Many thanks for the explanation, this switch seems rather small, the spec sheet says it has a gap of only 3 mm, therefore i would need a piece of metal less than 3 mm thick to go through it, would this not be a bit flimsy for a robust milling machine? and also would this switch be ok powered by my ZP5A Breakout Board, which only gives out 5 volts? and does it wire directly to the BoB?

Ray
Quote Originally Posted by Clive S View Post
Yes its an optical switch that is to say an invisible beam of light it being shone across the gap in the sensor and then when use pass a piece of dark plastic or metal into the gap it breaks the beam and triggers. ..Clive