Each brake pad is attached to a curved frame that has a pivot hole at each end. The whole assembly is pretty nearly 2D, and I thought laser cutting was an option but I discovered that the process wouldn't allow the small pivot holes to be cut accurately enough (and perhaps not at all) in what is quite thick material. So back to the traditional methods, and with lots of little parts, and multiple parts at that, another jig is called for.
This jig is mainly made from a nice offcut of hardwood. Metal would suck all the heat out of the soldering iron. The pivots are simple turnings and are held vertically on accurately located pins. The frame itself is rolled from brass strip.
The next photo show these parts assembled in the jig ready for soldering.
And here is a "before and after" photo. On the right are the first few frames assembled, on the left some rolled strip for the next few, and in the background the turned pivots.
Now the soldering jig is turned into a drilling jig to make one hole to attach the brake pad and another for the crossbars that run between adjacent brakes on opposite sides of the tender. The holes themselves were first drilled in a spare piece of curved frame material and act as a guide for drilling the actual frames.
And here is the finished product. Next up will be the brake pads.
Nick
