X-axis layer shifting is a type of print failure where a model’s layers are displaced left or right on the build platform during the print. This distortion only happens along the X-axis and affects all models in the print job equally.

The Light Processing Unit, or LPU, in a Form 3 generation printer holds the laser that is responsible for curing resin during a print. The LPU rides left and right along the X-axis lead screw, underneath the resin tank. Over time, the anti-backlash (ABL) nut on the X-axis lead screw can degrade and leave a black residue in the grease on the lead screw. This debris can cause the LPU housing to stall or generate noise during printing. This stalling leads to layer shifts: the printer continues to operate normally with the LPU misaligned, activating the layer at the wrong location.

X-axis layer shifts can produce a variety of results:

• Sometimes models shift only once. In this case, the whole model starts printing to the left or the right of the previous layer.
• If there are multiple shifts, you’ll see different sets of layers built in the wrong spot along the X-axis. If the shifts are severe enough, the printed model might hang over the edge of the build platform. PreForm does not allow you to position parts this way, so this is a clear sign of layer shifts.
• Shifts can also occur while the raft is printing, before the supports or before the model itself.

Depending on your models’ geometry and the severity of the shifts, this may cause your print to fail because the shifted layers are no longer sufficiently supported by the rest of the part.

• Model shifts left or right on the build platform mid-print
• Poor layer registration
• Part of model hangs off the edge of the build platform

• Stripped ABL nut
• Contamination on the X-axis screw
• LPU calibration issue

1. Check that the shift is only happening along the printer’s X-axis (i.e., to the left or right). Shifts along the Y-axis or dimensional inaccuracy along the Z-axis have different causes and troubleshooting steps.
2. Clean and lubricate the printer's X-axis lead screw. A cleaning and lubrication kit is available for purchase on the Formlabs Store.
3. If the layer shifting persists, retry the cleaning and re-lubrication procedure.
4. If the lead screw cannot be adequately cleaned or layer shifting persists after multiple cleanings, replace the X-axis motor assembly. The part is available for purchase on the Formlabs Store. Follow the instructions in the guide Replacing the X-axis motor assembly (Form 3).

If the troubleshooting steps above do not resolve the print failure, contact Formlabs Support or your authorized reseller.

To help us provide the fastest and most effective response to your issue, please provide the following information:

1. Upload diagnostic logs.
2. Serial name of the printer
• The serial name is on the back panel of the printer in the format AdjectiveAnimal.
• Tap the printer icon on the Home screen.
3. Troubleshooting steps attempted
• Example: “I reoriented the model in PreForm. I inspected the resin tank and did not notice any damage, clouding, or debris.”
4. Resin formulation and lot number
• The lot number is inside the skirt of the resin cartridge.
5. Layer thickness
• Tap Queue on the Home screen. The Queue screen appears.
6. Relevant FORM files
• If available, attach FORM files of the model to the support request.
7. Previous attempts to print the part and any successful prints
• Example: “I printed the file part2.form three times previously. The first and second were successful. The third one failed.”