Ignoramus7337 fired this volley in
:

what if due to whatever screwup of my adaptor
manufacturing process, the optical disc is more misaligned than the
specification permits, and thus would not count as well.


If your grating is misaligned with the two pickups, you'd likely get a
skipped count on every revolution, at any speed.

Did you make the pickup head adjustable? Is the grating centered well on
the shaft?

If the grating is centered and the head adjustable, you can do the
"standard" limit-to-limit kind of adjustment on it, then split the
difference, and you should be fine.

If not, spin the thing up to max (like you said you'd do), run it for a
while, then stop it, index it, and tally up the counts.

My bet is, if it's working reliably at 500 rpm, it'll probably be fine at
4K.

LLoyd