I’m making the 5cc Sparey Diesel to Hemingway’s plans. The crankshaft is specified as from 1.25″ dia steel bar. In particular, the overhung crank-pin looks to be an awkward machining operation. I’m wondering if a press-fit or loctite assembly might be OK. Perhaps also even for the crank web onto the shaft itself.
machining is not too hard, you can either use a keats type angle plate or bore a block of aluminium to clamp the shaft in then the block can be held in the 4 Jaw. If going for an integral pin then you can mill a lot of the waste away to leave a small square that can be easily turned and a clean up facing cut to the web.
I have also done pressed in silver steel pins, a hand reamer not run all the way through will leave a taper that grips the pin more the further it is pressed in.
Thanks for such a quick response JasonB. How do you manage such relevant pictures at a moments notice? My Keats angle plate is a fairly big thing and doesn’t really appeal for this job. The aluminium block looks better to me, but the shaft will need tight clamping. i think that might be the way to go though.