Gerry, Thanks! you're right. Even though they specified single start in thier email quote the part number lists it as four start in the catalog.
Back to the drawing board. Looked at the motor last night and the bronze integral nut appears to be pressed in. I think I'll try pressing out the old motor nut and see whats what and maybe switch it for something more readily available. Have to keep the mechanical gearing though as the logic is all on one big board..
The small diameter single start screw is needed to move the plotter head at high speed and accuracy (0.0006" supposedly) with very little load. The motor is a bit wierd, it's wired eight wire bipolar parallel, 0.8 degree 400 step, 1.2v 4A 4.2kg-m (about 44oz-in?) but rated to 3600rpm! That ties up with the 800ipm rated speed of the plotter.
off to dig out that arbor press... |