writes:

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.

If they were really "tachometers", not digital quadrature encoders, then
you are correct that they would have been no use with Geckos. Tachometers
are common in speed-control (not position control) applications.

See my page on retrofitting encoders onto PM DC motors:

http://www.truetex.com/servomod.htm

And the resulting CNC motors onto a mill-drill:

http://www.truetex.com/ymount.htm

The best crude measure of "mystery motors" is often the shaft diameter. At
5/8", they must be pretty hefty units, perhaps 1/3 or 1/2 HP continuous.
At label rating of 50 VDC (which you won't want to exceed by much, this
probably characterizes the insulation quality), you might be looking at 5
to 10 amps continuous current under load, and several times that for short
periods.

If you want to get a detailed characterization, you need to be able to
measure speed, torque, voltage, and current. Then you can know everything.
Those can be measured with middling digital VOM, except for torque, which
requires some kind of dynamometer. Improvising a dynamometer has been a
project I've been musing about for some time.

Richard Kinch
Palm Beach County, Florida USA
http://www.truetex.com