Quote Originally Posted by A_Camera View Post
I think you are wrong about gearing. Torque is multiplied by the gearing, so indeed I gain a lot. Of course, since the stepper is pretty weak, it will not be much at high RPM, but never the less, it will be six times (minus some losses, but we can ignore that here). Of course, gearing down is giving the most torque benefits in holding, but there is a benefit even when rotating. Of course, that would not be needed at all if I had a large enough motor, but that's for later times.
You seem happy to redefine terminology, which is fine but may cause confusion when you try to communicate with others.

Have a look at the torque-speed curves for the stepper motor you are considering. If you fitted a 2:1 reduction gear you'd double the stall torque perhaps. But if the torque at a new, doubled operating speed had dropped to half of what it was, you'd have gained nothing - you'd now have the same final torque at the same speed but you would have halved your max speed (the all important "rapids"!). My conclusion is that you might as well go direct drive with steppers.

For a servo it's different - you really need to step the speed down by a factor of 2 or 3 to boost the final torque to something more generally useful. Also, not many ballscrews will be happy to run at the max speed of a servo which is usually around 3000rpm, give or take. So to me, steppers are best used in direct drive and servos best used with a belt drive reduction ratio of between 2 or 3. But as I said, there's no right or wrong!