Kollmorgen PMI servodisc U12M4

[lucas]

These look like great motors from their spec's: 128 oz-in continous torque, peak 1316 oz-in, 284 watt power output and the special construction gives more advantages. small disadvantage: no encoder.
I might be able to buy 4 of these locally, probably cheap compared to EBAY "buy now" pricing but there are no bids on them...
So what's the catch, are these good and what is a decent price?
I already burned my fingers on 4 good looking steppers and don't want it twice.

Thanks for the advice.
Luc.

[Mariss Freimanis]

You might want to reconsider. Those motors have very low inductance and cannot be used with most servomotor drives.

Mariss

[lucas]

Mariss,

thanks for the reply, I felt something was wrong and you saved me some $$$'s.
No iron in the rotor causes the low inductance, current rises very fast when PWM'd and the drives can't handle this?

BTW: do you have more info on these 8 wire steppers:
http://www.cnczone.com/forums/showthread.php?t=16228
These are the ones I bought and can't get to work properly.

Thanks again,
Luc.