¶ Issue Description
After bed leveling is completed, the distance between the nozzle and the heated bed remains either too small or too large, resulting in poor first-layer print quality.
¶ Possible Causes
- The POM wheels are overtightened.
- The screws securing the brass lead screw nuts are overtightened.
- There is play in the X-axis or Y-axis.
- The X-axis gantry is not parallel to the heated bed.
- The proximity sensor is tilted or its connector is loose.
- Thermal drift is affecting the proximity sensor readings.
¶ Tools Required
- Open-end wrench
- 2.0 mm hex key
- Ruler
- One sheet of A4 paper
¶ Precautions
Before inspecting mechanical components or electrical connectors, turn off the printer and unplug the power cable.
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¶ Troubleshooting Steps
¶ 1. Check the Print Head and Heated Bed for Play
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Gently move the print head and heated bed by hand. Check whether either component wobbles.
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If there is play in the X-axis or Y-axis, use an open-end wrench to adjust the corresponding eccentric nuts.
Turn each eccentric nut by approximately one-third of a turn at a time. Several adjustments may be required.
Do not overtighten the eccentric nuts. The print head and heated bed should move smoothly without noticeable play.
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If you are using a Neptune 4 Pro, refer to the following guides to adjust the X-axis or Y-axis bearing tension:
X-Axis Bearing Adjustment
Y-Axis Bearing Adjustment
¶ 2. Check the X-Axis POM Wheels
Use an open-end wrench to turn the eccentric nut at the marked position to tighten or loosen the POM wheels.
Adjust the nut by approximately one-third of a turn at a time. Several adjustments may be required.
The POM wheels should remain in firm contact with the aluminum extrusion while allowing the X-axis assembly to move smoothly.
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¶ 3. Check the Screws Securing the Brass Lead Screw Nuts
The screws securing the brass lead screw nuts must remain slightly loose and must not be fully tightened.
Overtightening these screws may cause the Z-axis to bind or move unevenly. The condition shown in the following image is normal.
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¶ 4. Make Sure the X-Axis Gantry Is Parallel to the Heated Bed
Check whether the X-axis gantry is parallel to the heated bed.
If the difference cannot be determined visually, use a ruler to measure the distance from each end of the X-axis gantry to the heated bed. Compare the two measurements.
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If the X-axis gantry is not parallel to the heated bed, follow the video below to adjust it. The adjustment procedure is the same for Neptune-series printers.
¶ 5. Check the Proximity Sensor
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Turn off the printer and unplug the power cable.
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Refer to 00:00–00:40 of the following video to remove the print head:
https://www.youtube.com/watch?v=1y4ZUDKR2CY
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Check whether the proximity sensor connector is loose. Disconnect and firmly reconnect connector ①.
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Check whether the proximity sensor is tilted and whether the mounting screw ② is loose.
Make sure the proximity sensor is correctly aligned and securely mounted.
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¶ 6. Perform Manual Bed Leveling Again
- Follow the guide below to perform manual bed leveling again. The adjustment procedure is the same for Neptune 4-series printers.
https://www.youtube.com/watch?v=H6_7zMqcaMQ
- If the first-layer print quality is still unsatisfactory after manual bed leveling, follow the video below for further adjustment:
https://www.youtube.com/watch?v=p3taqQQ3qzs
¶ 7. Preheat the Heated Bed
Thermal drift may affect the detection accuracy of the proximity sensor.
Set the heated bed temperature to 60°C and allow the bed to preheat for approximately 20 minutes.
After the heated bed has stabilized, perform automatic bed leveling again and recalibrate the Z offset.
¶ If the Issue Persists
If the issue is still not resolved after completing the steps above, contact ELEGOO Technical Support at 3dp@elegoo.com and provide the following information:
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Printer serial number: Located on the white label on the lower-left underside of the heated bed. The serial number is usually formatted as
NEP4 XXXX XXXX. -
Current firmware version: On the touchscreen, go to Settings > About Printer.
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Results of the following checks:
- Whether the X-axis POM wheels were overtightened
- Whether the screws securing the brass lead screw nuts were loosened appropriately
- Whether there was play in the X-axis or Y-axis
- Whether the X-axis gantry was parallel to the heated bed
- Whether the proximity sensor was tilted or loose
- Whether preheating the heated bed improved the issue
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