School starts, and I'm busy again. I have all sorts of cool things to write about, and not enough time to do so. But I'm on top of homework, so here's the conclusion to the combination lock saga!
I wish I could describe the measurements better, but that's a job for engineering drawings, not text. I'll see about making some proper drawings soon.
After deciding on about half the dimensions, we started cutting. The tumblers and washers were first, then I popped a few dowels onto the lathe to turn them down a bit. When I finished, the tumblers spun smoothly on the central shaft.
We assembled the core of the lock with brass screws. First, we slid a washer onto the central shaft, then a tumbler, another washer, and so on until it was built up. After a quick test to make sure everything interfaced well, we screwed the washers into the central dowel with brass screws, being careful to keep the tumblers under a bit of pressure (to prevent wobble and slippage).