MOK 8F – Replacment 3D Printed Tender Brake Blocks

Some time ago a fellow modeller who was building the same kit had some 3D printed brake shoes done. He very kindly sent me a set and they have been sat waiting patiently ever since.

While working on the other bits over Christmas I have been pondering the best way how to tackle fitting these. The brake hangers on Stanier tenders are curved so to replicate these my thoughts ranged from turning circular strips from sheet to bending strips from flat bar. In the end I gave my self a mental kick and thought why are you trying to ‘save’ the castings, you will never use them now that you have fitted 3D printed replacements.

So the next thought was right I need to remove the cast on, shoes from the hangers. Ian, the guy that had supplied the printed shoes also sent a note with some suggestions as to how to go about it. His first suggestion was to use the pips on the cast shoes as the location for drilling out the hole for the pin. I duly filed the pip down on one side of each casting until it was just a witness mark and then punched it. I used a pin vice to drill the first one and though sod this for a game. I drilled a hole in a lolly stick to take a 1mm drill bit (the same sized hole as the top of the hanger). I popped the leg of the hanger in the vice along with the bottom of the drill bit, which was inserted through the hanger and then the lolly stick. This held the casting firm enough to drill through it with my Proxxon mini pillar drill. The rest of the drilling was done in no time.

I tried the same set up to hold the casting to file off the bulk of the cast on shoe but using a file was hard work so my thoughts turned to milling them off. To use the mill I needed to hold them much more securely than a piece of lolly stick would allow. So I made a fixture from a piece of brass bar.

Fixture for holding brake castings while milling.

For the first side I just drilled a couple of holes at the appropriate spacing to hold the leg of the casting and the drill bit passed through the hole as before.

For the reverse side I didn’t have the leg to give me the secure holding so I milled a bit off cutting art way through the leg hole

Machining a Fixture for holding brake castings while milling.
Fixture for holding brake castings while milling.

Which gave me this.

Fixture for holding brake castings while milling.

Once both sides were milled I used a mini sanding drum in my Dremel to take off the last bit and restore the inner curve.

MOK 8F 3D Printed Brake shoes fitted

The last task was to insert some brass pins and superglue them in place while allowing the shoe to still pivot.

Next job is refitting them to the tender chassis as I had already fitted them some time ago.