Re: [CAD_CAM_EDM_DRO] Re: Z-Axis problem - Not Enough Torque?

Well .. not quite.
Stepper output power depends on rpm.
its most powerful at zero and decreases more-or-less linearly until it
hits a ramp,
usually around 800-1000 rpm.
The exact characteristics depend on your motor specs, and your psu
voltage, this issue has had many mails in thepast.

Anyway, the reults is that if you go to 10:1, and your max rpm is 800,
your max screw rpm is 80.

With a 20 mm rise, its still 1600 mm/min, or 64 inches, which should be
plenty good enough.
Many samller mills have rapids at this range. And You z-axis stiffness
and accuracy are improved !

Best,
Hannu


WT wrote:

>
> Hi Tony.
>
> If I can fit a pulley reduction of 10:1 as per your previous advise in my
> Z-axis, then my 4.2 Nm (almost 600 oz-in) stepper motor most possibly will
> be powerful enough.
>
> I have a further question and would like confirmation whether my math as
> follows are correct:
>
> Power = Torque x RPM (so, Torque = Power/RPM)
>
> If my Power is a constant (meaning, I apply the same voltage and current)
> and I make a belt/pulley reduction of 10:1, does that mean my Torque
> theoretical will be 10 times higher?
>
> Regards,
> WT
>
> ----- Original Message -----
> From: Tony Jeffree
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> <mailto:CAD_CAM_EDM_DRO%40yahoogroups.com>
> Sent: Wednesday, November 08, 2006 11:17 PM
> Subject: Re: [CAD_CAM_EDM_DRO] Re: Z-Axis problem - Not Enough Torque?
>
> At 15:01 08/11/2006, you wrote:
> >I think
> >the stepper motors may have enough power to drive the X and Y axis. Z
> axis
> >stepper motor may be a suspect.
>
> I think you will find that with the right leadscrew pitch (or if you
> use a reduction drive with the existing screws) those motors will be
> plenty powerful enough for all 3 axes.
>
> Regards,
> Tony
>
>