"Jim Stewart" wrote in message
...
Jim Wilkins wrote:
On Jul 13, 4:47 pm,
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.

Somewhere in my dusty library, I have a book that
takes your procedure one step further. It described
methods for making tooling fixtures for manufacturing
timepieces. X and Y were located by stacking Jo-blocks
between stops and the tooling fixture.

The old guys were pretty clever.

It may be one of Dick Moore's early books, which I think covered the
subject. When I first inherited my lathe, I spent the first three or four
months learning old toolmaking techniques, especially the use of the
faceplate and toolmaker's buttons (I have four faceplates and two sets of
Starrett toolmaker's buttons.) I even learned how to crush diamond bort and
make my own internal grinding tools. It's interesting to learn but I don't
recommend doing it. g

I still find it to be the most interesting part of old-time machining.
Around 1900, they could make master watch and clock plates (the ultimate
drill jigs) to +/- 50 millionths accuracy -- in plain-bearing lathes.

Moore's Jig Borer was the next step in the process of applying technology to
this fundamental problem. (NC milling was the next.) At that time (1900 -
1940), the dominant product of toolmaking was drill jigs.

--
Ed Huntress