Originally Posted by
scottyd
Oh, something ive got experience in!
I made up some 5J sheaves for my hercus lathe to replace the motor to layshaft belt arrangement as it comes from the factory. I have a 2hp single phase motor in my machine, but it spins at twice the rpm as the original, so it affected the speeds that the lathe would turn at. I did some work on designing a pair of two step sheaves, I ended up going with some 1018 (i believe, scrap bin diving, but the owner of the workshop reckoned thats what it was) stock for both sheaves, which I cut on a hercus 260.
I think steel was a bit ambitious. To cut the vees, I would plunge .2mm at a time, then wiggle either side by .1mm, recentred and repeat. Measurement was with a ground pin i had, 1.5mm dia, to the other flat opposite. It took a bit of fiddling to get a good shape on the tool so that chatter wasnt a massive problem, but my lathe isnt very rigid and, because of the original pulley / motor combo, i couldnt slow it down as much as id have liked. If I was to do it again, id go with alu plate, largely because itd suit my speeds already available. Cast would be great as well, but finding some could be tricky. Because of the dumpster stock I had to pick from, I was actually using seamless pipe for the sheave and a seperate piece of steel as a hub. I did get the required dimensions in the end, but i had to cut so so gently.