Levelling the build plate of a resin printer

Symptom

The bottom layers do not stick on one side or in one corner, come out squashed and very thin or are missing, and the part stays on the film. It often happens with a new printer or when the build plate has moved or come loose.

Likely causes, from most to least likely

1. The build plate is not parallel to the screen: one side is further away than the other.
2. The zero position is wrong: if it is too high the bottom layers do not stick; if it is too low they come out squashed.
3. The build plate screws or knob are loose and it moves while printing.
4. There was resin or debris on the build plate or the screen when levelling.

Checks to tell which one it is

• Look at the base of a failed print: if it is thinner or missing on one side, the build plate is not parallel.
• With the printer stopped, push the build plate: it must not move.
• After levelling, pull the paper at the four corners: the resistance should be firm and similar at all of them.

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. Tighten anything loose

   Slowly but firmly tighten the screws or knob holding the build plate, and the vat screws evenly. If anything was loose, level again afterwards.

   Check: The build plate has no play when pushed.

   If that does not fix it: Level following the next steps.

2. Prepare the printer

   Wearing nitrile gloves, remove the vat and leave the build plate and the screen clean and free of resin.

   Check: The screen and the build plate are clean and dry.

   If that does not fix it: If there is hardened resin on the screen, clean it following the resin leak sheet.

3. Loosen the build plate

   Loosen the screws holding the build plate until it can move freely (on many printers there are four).

   Check: The plate tilts by hand.

   If that does not fix it: If your printer has no levelling screws, use the calibration or alignment wizard in its menu.

4. Lower the plate onto a sheet of paper

   Lay a sheet of paper on the screen (Phrozen gives an A4 sheet of 0.07-0.10 mm; some models or films need more sheets, check your manual) and start the levelling or Z calibration from the menu so the plate comes down onto the paper.

   Check: The build plate rests flat on the paper.

   If that does not fix it: If it does not come all the way down or stops early, check that nothing is underneath and repeat.

5. Tighten diagonally

   Press the build plate onto the paper with one hand and tighten the screws a little at a time in a diagonal, criss-cross order. Some manufacturers tighten in two passes.

   Check: Pulling the paper at each corner, you feel a firm and similar resistance.

   If that does not fix it: Loosen and repeat. If one corner is always loose, the plate may not be flat: contact the manufacturer.

6. Save the position and remove the paper

   Confirm the position in the menu (Z=0, Done or similar), wait for the build plate to rise and remove the paper.

   Check: The first test print has a complete, well-stuck base.

   If that does not fix it: Adjust the Z offset.

7. Fine-tune the Z offset if needed

   If the bottom layers come out squashed, raise the Z offset slightly if your printer allows it; Phrozen suggests 0.1 mm steps and testing with small parts. If they do not stick, check the exposure and the temperature.

   Check: The bottom layers have the expected thickness and stick well.

   If that does not fix it: Contact the manufacturer's support.

Prevention

• Level again if the build plate has moved or come loose.
• Clean the build plate and the screen before levelling.

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:

• [Sonic Mini 8K] Z-axis Calibration · Phrozen
• Why Are The Bottom Layers Missing Or Compressed? · Phrozen
• Adjusting build platform parallelism (Form 4 generation) · Formlabs
• Skewed / deformed prints (SL1/SL1S) · Prusa Research