Re: [CAD_CAM_EDM_DRO] Spindle Encoder resolution

Dennis Fielder wrote:

> Jon Elson wrote:
>
> > Now, with a spindle encoder
> > of 200 cycles/rev, that gives 800 (real, not pseudo)
> counts/revolution.
>
> My only reason for the pseudo is that I understand the encoder output
> edges, since they come from 2
> sensors and different detection directions, are not necessarily as
> uniform as one edge from one
> sensor. So the accuracy of the encoder may be worse when this is tried
> (but then again, might not be
> significantly worse).

This is true, but the accuracy of so many other things are causing
trouble when you get down
to the .001" and below scale, that it is not a big deal on standard
machine tools. There is
backlash, even on ballscrews, there is flex in the mechanical mounting
of the screws and
nuts, bowing of the leadscrew, rocking of the slides, etc. many of
these things cause
more error in the very small ranges than over large moves.

> > What I'm trying to point out here is that the resolution of the Z
> axis
> > (stepper or servo/encoder) will be dominant most of the time, not
> the
> > spindle encoder.

Well, depending on what you make, it could be the Z or the X, but yes,
for threading
operations, the Z axis will be dominant.

Jon