What's the right ballscrew pitch on a small home-built CNC mill or lathe?

Fellas,

Well, the goodies from the Bridgeport auction just keep on comin' at eBay. What a haul... I've never seen such a glut of new ballscrews in my life. And linear ways, etc. Blowing my mind and wallet this month.

The first load came in today, and I'm impressed. Three new-in-box ballscrews at ridiculously low prices I couldn't pass up, even though I don't know just exactly what I'm holding here. Try $120 for TWO new 30" NSK double-nut screws with a deviation test report. Insane, really... These screws are just beautiful.

Of course, I had little choice as far as lead pitch was concerned. The screws are solid and smooth, but I'm wondering if a 10mm lead is too steep for most stepper motor cnc applications? And one is 16mm, not even two threads per inch.

If anyone knows, what do most folks use out there, pitch-wise? I'm having a nightmare of these stout screws requiring a 600 oz.-in. servo motor to get 'em up and running right!

We are in the process of gathering parts to build a CNC router. The "Z" axis slide unit we bought has an .0909 pitch (11 threads per inch). We haven't bought the "X" or "Y" screws yet but are considering a lead screw with a .200 pitch (5 threads per inch). I, too, would be interested in hearing from others who have "been there" before making a final decision.

The newer ballscrews have a lot more aggressive pitch than older ones since linear guide rails allow much higher traverse rates. You can run high pitch screws at slow rates but you'll have to play some tuning games to keep hum and dither to a minimum when holding a position. If you are going to use steppers, just limit your step rate and you should be fine.