3D printing · Guide · By Mohammed Almuhanna · Updated June 2026

3D Print Warping: Why Corners Lift and How to Fix It

Warping is when the corners and edges of a print curl up and away from the bed as the plastic cools and contracts. The lifted edge pulls the part loose from the build surface, ruins the flatness of the bottom, and on a bad night peels the whole model off mid-print. Every plastic shrinks as it goes from molten to solid, and the more it shrinks, the harder it fights to lift its own corners. ABS and ASA are the worst, PLA the mildest. I print mostly ASA on an enclosed machine in a hot Gulf climate, so I fight this constantly, and one thing I have learned is that stock cooling advice does not always survive the local heat. Treat generic fan numbers as a starting point you tune, not gospel. Work the fixes below from the top, because keeping the part warm with a hot bed and an enclosure does most of the work.

Why warping happens

Plastic comes out of the nozzle hot and shrinks as it cools, and a print never cools evenly. The bottom layers, sitting against the bed and exposed to the air, cool and contract first while the layers above them are still hot and soft. Those lower layers want to pull inward as they shrink, and that contraction puts the corners under tension. When the pull at the edges beats the grip of the first layer on the bed, the corner lifts. Big flat parts give the contraction a long lever to work with, and sharp 90 degree corners concentrate the stress, so wide bases with square corners warp first and worst.

Bed temperature and a clean, level bed

A heated bed is your main defence, so run it hot. A hot bed keeps the first few layers warm and soft so they shrink less and stay put while the rest of the part builds on top. Run the right temperature for the material. PLA around 60C, PETG around 70 to 80C, and ABS and ASA around 100 to 110C. Too cool a bed for the material and the corners start lifting almost immediately.

None of that matters if the part is not gripping the plate in the first place. A clean, level bed with a properly squished first layer is the foundation everything else sits on. Wipe the surface free of grease, level it, and dial the first layer so it is pressed in rather than laid on loosely. If you are fighting adhesion as well as warping, sort the sticking first: see 3D print bed adhesion.

An enclosure for ABS and ASA

If you print ASA or ABS, get an enclosure. I run ASA on an enclosed machine and it is the single thing that keeps the corners down. An enclosure is a box around the printer that traps the heat the machine gives off and holds the air around the part warm. That warm chamber lets the whole print cool slowly and evenly, so the bottom layers are not racing ahead of the top and the contraction stress never builds up enough to lift a corner. For PLA you can usually skip it. For ABS and ASA it is close to mandatory. Without an enclosure the corners lift no matter how hot the bed is, because the upper part of the print is cooling in open room air while the base bakes against the plate. Even a simple draught-tight box around the machine makes the difference between a flat part and a banana.

Turn off part cooling for warpy materials

The part cooling fan blows air straight at the print to freeze each layer quickly. PLA loves that, because fast cooling gives crisp overhangs and clean detail. ABS and ASA hate it, because blasting cold air onto the part cools it fast and unevenly and drives the warping you are trying to stop. Keep the fan off, or very low, for ABS and ASA. Leave it on full for PLA. PETG sits in between and usually wants only light cooling.

Brim and raft

Both buy you more grip at the edges, and I reach for a brim before a raft every time. A brim is a flat skirt of plastic printed in the first layer, fused to the outside of the part and spreading out across the bed. It widens the footprint and anchors the corners down with extra surface area, and because it is only one layer thick it peels off cleanly and wastes very little filament. A raft is a printed base that the part sits on top of, giving the model a fresh flat surface instead of the bed and soaking up the warping stress in the raft rather than the part. Reach for a brim first since it is cheaper and faster, and move to a raft only when the part still lifts or the bed itself is uneven.

Draft shield and environment

A sudden cold draught across one side of a print cools that side faster than the rest and pulls a corner up. Keep the printer out of the path of air conditioning, fans, and open windows, and do not crack a door next to it mid-print. If you cannot fully enclose the machine, most slicers offer a draft shield, a thin single-wall fence printed around the part that blocks moving air and holds a pocket of still, warmer air against the print. It is no substitute for a real enclosure on ABS, but it helps on PETG and in a breezy room.

Material note

The simplest fix is picking a material that does not warp in the first place. By how much they shrink and lift, the order runs ABS the most, then ASA, then PETG, then PLA the least. If the part does not actually need the heat resistance or outdoor durability of ABS or ASA, and you cannot run an enclosure, print it in PLA or PETG and the warping problem mostly disappears on its own. Match the material to the job and your setup rather than fighting a warpy filament you did not need. For a full rundown of what each one is good for, see 3D printer filament types.

Anti-warping checklist

Set the bed to the right temperature (PLA ~60C, PETG ~70 to 80C, ABS and ASA ~100 to 110C) on a clean, level plate with a squished first layer.
Enclose the printer for ABS and ASA so the part cools slowly and evenly.
Turn the part cooling fan off or very low for ABS and ASA; leave it on full for PLA.
Add a brim for extra edge grip, and move up to a raft only if the part still lifts.
Keep drafts, AC, fans, and open windows off the printer, and use a slicer draft shield if you cannot enclose it.
If the part allows it, print in PLA or PETG instead of ABS or ASA to sidestep warping entirely.

What a warped print costs you

A part that warps off the bed is a scrapped print: the filament is wasted, the machine time is gone, and you are starting over. The 3D print cost calculator covers this with a failure buffer that adds a percentage on top of every job for the prints that do not come out right, so a warped first attempt in the bin does not eat into what you charge.

Common questions

Why do my 3D prints warp at the corners?

Plastic shrinks as it cools, and a print does not cool evenly, so the lower layers contract first while the layers above are still hot. That contraction puts the corners under tension, and when the pull beats the grip of the first layer on the bed, the corner lifts. Big flat parts and sharp 90 degree corners warp first and worst.

Which filaments warp the most?

By how much they shrink and lift, the order runs ABS the most, then ASA, then PETG, then PLA the least. If a part does not need the heat resistance or outdoor durability of ABS or ASA and you cannot run an enclosure, printing it in PLA or PETG mostly sidesteps warping on its own.

Does an enclosure stop warping?

For ABS and ASA it is close to mandatory. An enclosure traps the printer's heat and keeps the air around the part warm, so the whole print cools slowly and evenly and the contraction stress never builds up enough to lift a corner. PLA can usually skip it.

Should I turn off the part cooling fan to reduce warping?

For ABS and ASA, yes. Blasting cold air onto those materials cools them fast and unevenly and drives the warping, so keep the fan off or very low. Leave it on full for PLA, where fast cooling gives crisp detail, and use only light cooling for PETG.