On Jul 13, 4:47*pm, Ignoramus3537
wrote:
....
I am afraid that if I allow slop in mounting of the reader head, then
if I accidentally knock the encoder, it will become misaligned. The
mount that I already made and used, has no "play" in head mounting, so
an accidental bump would not change any alignment.
i

Have you heard of toolmakers' buttons? I haven't seen new ones for
sale but they aren't hard to make, drill the center of some ground
drill rod and part off a few rings.

To use them drill your mounting pattern to scribed or worn-leadscrew
accuracy for an undersized tap, attach the rings with screws and
washers and knock them into position as measured with calipers or a
micrometer. Center each one under the spindle with an indicator and
bore out the threads, then drill/bore/ream to finished size.

This means you have to buy a small enough boring bar. The standard tap
was #5-40, which is 1/8" OD, and my B&S buttons are 0.200 in diameter.

I put a ground rod in the drill chuck and measure from it to a plug in
other holes.

I haven't tried this but if you have X and Y zero references like a
vise stop and the back vise jaw or a protruding parallel maybe you
could locate the spindle with an edge finder and the depth rod of
calipers. This would be a good use for vernier calipers that lie flat
face down.

jsw