Eddy,
what is this one: *spindle over temperature switch activated ?

Where did you find a cheap temperature sensor with digital display that has a contactor or signal at programmed temperature?

I have bought a cheap 7eur battery one with temperature alarm, and thought of using the alarm output ~3v to connect to the BOB, but forgot about this project.

Once i accidentally switched off the water pump and spindle worked all day before i touched it and saw it was hot. Nothing happened. Still works. Though was just V carving.