Thread: 6x26 mill questions

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)

Russ

I'm assuming I would need to make one for each side to keep whatever balance there is.

This suggests you are putting the sensor on a moving/rotating part?

My understanding is only a small magnet needs to be attached to any rotating parts and the sensor via a bracket is held in a stationary position ?

Just the magnet, above and outside the diameter of the Step pulley.
Mounting the sensor itself on the side of the belt cover probably.

Even though the magnet is small and I'll make the bracket from aluminium it could be spinning up to 2000rpm I guess..


Russ

Hi Russ, Guys,

A small magnet, say 3 mm square super glued somewhere on the edge where you have glued the paper strobe pattern and the hall sensor on an aluminium bracket will work just fine. There would be virtually no weight to worry about.

Actually the speed sensor on mine is a simple alloy disc with holes drilled in it and an optical slot detector to sense the holes as it goes past.

Those two screws are there to lock the adjustment nuts together they don't go into the slots.

The nuts are done up correctly. the slots in the lower one are for a tool to drive on to tighten it. The screws in the upper nut push on the lower nut, to stop it undoing.

Thanks for the confirmation guys.

I hadn't thought of just super glue for the magnet.
Might need to put a small packer below to make sure the sensor is clear of the drive belt.



Too easy..



Russ

Hi Russ,

I don't know if you are into salvaging stuff, but if you have a scrap hard disk drive you could salvage the head arm retaining magnet. There are a number of variations of these but the magnet could be anything from 2 mm diameter and 2 mm long, to square 3 mm and a mm or so thick.

Don't confuse the main magnets, they are much bigger and will happily take a bite out of your fingers ! Vicious things they are.

You used to be able to salvage the hall device on the very old 5" inch drives, but the modern ones are usually built into the motor and you cannot get at them. However an old 5" or 3.5" floppy drive usually has three and sometimes four that you can easily get at, and often a suitable magnet glued the the outside of the rotor.

Good hunting