Mounting a Speed Sensor on a BP step pulley mill

[titchener]

I'd like to put a spindle speed sensor on my BP clone step pulley
CNC retrofitted mill. I've been staring at it and haven't been struck with a bolt of lightening on a clean way to do this, its pretty tight in the housing
where the spindle pulley is, and the pulley moves up and down when you
go in and out of backgear.

Has anybody come up with a clean way to add a spindle speed sensor to
this mill type?

Thanks,

Paul T.

[awemawson]

If you use an inductive sensor of the type that is a coil of wire wrapped round a magnet, all you need is any discontinuity on the shaft or gears to sense rotation.
See:

http://www.corsa-inst.com/sensors/ss5.html

AWEM