Re: Stepper controller / driver for powerfeed

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "David G. LeVine" <dlevine@...>
wrote:

>
> At 09:13 AM 10/1/2007, you wrote:
> >How are they lacking for a power feed unit? A DC motor will
> >precisely repeat the same speed in both directions. A stepper motor
> >is overly complicated for a power feed unit.
>
> DC motors with variable resistors or voltage feeds still do not hold
> constant speed with varying torques. The feed may change with load
> resulting in a poor finish.

How much variation in torque would you expect on a 9 x 12 lathe?

A slight slowing of speed during a facing operation( X axis) would be
perfect for a power feed. If the power feed was along the Z axis,
there would be little or no variation in torque. Hence it is a very
good solution for both lathe axes. That is probably the reason that
many power feeds are done with simple DC motors rather than steppers.
The KISS principle.

Fred Smith - IMService
http://www.cadcamcadcam.com