¶ Fault Symptom:
During Z-axis homing, the nozzle continues to descend without stopping.
¶ Possible Causes:
- PEI build plate is not installed
- Proximity sensor is tilted and cannot detect the PEI plate
- Nozzle is not installed correctly
- X-axis is tilted
- Proximity sensor is faulty
¶ Tools Required for Troubleshooting:
- 2.0mm hex screwdriver
- Wrench
¶ Troubleshooting Steps:
¶ 1. Confirm the default PEI build plate is installed and its material meets requirements
a. The proximity sensor on the Neptune 3 series can only detect metal. Do not click Home, perform leveling, or start a print without installing the PEI build plate.
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b. If you are using a non-original PEI build plate, please ensure it is made of metal.
¶ 2. Check if the extruder is loose or tilted
a. Manually shake the extruder assembly and check whether it wobbles.
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b. If the extruder wobbles, tighten the eccentric nuts at the marked positions.
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¶ 3. Check whether the nozzle is installed correctly
The proximity sensor on the Neptune 3 Pro series has a detection distance of 4mm. If the nozzle protrudes too far due to incorrect installation, it will interfere with the sensor during Z-axis homing.
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¶ 4. Check if the proximity sensor is loose or tilted
a. Turn off the printer power switch and unplug the power cord.
b. Disconnect the cable.
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c. Remove the screws securing the extruder and take off the extruder assembly.
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d. Check whether the screws fixing the proximity sensor are loose.
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Reminder: The detection part of the proximity sensor must remain parallel to the build plate. If the sensor is tilted, it will fail to trigger properly.
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¶ 5. Check whether the X-axis is parallel to the build plate
a. Turn off the printer power switch and unplug the power cord.
b. Visually check if the X-axis is parallel to the build plate. If it is difficult to judge by eye, use a ruler to measure the distance from both ends of the X-axis to the build plate.
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Please refer to the following video to adjust the X-axis:
https://youtu.be/EselQDI0_28
- If the issue persists after completing steps 1–5, the proximity sensor is likely damaged and needs to be replaced.