Re: Some servo motors on Ebay, usefull for CNC??

Jon Anderson wrote:

> From: Jon Anderson <janders@...>
>
> Here's a link to an auction on Ebay for some brand new Warner servo
> motors.
>
> http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=205968185
>
> The auction closed, but it was dutch, with 20 motors available, none
> sold. Can anyone reference these and tell me if they would be good for
> CNC'ing a knee mill?

Hard to say. Looks like they have an optical encoder (the DB-9 connector)
and the nameplate lists the Ke as 25.15. So, the motor needs 25 V to
turn at 1000 RPM, and 50 V to do 2000. That is in the right range.
4.84 A continuous also sounds good, but it is a little hard to compute
torque from that. But, you can get a rough idea. 4.8A x 50 V = 240 W =
~ .3 Hp. No indication of the peak rating, but it should be twice the
4.84 A, at least. You can compute the torque from the Hp guesstimate,
but I forget the constants off the top of my head. Anyway, these are
stronger than my motors, which drive a Bridgeport pretty well (with
ballscrews). I have a 2.5:1 belt reduction from my motors to the 5 TPI
screws. These could probably drive a screw directly, but that might be
a little close to the edge, unless the peak current is way above 5 A, which
it could be. These motors would almost certainly do fine with a belt
reduction, but then you put the belt & pulley errors inside the error
from encoder to leadscrew.

>
> I got some Glentek servo amps off ebay recently, viewable at:

Yes, if these are designed for DC brush servo motors, they should be fine.
Those look like old servo amps, they probably need a DC tach for velocity
feedback.

Jon