Ballscrew installation issues

stratton@... Wrote:

Subject: Ballscrew installation issues

>My plans for lathe conversion are

progressing. snip...

>What size (series/pitch) timing belts

are people typically using?

.2 pitch x 3/8 XL belts w/ 60 tooth
steel & polycarbonate pulleys 1:1
Berg and Stock Drive show more variety
than McMaster-Carr, but the prices
aren't listed in the catalogs.

>With a .200 lead screw and a 200 step/r

motor I need 2:1 reduction
just to get steps of .001, but am
planning on going for .0005 or
.00033 if I use a 10 tooth driving a 60
tooth.

You may well end up using a half step
driver for increased torque and reduced
resonance reasons.
A 200 step per rev motor is 400 discrete
half steps per rev.
Also note the McMaster 5/8 screws are
31/64" pitch; with 1:1 drive, I
calculate: 1.8 deg per step motors, 200
steps per rev, 400 steps per rev half
step mode;
13/64" screw lead =(.203125 inch per
rev, or 4.9230769 rev per inch)
So: .203125 / 400 = ~1969(.2792) steps
per inch for ~.0005 resolution.

Am I in some kind of trouble with this
odd number (vs 2000)?
I know CNCPro can't use the decimal
remainder (.2792) on steps per rev
setting.
I didn't want to gear it down and lose
the travel speed potential or, God
forbid, lose steps by trying to spin the
motors too fast...