Quote Originally Posted by andy_con View Post
How do people estop these water-cooled spindles?
You can use one of the VFD inputs and program it as an e-stop, but when properly connected to the controller when the E-stop has been pushed the controller should shut down it's outputs which will in turn stop the RUN signal.

Also on a properly built machine, the E-stop will be hard wired to some relays which will physically disconnect the run signals rather than rely on just software to stop the machine.