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. n.b. There is a list of my first 800 posts in my post of 17 June 2021, titled "800 Posts"

Option 1. Ironwood.

The problem was that the 4 wheel brackets needed the wheel recess deepened by 2.5mm, and the brass shape had few clampable surfaces.

So, I tried option 1.

I machined a wooden jig to hold the bracket in the milling machine vice. The wood is Australian desert ironwood, which is unbelievably hard, but would not mark the brass. The pocket was machined to the diameter of the circular base of the bracket, and then sawn in half.

The bracket was clamped in the jig and squeezed tightly in the vice. Then machined with the slot cutter, the required 2.5mm deeper. The workpiece showed NO tendency to move.

Mission Accomplished!

Cannon Wheel Brackets. Cast or Machine?

Original brackets on the Elsternwick 80pr Armstrong RML’s. They appear to be castings.
Another wheel bracket style. This one on the Armstrong 80pr at Port Fairy. Cast from a different mold.

Previously I have made model wheel brackets using 2 different methods…. 1. casting 2.turning/milling

This bracket was cast from aluminium. It looks different from the Elsternwick example above, but is close to the original Port Fairy original.
This one was turned from brass, and was installed on the model copied from the Elsternwick originals. Not too dissimilar from the original, but still not quite right.

So, these are the wheel brackets which I have made for the current model Armstrong 110pr…

These are hot off the milling machine, and not yet finished. Those sharp edges will all be rounded and milling marks polished out.

I think that when these are finished they will look closer to the original than either of the previous examples, and they certainly look more robust and fit for purpose IMO. So, what do you think?

The above wheel brackets were milled from 38mm brass rod….

12.7mm 3 flute HSS endmill, 8mm deep cuts, CNC mill.
The slot was cut with a 5mm width slotter. 3 passes to get 11mm width. First pass shown here.
75mm diameter, 5mm thick slotter. Shop made spindle fits into ER40 chuck. First ever use of this slotter which I bought years ago.

On reviewing this post I noticed that the slot for the wheel looked a bit shallow, and when I measured it I found that it is 2.5mm too shallow. A simple mistake, but must be fixed.

The problem is how to hold the workpiece while cutting the slot the extra 2.5mm deeper.

Possibilities. 1. make a circular jig to clamp the bracket in the milling vice. 2. just hold the bracket in the milling vice and hope for the best. 3.solder a 38mm cylinder to the top of the bracket, and hold the extension in the vice. 4. make new brackets.

At this moment I am thinking that I will try 1. and if unsuccessful move to 4.

Watch this space…..