re:Extra Small stepper motors

Gordon wrote:

>I'm trying to shoehorn a lathe slide/compound unit onto a small
>lathe. I'd like to be able to control this via CNC. Anyone know of
>some really small stepper motors I can use for this? A source for
>purchase as well as design dimensions would help as well.

Smoke,

For small diameter bodies, the 'hybrid' stepper type will be better
than the 'pancake' style motors...

Hybrid steppers (another name for what we on this list commonly mean
when we talk about steppers) come in several sizes which roughly
relate to body diameter/ Faceplate size. The typical range is 11
(about 1.1 inches diameter),17 (1.7 inches), 23 (2.3 inches, commonly
used for sherline retrofits), 34 (3.4 inches), 42 (4.2 inches,
typically used on bridgeport and BP retrofits).

These sizes also come in different lengths (within each size) which
correspond to the internal iron core makeup, and are thus referred to
as 'stacks'. As in a 34, single stack motor; 23 triple stack motor.
One to three stacks is common, but I personally have not seen double
or triple stacks in the smaller sizes you may need.

From a reply post, it appears that a size 11 may fit. I don't think
you will be able to generate the torque needed for any sort
of 'cutting' movement from this size STEPPER. A high TPI may help
some. MAY BE ok for 'positioning' and then "lock" the compound with a
solenoid... BUT,

A SERVO motor in this size will probably be a much better choice, at
the expense of some control complexity... 1 inch diameter servo
motors can be had with higher REAL torque than steppers of similar
size.

Hope this helps.

Ballendo