Quote Originally Posted by JAZZCNC View Post
Agree with what jonathan says just one thing to point out 2:1 10mm pitch is effectivley 20mm pitch. If you can live with this loss of resolution then it's a good way to go.

What's your main intended use.?
5mm, 10mm .. . it all depends on what motor is driving the screw. If it's a 3nm motor then clearly a different ratio will be optimal when compared to using a 1nm motor.
If you're using it for PCBs then you'll want good resolution, so probably best to use swappable 1:2 pulleys. Can't really thing of anything else that would require it. Maybe engraving, but generally for engraving it's relative position that matters more than absolute which means microstepping is more valuable.