Hi Guys: Had an issue with my ER16 collet spindle. My homebuilt machine would stop at random moments while doing a job. Found out from HobbyCNC that running the limit switch wires in the same bundle as the stepper motor wires can be a problem with more powerful spindles. Seems some stray voltage can be induced into the limit switch wires and stop the machine. Ran those wires away from each other and no more problems.