Homing problems and false endstop stops
The printer won't home, stops short of the end of an axis, grinds against the end, or halts mid-print saying an endstop was hit.
Also described as homing failed, won't home, homing error, endstop not working, endstop hit, grinding at end of axis, stops before home
Try these in order
Most likely and quickest to check first. Change one thing at a time so you know what fixed it.
Endstop switch or cable loose or broken
- Send M119 with the switch released and again while holding it pressed. It should change between open and TRIGGERED.
- Reseat the plug at both ends and check the wire isn't broken where it bends.
Interference from the motor wires
Endstop wires bundled tightly with stepper motor wires can pick up electrical noise that looks like the switch being pressed, so the printer stops early or halts mid-print.
- Route the endstop wires away from the motor wires where you can.
- Use twisted or shielded cable for the endstops.
- Turn on endstop noise filtering in the firmware if it has it.
Sensorless homing set too sensitive or not sensitive enough
Printers without endstop switches detect the motor stalling at the end of the axis instead.
- Adjust the stall sensitivity (StallGuard threshold) in small steps until it stops cleanly at the end without stopping early or grinding.
Something stopping the axis reaching the switch
- Move the axis by hand with the printer off and check nothing blocks it before it reaches the switch, such as a cable, clip or bent switch arm.