Quote Originally Posted by JAZZCNC View Post
Not really the relay contacts because it's a NO relay and when signal drops power to relay coils the contacts break naturally ( Unless faulty in which case it won't stop anyway.!)
It's the control software or more accurate the signal state you can't trust and in extreme case's it's possible it could switch state thru noise interference.!!
Exactly, I realise the relay contacts in play will be NO ...but it's the software/circuit that drives the coil I worry about...this is why I figured some condition dependent time delay would be brought into play here on the relay circuit ...therefore if a transient occured (in software or the control board), the spindle wouldn't kick into life straight away ...ultimately, I kinda seek a beep-beep-beep (like bin truck reversing sound), a couple of seconds before the spindle starts ...that way if I hear beep-age, I know to get my hands off the spindle sharpish!