Wednesday 22 March 2023

Printing Wagon Details

Another piece of work over the last few weeks has been designing and printing some wagon details. 

I am finishing off some wagons pending transfers. In the process I am adding bearings to allow the stock to run more freely. This has sometimes necessitated cutting off the solebar to allow the bearings to be fitted and the solebars to go back on slightly further apart. This isn't an issue since 009 track is technically 1mm narrower than it should be for the Welshpool & Llanfair, so could be argued that it is putting the solebar back to the correct dimensions... 

The process of removing the solebar did result in damage to the brake lever and the brake shoe. Looking around at how to replace them, I did consider the easy way of buying them but couldn't be sure that any on the market were of the correct length. That led me to deciding to print them. 

Looking at the open wagon page in the Glyn Williams book revealed a couple of points I had previously missed. The first is that the brake lever doesn't lie flat against the solebar as I had been modelling them. It actually comes out at a fairly steep angle to the edge of the wagon. The second point I had missed is that the brake lever assembly is fixed to the wagon by a bracket that comes out from under the wagon and up the side of it.

It would make a complicated part but could it be printed?

This is what I was able to come up with. It has a thick spigot at the back of the ratchet assembly. this provides a good surface to glue the assembly onto the wagon. More importantly, it helps it hold a vertical shape.

The piece of the bracket that comes out from under the wagon is very fine and I had to put a fine cut out in the inside right angle to prevent resin pooling there that would prevent it sitting flat on the wagon. the part is far too fragile to cut or file.

The photo suffers from being blown up horribly but it's clear it can be printed and, once glued onto the wagon, is pretty strong.

I used a different resin for this print. Talking to someone demonstrating at the Southampton show recently, I learnt that he uses an abs-like resin for final prints as this is less brittle so more tolerant of  knocks. I decided this would be a good part on which to try such a resin as it is a very vulnerable part, likely to get damaged with handling. The real drawback to abs-like resin is that it is not available in a low odour form so really does smell.

I know I am taking 3D printing to the limit here. On a few of the levers it managed to print the gap in the ratchet part of the assembly, despite being only 0.4mm wide.

The ones for the vans will have to be done at some point but this has pointed the way to a plentiful source of replacements. Then there is the brake shoes...

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