Re: Stepper size recomendation.....

Thanks Jan,

I was kidding about the nema 17s - I just pulled four of em out of
some old printers. They are cut little things, might find a use for
them somewhere, but not on this lathe.

I will be using ball screws, and depending on the pitch, I will work
out the best belt drive ratio for speed and torque on this little
machine. When I was teaching CNC, one of my customers had some PC
Turn 50 machines from Emco Maier that were I believe the original 9
x 20 machines (the iron part, not the CNC part).

Any way, those machine didn't really have enough power to cut steel,
even aluminum was a bit of trouble at times. It's been a long time
since I have seen those machines, but I believe they probably had
Nema 23s on them.

Based on the stepper suggestions you offered, it looks as though I
should be looking in the 300 Oz in range?

Thanks for the input.

Chris

--- In CAD_CAM_EDM_DRO@yahoogroups.com, JanRwl@A... wrote:
> In a message dated 3/14/2005 3:53:23 P.M. Central Standard Time,
> lcdpublishing@y... 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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