[ger21]

If you are using steppers, you want between 10mm and 20mm pitch. With servos, I'd go 20-25mm pitch, and use a belt reduction from servo to ballscrew.

[joeavaerage]

Hi,

I'd go 20-25mm pitch, and use a belt reduction from servo to ballscrew.

Why? Use course pitch ballscrews only to then use a belt reduction on servos....complication for what gain?. If you used 5mm or 10mm pitch screws
you could direct connect them to servos. The high speed of the servos will ensure that you can still get decent rapids while the (somewhat) finer pitch allows
for high thrust and acceleration without the need for reduction.

My machine has 32mm diameter screws of 5mm pitch. At maximum tune I can get 25m/min rapids and 0.25g acceleration when direct coupled to 750W servos.
The combination means I have a stall thrust (without servo overload) of 3kN and at overload 9kN. Speed, thrust and acceleration....what's not to like?

Craig