CNC Machine Won’t Home — Causes and Fixes

Homing is your machine finding its reference point. Without it, the controller has no idea where any axis is. 

Most controls won’t let you run a single program until all axes have homed correctly. No home, no go. 

• Home limit switch failure — swarf and coolant wear these out over time. 

• Switch cam bent or knocked — the physical trigger for the switch has shifted. 

• Wiring fault — broken or loose connection. These can be maddeningly intermittent. 

• Servo drive fault — if the drive has an alarm, the axis won’t move at all. Check for drive alarms first. 

• Mechanical obstruction — something physically blocking the axis from reaching its home position. 

 

First question: does the axis actually move during the homing attempt? 

No movement at all = drive or electrical fault. Moves but stops in the wrong place = switch or cam issue. 

Most controllers have a diagnostics screen where you can watch switch inputs in real time. 

If the input doesn’t change state when the switch triggers, the switch or its wiring is your problem.