Corners lift off the bed mid-print. You’ll hear the nozzle snagging on the curled edge, or you’ll come back to find the part knocked loose entirely.
Identify the Pattern
- Corners only, flat bottom: Classic thermal warp. The part cooled faster at the edges than the center. Fix: bed temperature, brim, slow fan.
- Whole bottom layer lifting uniformly: Z-offset too high. The first layer never actually stuck.
- One side lifting, one side fine: Bed not level, or airflow hitting from one direction.
- Happening mid-print (not just the bottom): Ambient temperature swings. Enclosure or draft exclusion needed.
Fixes
Bed temperature — the first dial to turn
ABS at 90°C bed will warp without fail. Minimum for ABS/ASA is 100°C, target 105–110°C. For PLA, 60–65°C is usually enough; 50°C beds are only reliable with PEI surfaces and small prints. Raise the bed temp 5°C and wait 3 minutes before reprinting — the surface needs to fully soak through.
Z-offset — often overlooked
A first layer that’s slightly too far from the bed looks fine visually but barely grips. Run your fingernail along the first layer lines: they should be slightly squished together, not round-topped. If they’re round, lower the Z-offset 0.05mm at a time.
Brim width
For ABS under 150mm footprint: 8mm brim minimum. For anything larger: 12–15mm. A brim adds contact area and slows down edge cooling. Don’t expect glue stick alone to compensate for a missing brim.
Enclosure
ABS and ASA need one. An enclosure doesn’t have to be sealed — even three cardboard walls around an open printer cut draft enough to prevent the 30–40°C ambient drop that causes delamination cracking. A proper enclosure holds 40–50°C chamber temperature passively.
Cooling fan for first layers
Turn it off for the first 3 layers on ABS/ASA. For PLA on large flat parts, drop it to 30% for layers 1–5. Full cooling on layer 1 is the single fastest way to cause corner lift on flat-bottomed parts.
Surface preparation
Glue stick (Pritt or equivalent) on glass works for PLA and PETG. For ABS, the bed surface matters more: PEI sheet at 105°C is the most reliable option. Kapton tape is a distant second. Garolite (FR4) is used for nylon. Clean PEI with IPA before every session — fingerprint oils are enough to kill adhesion.
What Doesn’t Work
Raft alone without fixing temperature won’t solve chronic warping — it just moves the warp to the raft-to-part interface. Mouse ears (small circles at corners) are faster than a full brim for parts with only 2–3 problem corners.