Re: microstepping torque

Hi Jon,

I use indeed pretty big steppers maximun holding torque is something
like 8.5 Nm, there also hybrid steppers. I don't know the diffenence
between hybrid and normal, but the curve (speed vs torque) of hybrid
steppers are more stretcht out, so they have more torque at high
speed. I have them run at 50.000 Hz, so that 1500 rpm, I use this for
rapid feed only.
All this is, as you mentioned, holding torque. Thanks for your
feedback.

Hugo




steppers --- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:

>
>
> 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