts

The front wheel assemblies

rear wheel and support

The rear 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.)

Small Steps. Armstrong Cannon.

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.

PANA3776

There is a 4º angle at each end, and a 6º slope along the bottom of each girder.  Also, the top flange is 11.5mm wide, and the bottom flange is 14mm wide.

PANA3773

Setting up for the bottom 6º angle.  The 4º ends had been machined before this.

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.

Armstrong RML. The Chassis -1

 

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.

P1053549

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.

 

chassis R rear obl

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…

P1053742

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…..