Now that I have a proof of concept on the front crank pins, I returned to the brake linkages.
The linkage that connects the cylinder with the brake pull rods is supplied as a pair of etches that are laminated together. – Parts AA/AB in the diagram below.
I decided to see what I could come up with as an 3D compromise. So I butchered the etches and then laminated them together with some additional parts turned/milled from rod.
Which gave me these:
Next, I added strips of nickel to the two etches which support the brake linkages behind the brake cylinder.
I did need to cut one of them to accommodate the motor, but I preferred to cut it after I had made them up. You can see that there is a half-etched cut line to allow for this.
Next, I went to fit them and that’s where life got interesting again. If I soldered them into the slots in the horizontal plate as intended, I lost access to the screws which hold the rear springs on. I am pretty sure that during the course of fitting the motor and get it running, that I will no doubt need to remove the rear springs at some point.
My solution was to make a small plate from scrap etch which could be soldered in between the two frames and then drilled for a 10ba screw. I had to make a little jig from the 10 BA screw and a piece of spare rod and some washers to space the top part of the frames the right width to allow me to solder the plate in at the bottom. I made it slightly trickier for myself by electing to make it precise enough that the frames still located in the slots. Soldering the base plate on took a couple of attempts before I was happy that it sat correctly.
Then it was a fairly simple matter to drill 10BA clearance (1.8mm) and solder a nut on the frame. This allows for the screw to screw in from the top of the chassis on the basis that it’s less likely to drop out in motion that way.
As an aside I was really surprised that the stub on the base of the brake cylinder was a really snug push fit in the hole snapping into place when I pushed it home. I was surprised because I hadn’t thought to measure the hole prior to assembly of the frames and measuring it accurately was quite difficult with the tools I have.
In the view from the top of the frames above you can see the screw and the tabs of the frames located in the slots tightening the screw makes them snap into place quite easily.