Re: [CAD_CAM_EDM_DRO] Stepper size recomendation.....

In a message dated 3/14/2005 3:53:23 P.M. Central Standard Time,
lcdpublishing@... writes:

So I am trying to determine the best size motors (in oz./in) I should be
looking for. My "More power" side of me wants to bolt on some 600 oz/in motors,
but my wallet says nema 17s ;-)<<
I assume you are JOSHING about "NEMA 17" for a 9x20! I would go for
something like the Superior Electric KML092-F07 Bipolar steppers, using GECKO 210
drives and a decently-built UN-regulated supply with about 70 volts UNloaded,
and capable of five amps load. The "chopper high-voltage" design is vastly
more efficient than the old "LR system" with energy-wasting power-resistors in
series with the motor's +common leads. OH: This kind of stepper is
commonly known as the new "Square NEMA 34, two-stack" size.

NEMA 23, even triple-stack, would be a bit shy for some work the 9x20 size
lathe can do.

Back in '99, before I knew about the Gecko drives, I built two lathes (see
photo: "Homebre...") using these motors and Superior Electric's proprietary
bipolar-chopper dual-drive with power-supply in one box, and that worked
very, very well. A similar lathe built in '84 used "round NEMA 34" unipolar
steppers, and it is sometimes "borderline" and can NOT be expected to display
"brute force". And it's DC motor-supply is 24 volt/15 amp.

I assume you realize you must (better!) replace the lead-screws with
preloaded ball-screws, or at least (second choice:) fine ACME screws with preloaded
Turcite nuts. If you leave the screws and nuts as-is from the manufacturer,
you MIGHT eliminate some backlash by tweaking the half-nut on the Z axis, but
for the X axis, you'd be kinda "on your own".

Lotsa luck! Jan Rowland








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