Loco about Locos

The cylinders on this loco are gunmetal. Simply because that's what came with the bits I bought! I much prefer gunmetal anyway. I don't run my locos a lot, and worry that cast iron cylinders will rust. The other side of the coin is that you can use conventional piston rings with CI cylinders. The first thing I did was to make up the boring bars. Mine were cross drilled bar, of as big a diameter as could pass through the cast bore - within reason. I have quite a few carbide drills intended for drilling glass fibre printed circuit boards. They do have their uses -but are very fragile. They all have a 3mm shank, which is ideal for making small cutters. They're easily ground using a diamond wheel (but nothing else will do !) The tip is held in the boring bar by one grubscrew which presses on the shank of the cutter, and another grubscrew behind it, which is also used to control the advance of the cutter. I needed to make more than one cutter with different lengths, or a ...

I started with a set of frames which had already been made. I was going to say - which saved a lot of sawing - but in fact I would probably have cut them in the mill. The important thing is that the two blanks are riveted together and treat as a pair until complete. As I had no idea how mine had been done, I started with dimensional checks. I soon found that the axle box spacing was marginally different (of the order of 20 thou) from one side to the other. And the horn slots had been finished individually and were different (hence the axle box spacing). Apart from that, they seemed ok. I set the frames on parallels standing on a surface table. The structure was not truly parallel, with a rock of at least 1/16 in in one corner. I slackened fixings and kept rechecking, until I found that the central cross braces were the cause of the problem - one was a few thou out of parallel. I milled a few thou off to make it truly parallel, and made up a shim (only 5 thou) to keep the spacing correc...