lead screw question

[tkms002]

So, it seems that I should be using a multi start lead screw to be able to move fast enough. I see that when you use a rack and pinion you move too fast unless you gear down the stepper so my question is, can I use a much less expensive single start lead screw and gear the stepper up?
Bruce

[restless1]

what axis is rack driven and what axis will have a screw..
on mine i have two racks along the y axis and one on the x axis and a screw for the z! So my z only moves a short distance anyways..
also how big is your table how much are you traveling?

[ger21]

can I use a much less expensive single start lead screw and gear the stepper up?

Yes, but it's not as efficient as using a multi start screw.

A single start 1/2-10 acme is only about 35% efficient, so it wastes 60% of the torque.

A multistart thread will be 60-75% efficient.

So, while the motor will turn much slower with gearing, you're still losing almost double the power due to inefficiency.

You'll also be more likely to get screw whip, due to the faster spinning screw.