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Why print corners lift off the bed, and what keeps warping parts flat

Published October 15, 202613 sources

Short answer

Warping is thermal shrinkage: the outer edges of a part cool faster than the center and the stress pulls the corners up, most often with PC, PA, ABS and ASA [1]. Start with a clean plate, the correct plate type in the slicer and the filament's bed temperature [2]. Then block drafts, keep part cooling off for the first 3 layers, add a brim or brim ears, and use an enclosure for high-temperature materials [4, 3].

How shrinkage turns into lifted corners

Prusa describes warping as the result of a sudden temperature difference between the hot nozzle and the surrounding air: the plastic shrinks as it cools, and the corners of large parts pull away from the bed. The aim is to reduce that thermal shock, which also leaves less residual tension in the part [4]. Bambu Lab adds the geometry: the outer edges cool faster than the center, so the tension concentrates at corners. Large parts, high infill and shrinkage-prone materials make it worse [1].

Bambu Lab ranks shrinkage risk from highest to lowest as PC, PA-CF, PA, ABS, ASA, PETG, PLA [1]. Prusa calls PETG low-warping because it expands very little with heat [13], yet Bambu Lab still documents PETG warping on P2S and X2D printers when cold chamber air blows directly on the part [3]. Slight warping can also be misread: Bambu Lab notes that small lifts leave defects on walls and top layers that look like a flow problem [1].

Symptom, likely cause, what to check

Symptom Likely cause What to check
Corners curl up mid-print; a ripple line on the side where the nozzle hit the lifted layer Thermal shrinkage Material choice, enclosure, bed temperature [1]
The whole part slides or pops off Adhesion failure: skin oil on the plate, wrong plate type in the slicer, Z offset too high Wash the plate, plate type, first layer [1]
One side lifts more than the others Draft from a window, AC vent or fan Block airflow around the printer [1, 4]
Even PLA and PETG lift in a cool room Ambient below 20 °C Raise the bed about 10 °C and remove drafts [2]
A supported area curls away from its supports Support-interface warping from cooling stress Supports or brim ears at those corners; less cooling [3]
The whole object lifts or cracks after the fan was turned up Too much part cooling Lower fan speed; raise nozzle temperature if layers crack [4]
Large, dense parts warp High infill with straight-line patterns Gyroid at 25% or less [1]

Diagnostic order

  1. Clean the plate. Bambu Lab washes plates with warm water and dish soap and says not to touch the surface afterward [1]; Prusa wipes with 90%+ isopropyl alcohol [4]. The bed adhesion guide covers which method suits which plate.
  2. Match the plate type in the slicer. Bed temperature differs by plate, so a wrong selection can leave the bed too cool. Bambu printers also lower the nozzle by 0.04 mm on the Textured PEI Plate; selecting a different plate removes that offset and leaves the first layer too high [2].
  3. Check the first layer. Prusa suggests lowering Live Adjust Z slightly for better grip, without over-squishing, and warns that PETG or PC can then bond hard enough to damage PEI [4]. See first layer and Z offset.
  4. Raise the bed temperature. Bambu Lab’s quick fixes are +5–10 °C, with a target of 55–65 °C for PLA on Textured PEI plus an 8–10 mm brim; for ABS and ASA it suggests +10–15 °C with all doors closed so the chamber reaches 40 °C or more [1].
  5. Reduce early cooling. Set No cooling for the first layers to 3 for PLA, PETG and TPU, and run the auxiliary fan at about 40–50% [2]. OrcaSlicer’s close_fan_the_first_x_layers does the same and is documented as reducing early-layer warping [9].
  6. Control the environment. Keep drafts away; Prusa recommends an enclosure if you mostly print high-temperature materials [4].
  7. Add hold-down geometry, covered next.

Brims, mouse ears and draft shields

  • Brim. Bambu Studio’s Auto brim widens the brim for PC, ABS, PA-CF, PET-CF and PLA-CF, for tall parts with small footprints, and at higher speeds; TPU gets a narrower one [5].
  • Brim ears. Set Bambu Studio’s brim type to Painted and paint ears only on the corners that lift [3]. OrcaSlicer offers a Mouse ears brim type: small local brims near corners that use less material than a full brim [7].
  • Discs or tabs. Bambu Lab shows adding disc parts at corners, giving them a different wall count so they separate cleanly, and setting elephant foot compensation to 0 so the joint stays flush [6]. Prusa suggests a small cylinder a few layers tall at the problem spot [4].
  • Draft shield. For PC Blend, ASA and ABS, Prusa recommends a skirt printed as a draft shield, printing several objects at once to hold heat, and placing problem areas toward the bed center [4]. OrcaSlicer’s draft_shield option is aimed at open-frame printers [8].

Cooling: too much or too little

PLA and PETG need strong part cooling, so Prusa first checks that the print fan works and is not blocked. For ABS or PC Blend in an enclosure, 10–20% fan can help steep overhangs and small features. Too much fan can lift the whole object and weaken layer bonding; if layers crack after raising the fan, raise the nozzle temperature [4]. Layers that split rather than lift are covered in layer separation.

Material and enclosure

Bambu Lab’s filament guide says ABS, ASA, PC, PA and their CF/GF grades need an enclosed printer for the higher bed and chamber temperatures that suppress warping, while PLA, PETG and TPU have no such requirement [11]. Large flat parts in ABS, ASA or PC will almost always warp without an enclosure; Bambu Lab suggests PLA, PLA-CF, PETG or PETG-CF instead [1]. The trade-offs between the two styrenics are in ABS vs ASA.

OrcaSlicer documents chamber temperature as a warping control for ABS, ASA, PC and PA, and says it should be disabled for PLA, PETG and TPU because softened filament at the heat break clogs the extruder [10]. For dense parts, Bambu Lab advises staying below 50% infill and using Gyroid, which shrinks more evenly than Grid or Triangles [2, 1].

Questions

Should I close the enclosure to stop PLA from warping?

Usually not. Bambu Lab recommends printing PLA with the door open or top cover removed when using a hot bed plate, because chamber heat can soften PLA and clog the extruder; it only suggests closing up in very cold rooms of about 5–10 °C [12]. Prusa also warns that PLA and PETG need strong cooling, which an enclosure makes harder [4].

Does a hotter bed always reduce warping?

Raising the bed 5–10 °C is one of Bambu Lab's first fixes for lifting corners [1], but OrcaSlicer notes that an overly hot bed softens the lower layers and causes elephant's foot [10].

Can wet filament cause warping?

Bambu Lab says moisture-absorbing filaments such as PETG extrude less stably when damp and become more prone to poor adhesion and warping, so it recommends drying them before printing [3].

Sources

  1. Model Warping, Falling Off, or Collapsing. Bambu Lab Wiki. Manufacturer documentation. Shrinkage mechanism, material risk order, bed temperature and brim targets, drafts, infill. Accessed October 12, 2026.
  2. Printed Model Warping: Causes and Solutions. Bambu Lab Wiki. Manufacturer documentation. Plate type and 0.04 mm offset, first-layer cooling, cold rooms, infill density. Accessed October 12, 2026.
  3. P2S/X2D Model Warping Troubleshooting. Bambu Lab Wiki. Manufacturer documentation. First-layer and support-interface warping, chamber airflow, cooling settings, moisture. Accessed October 12, 2026.
  4. Warping. Prusa Knowledge Base. Manufacturer documentation. Thermal shock, fan speed, ambient temperature, draft shield, brim, helper geometry. Accessed October 12, 2026.
  5. Brim. Bambu Lab Wiki. Slicer documentation. Auto brim width by material, shape and speed; painted brim ears. Accessed October 12, 2026.
  6. Tips for using discs to prevent warping. Bambu Lab Wiki. Slicer documentation. Adding disc parts at corners in Bambu Studio. Accessed October 12, 2026.
  7. Brim. OrcaSlicer Wiki. Slicer documentation. Brim types including mouse ears. Accessed October 12, 2026.
  8. Skirt. OrcaSlicer Wiki. Slicer documentation. Draft shield option for open-frame printers. Accessed October 12, 2026.
  9. Material Cooling. OrcaSlicer Wiki. Slicer documentation. No cooling for the first layers improves adhesion and reduces early warping. Accessed October 12, 2026.
  10. Material temperatures (bed, chamber). OrcaSlicer Wiki. Slicer documentation. Bed too low or too high; chamber temperature for ABS, ASA, PC, PA. Accessed October 12, 2026.
  11. Filament guide: printer, nozzle, AMS, build plate, glue compatibility and required parameters. Bambu Lab Wiki. Manufacturer documentation. Which filaments need an enclosed printer. Accessed October 12, 2026.
  12. Heat creep. Bambu Lab Wiki. Manufacturer documentation. Door and top cover guidance for PLA; closing up in very cold rooms. Accessed October 12, 2026.
  13. PETG. Prusa Knowledge Base. Manufacturer documentation. PETG described as low-warping due to little thermal expansion. Accessed October 12, 2026.