Alarm 15 is built into the firmware’s dual homing feature to prevent the left and right Y-axis motors from skewing the machine and causing serious damage.
Issue(s):
- Homing cycle cannot complete, getting Alarm 15: Homing fail. Could not find second limit switch for auto squared axis within search distances. Try increasing max travel, decreasing pull-off distance, or check wiring.
Resolution(s):
Usually this indicates that the Y-axes are not moving in alignment, so one side is moving farther than the other.
- Check that the couplers on both Y-axes are firmly secured
- Make sure the limit switches are bottoming out at the integrated bump stops, on both Y-axes
- Square up the Y-axes by jogging them all the way to the back, so they hard stop. Then try jogging forward and see if both sides are moving the same amount
- Check that the DIP switches on both Y motors are set correctly
- In Config, under Homing/Limits, turn OFF the setting Limit Jog Commands ($40). Press Apply Settings then turn OFF/ON the controller.
- If Limit Jog Commands is ON, jogging past the machine limits can trigger Alarm 15
- Specifically for AltMill MK1:
- Make sure the Y-axis motor and sensor cables are connected properly as pairs. The Y1 sensor cable must be attached to the white connector above the black Y1 motor connector. The same applies for Y2.
- Jog the machine to the rear bump stops of the machine, so that the right and left Y-axes are at the same Y position. Then check that the sensors on the left and right Y-axis are sticking out the same amount from their respective end plates. Now you can try to home again.