Separated layers, cracks or delamination

Symptom

The part splits between layers, has horizontal cracks or layers peeling apart like sheets. Sometimes cured pieces float in the vat or large solid areas come out warped.

Likely causes, from most to least likely

1. Orientation, layout or supports leave sudden changes in area between layers or hanging areas, and the peel force pulls them apart.
2. Resin shrinks as it cures: in large solid layers that stress warps or separates layers.
3. There is dirt or cured debris in the vat, or the vat and its film are old.
4. The build plate is loose.
5. The print was paused for a long time, for example when the resin ran out, and the next layer does not bond well.
6. The model file is corrupted or, less often, the UV light is failing.

Checks to tell which one it is

• See where it splits: if it matches a sudden change in cross-section or an unsupported area, it is an orientation and support problem.
• Print a manufacturer's test model: if it comes out fine, check your file and settings; if it fails the same way, check the vat and the machine.
• Run a plastic scraper along the bottom of the vat and look at the film against the light.
• With the printer stopped, check that the build plate has no play.
• Remember whether the print paused or warned about low resin.

Before you start

Uncured resin irritates skin and eyes: wear nitrile gloves and safety glasses, ventilate the room and do not look at the UV light. Before taking anything apart or cleaning it, switch the printer off and unplug it, unless a step says otherwise. If in any doubt, stop and ask a professional.

Step-by-step fix

1. Try a manufacturer's model

   Print one of the pre-sliced samples that come with your printer or its software.

   Check: If the sample prints without separation, the machine is fine and the problem is in your model or your settings.

   If that does not fix it: If the sample also fails, clean the vat in the next step.

2. Clean the vat and filter the resin

   Wearing nitrile gloves, remove cured debris with a plastic scraper, filter the resin and inspect the film. Replace it if it is cloudy, scratched or damaged.

   Check: The film is clean and clear, and the resin has no bits in it.

   If that does not fix it: Check how the build plate is fastened.

3. Tighten the build plate

   With the printer stopped, tighten whatever holds the build plate and check that it does not move. If you had to readjust it, re-level before printing.

   Check: The build plate has no play when pushed.

   If that does not fix it: Check orientation and supports.

4. Change orientation and supports

   In the slicer, tilt the part so the area changes little from one layer to the next, add supports to hanging areas and avoid cavities that act as suction cups. Hollow out large solid parts.

   Check: The layer preview shows no sudden jumps in area and no unsupported areas.

   If that does not fix it: Avoid long pauses and check the file.

5. Avoid long pauses

   Fill enough resin before starting and, if the printer asks for more, top it up to the mark straight away; Prusa says within 3-5 minutes at most. After a long pause, layers may not bond well.

   Check: The print finishes with no pauses or warnings.

   If that does not fix it: Re-slice the model or download it again.

6. Check the file and the UV light

   Re-slice the model or download it again in case the file is corrupted. If the manufacturer's samples also fail with a clean vat, run the screen test (LCD screen and UV light sheet).

   Check: With the new file, the part prints without separation.

   If that does not fix it: Contact the manufacturer's support with photos of the part and the film.

Prevention

• Check and clean the vat after every failed print.
• Print large parts tilted and hollow out solid ones with drain holes.
• Make sure you have enough resin before long prints.

Still not fixed?

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Printers it applies to

Any resin (MSLA/SLA) 3D printer, from any brand.

Official sources

This guide summarises the official documentation linked here:

• Delamination · Formlabs
• De-lamination / separated layers (SL1/SL1S) · Prusa Research
• Warped layers (SL1/SL1S) · Prusa Research