Quick answer
3D prints warp because the plastic shrinks as it cools, and uneven cooling pulls the corners up off the bed. The fix is to keep the part warm and evenly heated (correct bed temperature, no drafts, an enclosure for ABS) while anchoring it down hard with a clean first layer and a brim. Get those two things right and lifting corners almost always disappear.
Why prints warp and lift at the corners
Every thermoplastic contracts as it cools from melt temperature back to room temperature. The outer edges and corners of a print cool fastest, so they shrink first and curl upward while the warm centre stays put. That internal stress is what peels corners away from the build plate. Shrinkage-prone materials warp the most, roughly PC, then nylon (PA/PA-CF), ABS, ASA, PETG, and finally PLA, which warps the least. Large footprints, sharp corners, and thin first layers all make it worse.
1. Set the correct bed temperature
A bed that is too cold won’t hold the first layer; one that is too hot can leave corners soft enough to curl. Use roughly 55-60C for PLA, 70-85C for PETG, and 90-110C (commonly 100C) for ABS/ASA. On a Bambu Lab machine, selecting the right filament profile sets these automatically, so start there before hand-tweaking.
2. Add a brim (or mouse ears) for grip
A brim is the single most effective anti-warp tool. Add a 5 mm brim in your slicer to give the outer walls extra surface area gripping the plate. For tall parts with small footprints, use “mouse ears” (small printed discs at each corner) to hold the worst offenders down.
3. Eliminate drafts and keep the heat in
A cool breeze from an open window, an AC vent, or a nearby fan cools one side of the print faster than the other and causes warping. Close doors and windows for PLA and PETG. For ABS and ASA, an enclosure is essentially required; it traps heat and keeps the whole part near the same temperature so it shrinks evenly.
4. Clean the plate and improve first-layer adhesion
Grease and fingerprints kill adhesion. Wash the plate with warm water and dish soap (or wipe a textured PEI plate with isopropyl alcohol) and handle it by the edges. For stubborn materials, a thin layer of glue stick adds grip, and on PETG it also acts as a release agent so the part doesn’t bond too hard and chip the plate.
5. Tame cooling on the first few layers
Part-cooling fans that blast the first layers cause rapid, uneven contraction. Keep the fan off or very low for the first few layers, especially for PETG and ABS. PLA tolerates more cooling, but ramping the fan up gradually still helps the base stay anchored.
6. Re-level the bed and check your Z-offset (Bambu Lab)
If only one corner lifts, the nozzle is probably too far from the plate there. Re-run automatic bed leveling, confirm the correct plate type is selected in Bambu Studio, and adjust the Z-offset so the first layer is lightly squished, flat and slightly flattened, not round and barely touching.
7. Reduce stress on large or sharp-cornered parts
Big flat parts and sharp 90-degree corners concentrate the most stress. Where you can, add fillets to sharp corners in your model, lower infill density a little to reduce internal pull, and slow the first layer speed so it lays down cleanly and bonds fully.
Frequently asked questions
Why does only one corner of my print lift?
That corner is usually cooler or the nozzle is too high there. Check for a draft on that side and re-level the bed, paying attention to Z-offset.
Does a brim really stop warping?
Yes, a brim adds gripping surface around the part and is the fastest, most reliable fix for lifting corners, especially on PETG and ABS.
Do I need an enclosure to print ABS without warping?
For anything beyond small parts, effectively yes. ABS shrinks a lot and needs the still, warm air an enclosure provides to cool evenly.
Why does PLA warp when it’s supposed to be the easiest material?
Usually a cold or dirty bed, a draft, or too much fan on the first layers. Clean the plate, set the bed to about 55-60C, and shield the printer from breezes.