Denford Software & Machines

Just after a little help . i have a triac on mach3 . i want to fit an rpm sensor to the spindle . i need to know what to buy and from where . i have a drawer full of dc6-36v proximity switches pnp ,npn ,no,nc . will one of these work . i was thinking of an opto sensor and a slotted disc type arrangement.

i will also do the same sort of thing for my mach 3 lathe


Any help will be appreciated .