On 2010-06-09, Karl Townsend wrote:


I am reading the drive datasheet right now.

The drive does accept the tachometer signal.

Also, I do think that the object that I showed on the picture, is
actually a tachometer. The wires are too small for carrying motor
power.

I received Jon's PPMC today and I will try to hook it up to the PC
(but not to the mill yet).

You won't need a tach input on the drive.

A servo is just a dc motor. Put the leads on your battery charger. It
should turn slowly.

Ignoring AC servo motors, of course.

A DC servo is A DC motor with a special design low-inertia rotor
(usually the windings in air, bound with epoxy or something similar)
with all the iron stationary to allow maximum acceleration.

Many of them have current limits which if exceeded will at least
partially demagnetize the permanent magnets making the field in the
motors. (Only the newest ones with rare-earth magnets, or those with a
DC field winding.)

The benefit of the tach feedback is the ability to run at a very
stable and very slow speed -- so you can move one axis very slowly while
the other moves at a proper cutting speed to generate a very shallow
angle ramp.

Enjoy,
DoN.

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