I am looking for information regarding the torque fall off of stepper motors over the RPM bandwidth they support.
Specially Mach3 -> Gecko -> 600-1800Oz/Inch motor.
My focus is on the range between 0 and 800 RPM. 0 is easy, that's the rated holding torque.
After that it goes down hill. But how fast?  Guesstimations range from 20% to 65% left at 1000RPM.
Any pointer to more information or where to find motor curves would be great.
Lemo

Lemo,

The first place I would look is the manufacturer of your motors. Usually they provide the information you are looking for. Try looking for a website and go look at the technical specs for your motor model numbers.

On some of the imported hobby stuff it may be a challenge to find this info. Also if the motor was made for an OEM to their specs you may be out of luck.

The only other option is to test them on a motor dyno.

Monty