Stepper motor determination

[praetor]

Does anyone know how to determine the volts, amps and possibly torque/Oz. of unlisted stepper motors? Take the pics, for example, it's one of two Shinanao Kenshi stepper motors and the only info on them are STH-55D405, 154071-001 Rev. R, No. 05880G?

[Mariss Freimanis]

It looks like a double-stack NEMA-23 motor. Double-stack means it's 2x50 in-oz or 100 in-oz holding torque. A motor like that is 8 Watts per coil. Measure the coil resistance. Knowing I^2 * R = Watts, rearrange to solve for I. I = SQRT (W / R) which will give you the rated phase current.

Mariss