Re: Why is the push to such high step rates (Grex and Arc100)?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "lcdpublishing"
<lcdpublishing@...> wrote:

>
> So, once again, I am back where I started, is there a practical
> application?

Wire EDM and grinding are programmed in the 10 millionths of inches.
In order to attain process capability, machine resolution with at least
an order of magnetitude smaller than these divisions is needed. That
yields .000001 inch resolution ( one millionth ).

Threading is a good example of an application that benefits from high
speed and high resolution. Up to the max rpm of inexpensive encoders,
using a quadrature encoder for threading, improves the lead accuracy as
well as the range of available spindle rpms at which a given thread-
diameter combination can be machined. If you electronically gear the
spindle to an axis, the step rate of the axis is multiplied by the
available spindle speed and will quickly out strip a stepper. putting
a hi resolution encoder on the axis motor will provide a good balance
to the spindle encoder.

As you calculated, up to around 125000-135000 sps is about as fast as
is practical for hobby use. DeskCNC has been available at 125000 for a
couple of years. Very few hobby CNC applications challenge that rate.

Fred Smith - IMService
htp://www.imsrv.com