RE: [CAD_CAM_EDM_DRO] Re: Plasma table gear reduction

I wanted to comment on servo heat issues running at low speeds and
high torques.

There is a spec called "maximum continuous stall current". If you stay
below that
you will be fine.

The servos I sold (sorry all out) are a good example. They are spec'ed at
about
5 amps max running or stalled, 8 running or stalled with external forced
air cooling,
and 26 for 1 second running or stalled.

This is typical, and in cnc tool applications usually the duty cycle is
low...
only corners, stops, and starts require large currents and then for only a
short time.
Machines with very tightly gibbed box ways might need a bit more due to the
extreme friction.

I realize that many surplus motors may have unknown specs, but you can run
tests.
With a locked rotor at a certain current (for several minutes)
you should be able to touch the housing without extreme discomfort.
If that is the case you will probably be fine even
with the higher internal winding temperature. This is quite consevative, as
many are
designed to be run VERY hot.

Les
Leslie M.Watts
L M Watts Furniture
Tiger Georgia
(706) 212-0242

Main page:
http://www.lmwatts.com
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