Re: [CAD_CAM_EDM_DRO] Unknown servo motor specs

David Micklethwaite wrote:

> I have a couple of servo motors that I need to know more about before I try
> to use them on a medium size mill I am trying to convert to CNC:
>
> 1. Label says "AMETEK, 40 V DC and some meaningless part numbers". The case
> is 4" dia and 5" long with a 5/8" shaft at one end. The motor has two
> brushes. How do I fugure out the maximum current for this motor? I would
> have to drill the "back end" of the motor shaft to mount an encoder - is
> this a reasonable thing to attempt?

It is hard to say. Most motor manufacturers have several winding options
that allow a different number of turns to be in the field. So, some motors have
lots of wires that allows a lot of torque at low speed, others have fewer turns
of heavier wire, allowing modest torque and higher speeds, or operation from
lower voltages. If you have a torque rating (continuous or peak) you can
figure out the peak current. There may be some reference to this motor on
one of the surplus dealers web site, so you might do a search on the "meaningless"
part #.

Drilling and extending the rear shaft is pretty tricky, as you have to maintain
the center of the shaft pretty well, or the encoder will not work well.

> 2. Label says "Electro Craft Permanent Magnet Servo Motor". The case is
> 3.25" dia and 5" long. The motor has a 1/2" shaft at one end and a 1/4"
> shaft at the other which has a small electro mechanical clutch or brake on
> it. The motor has two brushes. There is no indication of voltage or current
> on this motor so how do I figure out what it can take?

If this has a part #, I can try to look it up in some old Electro-Craft books
I have.

Jon