Stop machine if spindle motor fails.

I have built a cnc with axis driven by stepper motors,the spindle is driven by a DC motor.I want to know how to stop the machine running if the spindle motor stops,Do I need to put a speed sensor on the motor shaft,if so how do I wire it up.?Eric

erkiwi,

Assuming you are using Mach3,

Hardware wise it would require a sensor to provide a index pulse and an available input port.

A custom macro would then be required in order to monitor lack of spindle motion while there is g code program activity and initiate a eStop.

Jeff...

Thanks for your help...Eric