Quote Originally Posted by Kitwn View Post
I've read this recommendation several times but doesn't the increase in pitch cancel out the increase in torque so that the maximum linear force that can be applied to the gantry without stalling the motor remains the same? Or are you more concerned about the moment of inertia of the ballscrew itself?

Kit
Kind of yes but no, or should say maybe your misunderstanding what's being said or maybe I'm not putting it over clear enough..

Yes, 32mm pitch with 2:1 ratio will give the same linear torque as 16mm pitch 1:1 so torque is canceled by pitch difference like you say.
However, when I say Torque is doubled so the smaller motor can be used, what I'm referring to is that if 1:1 the 32mm pitch would require a larger motor to give the same linear force as 16mm pitch. So the ratio doubles the torque and allows the smaller motor to have the same linear force as 16mm pitch.

The trades off's and gains are that 32mm linear movement halves but so does rotation speed of the nut. So the pay off is that you get the same feed and torque as 16mm at 1;1 but with half the rotational speed of the nut or screw. This is the main goal to reduce whip and stress on the ballnut.

Hope that makes more sense.!