Re: re:OK - you convinced me - was "Automated "Manual CNC"

Thank you once again for the informative answer!

I am a little confused when you talk about backlash being a problem
in my proposed set up. In open-loop or closed-loop with position
feedback from the motor, I understand about backlash being a problem.
The PC has no way of knowing the true position of the workpiece due
to the backlash. However, with closed-loop with feedback from the
table, couldn't the CNC program just work around it?

I think in an earlier reply, someone said a piece of all-thread rod
could be used as a leadscrew as long as actual position feedback was
being used for closed-loop operation. Backlash and inaccuracies in
the feed mechanism should be compensated for by the program, right?
This should be similar to backlash compensation with stepper motors,
only more elegant and precise.

My encoders probably will be digital caliper heads running on
lengthened scales. Output would be through the SPC port. This is why
an interface circuit would have to be built to go from SPC output to
standard quad pulse output.