DRO Encoders

I've been following the discussion of linear encoders for a DRO. And have a
couple of questions again.....

(1). Why not use rotary encoders? They are very available and cheap. If my
math memory is correct Diameter * Pi = Circumfrence of a circle. So, a .318
diameter wheel gives a linear distance of .9990264786... per rotation. Using
a 1000 count per rev encoder results in a resolution of .0009990264..... If
that's not good enough, use a 2000 counts per rev. That's only another $7 or
so from US Digital. It's not that difficult to mount the rotary encoder on
the non moving base of each axis's slide.

(2) If #1 is not acceptable, why not use some of the el cheapo digital
calipers that have serial port output? Then feed the serial output to a PIC
and let the PIC display the 3 axis values on an LCD.


Larry Edington
larrye@...