Hood,
I need the motor for my Emco F1 spindle. The original one is a DC motor 4000RPM, 440W, 1Nm, geared down 2:1, so at the spindle I get max speed of only 2000RPM (not really enough for most of my work) and torque of 2Nm. The torque is a bit insufficient at times, but I think an AC servo with the same continuous stall torque rating would do much better, since it can ramp up to it's peak torque much faster and stay there for longer times.
Getting a bigger motor - that was what I was thinking to do before I took apart the F1's head. The timing pulley mounts on a 35mm shaft, setting the limit to how small a pulley I can use, and the head housing limits the max pulley diameter I can put on the motor - about 70mm. So gearing down 1:1.5 seems to be the best I can do. Thus using a 8,000RPM motor I should be able to get 12,000RPM at the spindle - which is what I am aiming for.
But may be you're right, I'll need to compromise on a lower speed. May be I can find a 6,000RPM and get 9,000RPM at the spindle.
Thought using a High Speed VFD spindle, but it would limit me to a lower speed of 4,000RPM (if geared down 2:1).
Daniel