In article ,
wrote:
Hi people,

At the local trash and treasure I spotted two 50v DC motors with 12g
red and black wires. Bought the pair for $8, so no great loss if they
are not useful. However, if I can find some more specs I am hoping
these, encodeers and some gecko drives will be the X-Y part of a
plasma cutter table.

No encoders, but they had a flat-belt pulley that drove a 3" diameter
x 3" long tachometer. I let the guy keep the tachs. g

*That* was a mistake. If you're going to use these as servo
motors, you need speed feedback to the servo amps.

All they have marked is...

OIA
135-0043-001
50vdc nominal

They have 5/8" diameter shaft, body about 4" diameter and 7" long.

At 50vdc they draw 0.4A free running at 1300rpm.

They only have two brushes but 90-deg apart.

Interesting.

Also the current stays at 0.4A from about 32v to 50v. Below 32v the
current slowly drops but not by much. Even at 20v it is still about
0.35A. Not sure if that helps or not.

The current will go a lot higher when the motor is stalled, or
trying to start (or stop) a heavy object. No clues as to what is the
maximum current before the permanent magnet poles get demagnetized?
You'll need to determine this to set the current limit on the Gecko
driver -- or on whatever other servo amplifier you wind up using.

Anyone have an idea of what where and who's??

Mostly -- if you want to use them with speed control, you should
go back and get the tachs. A servo amp compares the voltage fed into it
as a command with the voltage from the tach, and controls the voltage
fed to the motor to produce the commanded speed.

I'm not sure what the Gecko drivers will do -- as most of their
drivers are for steppers, not servo motors, and only one (IIRC) is
intended to drive a servo motor.

In most uses, without the tach generator, it tends to overshoot,
and come back, and spend a lot of time just bouncing around the desired
point (called "hunting").

O.K. -- looking at the PDF manual file for the G340, it seems to
do without the tach feedback, and just use the encoder. But then, it is
making the servo motor pretend to be a stepper motor, so I guess that
what you have will work. But it *will* hunt -- which they describe as
"singing" in the manual.

Good Luck,
DoN.
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