How to Fix PETG Warping

PETG sits in the comfortable middle of the warping scale: far tamer than ABS, slightly more demanding than PLA. When PETG corners lift anyway, the cause is almost always a bed below its happy window, an over-eager part fan, or grease — and all three are quick to fix.

How much PETG actually shrinks

PETG’s shrinkage is modest, and it stays rubbery well below its printing temperature — it softens around 60 °C (its vitrification point). Keep the bottom of the part above that temperature and the shrink forces stay too weak to lift a clean, properly heated plate. That is the entire game with PETG: warm base, moderate cooling.

Quick fixes

1. Bed to 70–80 °C. Bambu’s stock PETG profile runs 70 °C on textured PEI; if corners lift, go up ~5 °C toward 80. Vendor baselines across the industry agree on this window — Creality, Voron, RatRig and most others default PETG beds to 80 °C. On a SuperTack plate stay at 60 °C maximum — and note PETG is marked incompatible with the Cool Plate (bed temperature 0 in the profile means unsupported).

Filament settings → Filament (bed temperature row for your plate)

2. Tame the fan. PETG wants gentle cooling: the stock window is 30–60 % with no fan for the first 3 layers. A PLA-style 100 % fan freezes each PETG layer into tension and will curl corners on an otherwise perfect setup. On machines with an auxiliary side fan, the PETG profile keeps it at 0 % — verify it really is off.

Filament settings → Cooling

3. Wash the plate with dish soap. PETG grips PEI ferociously when the surface is clean and lets go embarrassingly easily when it is greasy. Warm water, dish soap, a clean towel — not just an IPA wipe, which smears the oil around.

If corners still lift

Special case: tall, thin PETG parts

A tall vase or bracket in PETG can develop mid-height warp — the part bends away from the auxiliary fan side on enclosed CoreXY machines. That is uneven cooling, not bed adhesion: confirm the auxiliary fan is at 0 % for PETG and, if the geometry is extreme, drop the main fan toward the bottom of its window. The general mechanics of uneven-cooling warp are covered in the main warping guide; PETG’s complete value table lives in the PETG settings guide.

Frequently asked questions

Why do PETG corners lift off the bed?

Almost always one of three causes: a bed below PETG’s happy window, an over-eager part-cooling fan, or a greasy plate. PETG softens around 60 °C, and as long as the bottom of the part stays above that temperature the shrink forces are too weak to lift it off a clean, properly heated plate. Warm base plus moderate cooling is the entire game with PETG.

What settings stop PETG warping?

Bed at 70–80 °C — Bambu’s stock PETG profile runs 70 °C on textured PEI, and Creality, Voron, RatRig and most vendors default to 80 °C (SuperTack maximum 60 °C, Cool Plate unsupported). Fan in the 30–60 % window with no fan for the first 3 layers, auxiliary side fan at 0 %, first layer at 20 mm/s — and if corners still lift, an outer brim of 8 mm.

How do I tell PETG warping from an adhesion failure?

Look under the lifted corner. If it shows clean plate texture underneath, that corner never bonded — it’s a bed-adhesion failure, so wash the plate and work through PETG adhesion fixes instead. True warping pulls a previously bonded corner up as the part shrinks. Mid-height warp on tall, thin parts is uneven cooling: confirm the auxiliary fan is at 0 % for PETG.

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