Re: [CAD_CAM_EDM_DRO] Any ideas for ID'ing this motor?

"Mr. sausage" wrote:

> Hi group,
>
> Just came back from a local industrial salvage yard. Picked up an olde
> mainframe computer tape drive - remember the ones with the large reels and
> vaccuum tape handlers? Well, I liberated the rather largish reel motors.
> They have no manufacturer named on them; they have some miscellaneous
> numbering and say "50 volts nominal". They are 7" long by 4" wide.
>
> Anyone seen this kind of motor before? Any idea what kind of current
> requirements these beasts have? Will they overload my Gecko 320s even
> though I have 5A slo-blo fuses connected to each?

These should be nearly ideal motors. Especially if they were used in
a direct-drive arrangement, where the reel hubs were mounted directly
on the motor shafts. In that configuration, the motors are wound for a
lower RPM and higher torque than the usual setup for these motors.
ie. they would be somewhere around 25 V/1000 RPM, rather than
the more common 10 V/1000 RPM on a 50 V DC motor.

These motors will not overload a servo amp, unless the shafts are locked.
As long as they can move, a servo amp will apply current up to the design
limit of the amp (or current limit setting) only during hard acceleration,
and
then current will drop to what is necessary to move the load. Obviously,
a Gecko drive can't move a 50-ton K&T mill table, but should have no
problem with a properly sized machine.

The one problem is that any permanent magnet motor can be damaged by
even momentary excess current. Fuses may not blow fast enough to
protect the motor, but that is a fairly extreme mishap that shouldn't be
too much of a worry. 5 A is almost certainly safe for a motor of this size.

These sound like the Ametek motors that everybody was selling about 2
years ago.

Jon