Craig,
Thanks for the detailed response and the time taken to compose it..
I do understand the rotational of inertia of the ballscrew dominates.
I also understand the multiplying effect of the ballscrew, A simple nut and bolt generates an amazing amount of force even with modest torque applied.
I will use the largest small diameter pulley that will allow a 2-3:1 ratio to maximize ribs engaged.
Out of curiosity, what series of 15mm wide belt/pulleys are you using?
Cheers,
Jeff