Re: [CAD_CAM_EDM_DRO] microstepping torque

hugo_cnc wrote:

>Hi all,
>
>I've a question about microstepping. If I look at the speed vs.
>torque diagram, the steppers I'm using have a torque of 3 Nm (460
>0z/in) at 5000 Hz. This in half step mode, if use microsteppers what
>happens with the torque.
>With microsteppers I use 5 times more steps for the same revolution,
>so at 5000hz the microsteppersriver is sending 25.000 steps. The
>torque at 25.000 Hz is pretty low.
>So basicly the questions is how does microstepping inflect the torque?
>
>

Microstepping should not affect the torque. Have you actually observed 3
Nm at 5000 half-steps
per second? I would be very suspicious of this measurement. In general,
most steppers lose a
great deal of their holding torque even at moderate speed. 5000
half-steps/sec (where half-steps
give 400 pulses/rev) comes out to 12.5 Rev/sec, or 750 RPM. That is
going pretty fast for
large, two-phase steppers. If they really give 3 Nm at this speed, they
must have holding torque
of nearly 10 Nm, I'd guess. (5-phase steppers do much better in this
regard, though.)

I wonder if this "spec" is really a typo, and the meaning was supposed
to be that you get
3 Nm HOLDING torque, and "usable" torque to 5000 half-steps/sec.

Jon