Re: [CAD_CAM_EDM_DRO] Re: How to determine Torque from these motor numbers?

Your motor is very similar to the Aerotech 1210 which I have specs for.
The size is the same. Nema 42 about 5" long. Terminal resistance is
1.8 Ohm. They spec Kt=35oz-in/A and 6A continuous or 210oz-in
continuous for this motor. I made the comment about the size of the
motor and even though they are the same size your motor makes 50% more
torque per amp. The max RPM they spec is 3000 so you should be safe
running your motor to 1500RPM.

I do have a question. How did you measure the RPM? If your motor has
rare earth magnets this would account for the difference between it and
the 1210. There really isn't any simple way to tell what type of magnet
is in the motor. If the RPM measurement is accurate then the numbers
everyone came up with are accurate.

Stalling the motor is OK. If you start with a very high current you
could overheat the armature before the outside of the motor gets hot, so
start low. I have done this to quite a few motors. As long as you don't
overheat it, it doesn't matter. There are basically two limits to
electric motor operation the amount of heat it can dissipate (the
current or torque limit) and the maximum RPM at which mechanical issues
limit the life of the motor (the RPM limit). Operating the motor within
those two limits is pretty safe. If you are trying to push the envelope
of both limits you can run into problems, basically as RPM increases
maximum current has to be derated.

As far as powerful, well they make a lot of torque. If you had a motor
with similar torque but it ran faster it would be more powerful (it
would also be larger). Or you could have a motor that made less torque
and ran faster it could make the same amount of power. I think the
motor will work just fine. They may be slow compared to some motors,
but if you run a 60V supply it shouldn't be an issue. With that much
torque you could run a higher pitch ballscrew to make the machine faster.

Greg


Earl wrote:

> Thanks for all the help and numbers so far yall. You dont know how
> much the helps out! :)
>
> these motors are around 4"D x 5"L in size.. I guess from what I'm
> hearing is that they are actaully more powerful than I thought?
>
> Lastly, Greg when you mention testing the motor for temperature
> buildup, Is it OK to let the motor cook at locked shaft.. even at (a
> low) 3.7A? just seems that cant be good on it for any length of
> time... but if thats what it takes! :)
>
> thanks again all-
> Colin