Warping and lifting corners

Plastic shrinks as it cools. When the top of a part cools and contracts faster than the layer glued to the bed, something has to give — and it is usually the corners. This is a temperature-gradient problem, so the fixes are all about cooling the part more evenly.

Looks like: Corners curl up off the bed and the bottom of the print is no longer flat.

Fixes, in the order worth trying

1 · Try this first

Stop the draft

An open window, an air conditioner, or a fan pointed at the printer will warp ABS and ASA every time regardless of settings. Even PETG suffers. This is the cheapest fix on the list and the most overlooked.

Enclose the printer, even crudely — a cardboard box or a photo tent works. For ABS and ASA an enclosure is not optional; for PLA it usually is not needed at all, and can cause heat creep instead.

2 · Try this first

Raise the bed temperature

Keeping the bottom of the part hot keeps it soft enough to relieve stress instead of tearing off the plate. Go to the top of the material range.

Build Plate Temperature: Cura → Material → ABS/ASA 100–110 °C · PETG 80–85 °C · PLA 60–65 °C
Bed temperature: OrcaSlicer → Filament → Filament → ABS/ASA 100–110 °C · PETG 80–85 °C

3 · Common cause

Reduce part cooling

Counter-intuitive but correct for high-shrinkage materials: the fan is what creates the temperature gradient tearing the part off the bed. ABS and ASA generally want almost no fan; PLA wants a lot.

Fan Speed: Cura → Cooling → ABS/ASA 0–20 % · PETG 30–50 % · PLA 100 %
Fan speed: OrcaSlicer → Filament → Cooling → ABS/ASA 0–20 % · PETG 30–50 %

4 · Common cause

Add a brim and round the corners

A brim holds the corners down mechanically while the part is most vulnerable. If you control the model, a 2–3 mm fillet on the bottom corners removes the stress concentration entirely — sharp corners warp first for the same reason cracks start at sharp edges.

Build Plate Adhesion Type: Cura → Build Plate Adhesion → Brim, 8–10 mm for ABS
Brim width: OrcaSlicer → Process → Support → 8–10 mm

5 · Less common

Switch material if the geometry is the problem

A long flat part in ABS will fight you forever. PLA shrinks about a fifth as much as ABS and PETG sits in between. If the part does not need heat resistance or toughness, the material is the variable worth changing.

Change one thing at a time. If you adjust temperature, retraction and speed together and the problem goes away, you have learned nothing and you will be back here next month. Re-print the same test object after each single change.

Frequently asked questions

Why does ABS warp so much more than PLA?

Shrinkage on cooling. ABS contracts roughly 0.7–0.8 % as it cools, PLA about 0.2–0.3 %. Over a 200 mm part that is well over a millimetre of pull for ABS — more than enough to peel a corner. It is a material property, not a printer fault.

Will a raft stop warping?

Sometimes, but it treats the symptom. A raft gives more surface area and a sacrificial layer to warp instead of your part, at the cost of material, time and a rough bottom surface. Fix the thermal environment first; reach for a raft when geometry leaves no other option.

My print warped only on one side. What does that mean?

Almost always a draft from one direction, or an uneven bed where one region runs cooler. Check whether the lifted side faces a door, window or vent, and compare bed temperature at the centre versus that corner with an infrared thermometer if you have one.