On 2010-08-11, Ignoramus9618 wrote:
2. I would need to somehow mount a shaft to protrude upwards, from the
spindle, and to "fix it" inside the spindle. What is the best, proper,
etc way of doing so.

The encoder that I bought from US Digital has a optical wheel with ID
of 3/8".

I found a McMaster item 8795K351: Amber Polyurethane Tubing 1" OD X
3/8" ID, 2" Long, 80A Durometer. Supposed to be as hard as shoe heel.

If the spindle really is 26mm ID, I could easily put a 3/8" bolt or
threaded rod through it, put it inside the spindle, tighten it so that
the rubber tubing expands. Then it would decently grip the inside of
the spindle. And it would probably be centered well enough (0.01") to
hold the optical disk. Am I missing anything?

i

Ignoramus9618 wrote:

On 2010-08-11, Ignoramus9618 wrote:
2. I would need to somehow mount a shaft to protrude upwards, from the
spindle, and to "fix it" inside the spindle. What is the best, proper,
etc way of doing so.

The encoder that I bought from US Digital has a optical wheel with ID
of 3/8".

I found a McMaster item 8795K351: Amber Polyurethane Tubing 1" OD X
3/8" ID, 2" Long, 80A Durometer. Supposed to be as hard as shoe heel.

If the spindle really is 26mm ID, I could easily put a 3/8" bolt or
threaded rod through it, put it inside the spindle, tighten it so that
the rubber tubing expands. Then it would decently grip the inside of
the spindle. And it would probably be centered well enough (0.01") to
hold the optical disk. Am I missing anything?

i

That might work, but I would provide an upper bearing in your encoder
mounting plate as noted in my other post, to ensure the shaft remains
centered since wobble would tend to destroy the encoder.