Good evening collective wisdom...

I have a "toptech" 6x26 mill. (same factory as optimum)

I want to install a tacho on the spindle, but not sure exactly where it could fit.

This is a photo of the top of the spindle.

Firstly, I noticed today that there are 2 notches in the lock ring (?), and 2 screws which look like they maybe should be in the notches, but aren't....
Can anyone confirm? If so, should I loosen the ring to align, or tighten?

I wondered if I could make an aluminium bracket attached via one of those screws to hold the hall effect sensor magnet past the belt? I'm assuming I would need to make one for each side to keep whatever balance there is.

(the black and white pattern was an earlier attempt, using an optical sensor ex printer with a frequency meter - 60 pulses per rev results in the frequency being rpm. It wasnt 100% successful)


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