[ger21]

So an increase in dia, and/or a decrease in pitch will result in less effort required.

But an increase in diameter increases inertia, which can require more effort to get it turning.

[Goemon]

But an increase in diameter increases inertia, which can require more effort to get it turning.

Do you think I should buy a larger motor for my long axis then (the one that has the larger diameter screw)? I currently have the 381oz "low inductance" motors that many here start with.

looking at the specs for these motors, they seem to have a decent amount of torque and peak torque for the job but i'm not really sure how much torque is optimal for this purpose. My inclination is to wait and see how well these motors cope before deciding to upgrade or not but.... if I am going to need to invest in new motor mounts and motor couplings plus redesigning the axis to make them fit, it would be easier to do that now if you think I'm likely to need more juice?

If I can do what I need with the 381oz motors then I would prefer to wait until I am ready to upgrade to a decent servo set-up.