Is this theory about leadscrew pitch and stepper torque correct?

[phantomcow2]

Alright from what I understand, a stepper motor has the most torque at lower speeds.
Well my stock HF micro mill has ACME screws with a fine pitch, .050 per revolution. So obviously it would require the stepper motor turning it to spin at a higher RPM to achieve faster Rapids or cutting speeds. So i was thinking, what if I put something with say a .200 or even .5 pitch. Like one of those Kerk motion leadscrews.
Then wouldnt the motor have to spin at a lower RPM to achieve the same movement as the .050 stock screw? And this would mean it has higher torque, which nobody complains about. Also i would think rapids would be faster, not that it matters a hell of a lot for a small mill like mne, buts it cool anywys.
I was thinking about buying a leadscrew like the one here on ebay
http://cgi.ebay.com/ws/eBayISAPI.dll...e=STRK:MEWA:IT

Are all of my assumptions correct? Would i be making a mistake if I went ahead with a leadscrew like the one shown on ebay, am i overlooking some fact?

[ger21]

Your'e theory is correct, but can be tricky. A screw with a .05 lead will provide 10x more force than a screw with a .5 lead. Spinning the motor 10x faster is not necessarily 1/10th the torque. You also lose resolution with the higher lead screw, especially a .5 lead.

[phantomcow2]

Yea the resolution is a worry, my motors are 400steps per revolution but still...
So maybe i would be better off with a .200 lead

[ViperTX]

Also that lead screw on ebay has plastic nuts.....

[phantomcow2]

WEll do you know of any good online stores for leadscrews? I see McMaster Carr, but i like to have other options