3D print warping: how to stop corners lifting off the bed
Warping happens when plastic shrinks as it cools and pulls the corners of a print up off the bed. Fix it with a clean plate and a well-squished first layer, the right bed temperature, a brim, and no drafts. For ABS, ASA, nylon and polycarbonate, add an enclosure and turn the part-cooling fan down.
- Clean the plate with isopropyl alcohol or dish soap and re-check the first layer.
- Set the bed for the filament: PLA 55–65 °C, PETG 70–85 °C, ABS 95–110 °C.
- Add a brim: 5 mm for PLA and PETG, 8–10 mm for ABS, ASA and nylon.
- Block drafts from windows, fans and air vents.
- ABS, ASA, nylon, PC: enclose the printer and keep part cooling at 0–25%.
Why do 3D prints warp?
Every thermoplastic shrinks as it cools from the nozzle down to room temperature. The first layer is held flat by the hot bed, but each new layer shrinks on top of it, and those stresses add up. When the pull is stronger than the bed's grip, the corners and edges lift. Corners go first because stress concentrates there.
Warping looks different depending on where the stress wins:
- Corners lifting off the bed: classic warping. Bed adhesion lost the fight.
- Cracks between layers higher up (layer splitting): the part stayed stuck, so the shrinkage tore layers apart instead. Common with ABS on open printers.
- Overhang edges curling up: local overheating, not shrinkage against the bed. More cooling helps there, which is the opposite of the ABS advice. See cooling, speeds and acceleration.
Which filaments warp the most?
The more a plastic shrinks and the higher its glass transition temperature (where it goes from rubbery to rigid), the more stress builds up as it cools to room temperature.
| Filament | Typical shrinkage | Bed temperature | Warping risk | Enclosure? |
|---|---|---|---|---|
| PLA | ~0.3% | 55–65 °C | Low | No; keep it open |
| PETG | ~0.5% | 70–85 °C | Low | No; keep the chamber cool |
| TPU 95A | ~0.5% | 40–60 °C | Very low | No |
| ASA | ~0.6% | 100–110 °C | High | Yes |
| ABS | ~0.7% | 95–110 °C | High | Yes |
| Polycarbonate (PC) | ~0.6% | 110–120 °C | High | Yes, ideally heated |
| Nylon | ~1.5% | 70–90 °C | Medium to high (dry it first) | Yes |
Shrinkage figures are typical for unfilled grades. Carbon- or glass-fibre filled versions shrink and warp noticeably less. For materials in depth, see ABS and ASA and the engineering materials guide.
Free PrintPal toolMaterial Shrinkage CalculatorGet the scale factor that compensates for ABS, ASA, nylon or PC shrinkage on dimension-critical partsOpen tool1. Start with a perfect first layer
Warping is a tug-of-war, and the first layer is your side of the rope. Prusa's first step for warping is the same as for adhesion: clean the plate with isopropyl alcohol and lower the Z-offset slightly so the first layer is pressed firmly in.
- Plate washed or wiped, no fingerprints
- First-layer lines flat and touching, no gaps
- First layer printed slowly (20–30 mm/s)
- Bed mesh or leveling run recently
If the first layer itself won't stick, work through first layer not sticking before going further.
2. Use the right bed temperature
A hot bed keeps the bottom layers warm and slightly soft, which relieves stress. Use the ranges in the table above, start in the middle and go up 5 °C if corners lift. On large beds, let the bed soak at temperature for several minutes first so the edges are as warm as the centre. Placing the part near the middle of the bed helps for the same reason.
Hotter isn't always better: a PLA bed much above 65 °C softens the base and can cause elephant's foot.
3. Add a brim, mouse ears or a draft shield
| Option | What it is | Best for |
|---|---|---|
| Brim ears (mouse ears) | Small discs attached only at the corners | Corner lifting on boxy parts. OrcaSlicer has a "Mouse ear" brim type; Bambu Studio lets you paint brim ears onto chosen corners. |
| Narrow brim (3–5 mm) | A flat ring of lines around the base | Small, tall or thin PLA and PETG parts |
| Wide brim (8–10 mm) | The same, wider | ABS, ASA, nylon and large flat parts |
| Draft shield | A thin wall printed around the whole part, full height | ABS or ASA on an open printer; it traps a pocket of warm air. Found in the skirt settings in PrusaSlicer and OrcaSlicer, and under Experimental in Cura. |
| Raft | A thick lattice under the part | Last resort for bad bed surfaces; leaves a rough bottom |
Keep the brim-to-object gap around 0.1 mm so the brim snaps off cleanly.
4. Enclose the printer for ABS, ASA, nylon and PC
An enclosure keeps the air around the part warm, so the upper layers don't cool and shrink as sharply. It's the single biggest fix for engineering plastics, and it also cuts drafts.
- Passive enclosure: most enclosed printers (and printer tents) are warmed only by the heated bed. That's enough for ABS and ASA once the chamber has warmed up.
- Active chamber heating: some printers heat the chamber themselves, for example the Bambu Lab H2D (up to 65 °C) and Prusa CORE One+ (up to 55 °C). That helps most with large ABS, ASA, PC and nylon parts.
Don't heat the chamber for PLA, PETG or TPU. Bambu Lab warns that high chamber temperatures with these materials can cause clogs, and Prusa recommends against enclosing PLA and PETG. On enclosed printers, open the door or lid for PLA.
Before printing ABS or ASA in an enclosure:
- Door and lid closed, part fan set low
- Bed heated for 10–15 minutes first to warm the chamber (some printers have a heat-soak or chamber preheat option)
- Filtration or ventilation sorted, since ABS and ASA give off styrene and fine particles. See the 3D printing safety guide.
- Don't open the door until the print has cooled
5. Stop drafts and keep the room stable
A gentle breeze across an open printer cools one side of the part faster than the other, which is exactly how you get one lifted corner. Keep the printer away from windows, doors, fans and air-conditioning vents, and avoid cold garages. Prusa recommends a stable ambient temperature; a cardboard box or printer tent works as a basic draft blocker for PLA and PETG.
6. Turn down part cooling for warp-prone plastics
- ABS and ASA: part fan 0–25%. A little cooling (Prusa suggests around 10–20%) still helps overhangs and bridges.
- PETG: 30–50%.
- PLA: 100%, but it's fine to leave the fan off for the first layer or two.
- First layers: for warp-prone parts, Bambu Lab suggests no part cooling for the first 3 layers and turning the auxiliary side fan down.
7. Use the right surface and adhesion aid
Textured PEI grips ABS and ASA well, and Prusa recommends a glue stick layer on textured sheets for ABS, ASA, nylon and PC as a separation layer. Nylon is often printed on a Garolite (G10) plate with glue stick. Specialist adhesives sold for nylon or PC can help on large parts; follow the product's instructions and check that it's compatible with your plate.
8. Change the design or orientation
If a part still warps after all of the above, change the part.
- Round sharp corners in plan view. A 3–5 mm radius on vertical edges spreads the stress that a sharp 90° corner concentrates.
- Avoid large solid footprints. Split big flat parts, add relief cuts, or reduce solid bottom layers.
- Orient for a smaller contact patch when strength allows, and place parts toward the bed centre.
- Slow down. Prusa lists lower print speed as one of its warping fixes.
Design a 120 x 80 x 30 mm electronics enclosure for ABS printing: 2 mm walls, 5 mm radius on all vertical corners, a 0.5 mm chamfer on the bottom edge, and four M3 screw bosses inside.
A large ABS part on an open-frame printer starts lifting at the corners about 2 cm up. What's the best next step?
ABS needs warm, still air around it so upper layers don't shrink sharply. More cooling makes warping worse, and a hotter nozzle doesn't stop the part shrinking as it cools.
Frequently asked questions
Why do my 3D prints warp?
Plastic shrinks as it cools. Each new layer cools and pulls on the layers below, and when that pull is stronger than the grip on the bed, the corners lift. It is worst with ABS, ASA, nylon and polycarbonate, with large flat parts, and in cold or drafty rooms.
Does PLA need an enclosure to stop warping?
No. PLA shrinks very little, and a hot enclosed chamber can soften it and cause heat-creep clogs. Print PLA with the door or lid open, or with good ventilation, in a draft-free room. Enclosures are for ABS, ASA, nylon and PC.
How wide should a brim be to stop warping?
About 3–5 mm is enough for small or tall PLA and PETG parts. Use 8–10 mm for ABS, ASA and nylon. If only the corners lift, brim ears (mouse ears) at the corners use less plastic and are easier to remove.
What bed temperature stops ABS warping?
Use 95–110 °C for ABS and 100–110 °C for ASA. Bed heat alone rarely saves large ABS parts on an open printer, though; you also need an enclosure, low or no part cooling and a brim.
Related articles
Sources & further reading
- Prusa Knowledge Base — Warping
- Prusa Knowledge Base — Textured steel sheet
- Bambu Lab Wiki — Preventing warping
- Bambu Lab Wiki — Chamber temperature
- OrcaSlicer Wiki — Brim settings
- NIOSH — Approaches to safe 3D printing
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