leadscrew pitch help

[Speedy]

have to figure out what pitch I want for leadscrews on my sherline as it will be cnc.

any advise on this?

 

[Tin Falcon]

What choices so you have. are you modifying one or purchasing new.

most cnc stuff uses ball screws. if it is a choise of metric or sae does not matter a lot. More important than style or flavor is a good consistent quality screw. then the computer will do the math and make things happen . an inconsistent lead screw will give inconsistent results.
Tin

 

[kf2qd]

The finer the pitch, the more force you get for moving the slide, but the finer the pitch, the weaker the ball screw because of the small size of the balls and grooves. A finer pitch means you need less motor to move the axis. You probably don't have to worry about the strength of the ball screws though, when you consider the siz of the machine you are putting it on.

A rule of thumb - get the largest diameter that you can put in your slides, that would give you more strength and accuracy for a given pitch.

 

[Tin Falcon]

When I converted my little 5" lathe to cnc I just used the factory feed screw.
http://www.homemodelenginemachinist.com/f38/little-cnc-lathe-7750/
Tin

 

[andjuh]

Hi
I have converted several machines (siege x2) for cnc machine and selected ball screw with 4 mm pitch for step motor with half steps (400 steps / revolution) gives 0.01 mm / step, it gives good accuracy and easy to work with if you want to move the table 14:22 mm then the 1422 steps