My pulleys and drive belts arrived today.
I removed the grub screws and drilled out the 48-tooth pulleys to 6mm (from 5mm) in the lathe to fit the worm spindles and the 16-tooth pulleys to 5mm (from 3mm) to fit the stepper motors. I chose to use the lathe rather than the pillar drill purely to give me a better chance of keeping the bores central. Unfortunately that’s pretty much all I can do for now, though the stepper motor spindles don’t have a flat so I may need to grind one for the grub screw to bear on if it doesn’t work without.
I need to cut a 22mm hole in the mounting brackets for the motor body to sit in, but that will be much easier to do with a 22mm drill in the pillar drill rather than trying to centre an oddly-shaped piece of material in the lathe, taking it out to about 18mm with a drill and then boring the hole out the rest of the way.
I don’t have a 22mm drill bit at the moment, but one is on order. As soon as I have that I can get on with cutting those holes, drilling the mounting brackets for the motor mounting screws and assembling all the parts. After that I think it’s just cabling that will be left.