Re: Step motor torque

--- In CAD_CAM_EDM_DRO@egroups.com, Joe Vicars <jvicars@c...> wrote:

> Has anybody taken a good look at the torque curves provided on

the

> Microkinetics web site for their stepper motors?

Yes.

> For their 34M470 (big NEMA 34) the rated holding torque is 460

oz*in

> but the torque curve shows better than 500 up to about 300 rpm.

It is common for motors to show some dips and
bumps in the torque curve at lower speeds. This
can be caused by electrical resonances in the
driver or motor at certain frequencies, even
mains ripple on the supply dc. Some motors also
have a slight torque gain at low speeds, higher
than holding torque.

> On the other hand, the 42M1150 which has holding torque rated at
> 1125 oz*in never gets above 525 oz*in at any speed according to

their

> curves.
> This is assuming both are running on the 72V supply. What's the
> deal, is this a typo?

Hmm? But it seems to be an error. Either the dyno
device tops out at 500oz, or their psu/driver,
etc but something there has topped out. With a
large motor the holding torque will be huge
but torque will drop very quickly once the motor
speeds up.
-Roman