I've just bought 1944 Colchester lathe (a "pig in a poke", £50 on eBay UK, 113 euros transport to France where I live, it has very little wear for a sixty year old machine!), my intention is to"CNC" it. It came without change wheels, intend to use the Electronic Lead Screw being developed on the ELS yahoo group. The ELS will allow threading and taper turning, and for "real" CNC, I'll go over to EMC and Linux, this also gives me time to learn G code ans stuff! Mechanically I can cope with this project, but I need help with the maths involved. Thirty five years ago, when training as a mechanic, I learnt to check bearing preload on differentials (third members for our American cousins) using a piece of string and a spring balance. I've only ever done this once in my life, as fate has it I've never had to rebuild a diff since! Today I wound a piece of string around a 25mm diameter part of the cross slide screw, pulled it with a spring balance and obtained a read out of 800grams. Can anybody out there help me with the calcuations to transform this into stepper motor torque.
Matthew TINKER (Tinker is my real name!)