HOW TO CONFIGURE PART COOLING

Part cooling is the air the small fan on the print head blows directly at the freshly extruded plastic. It controls how fast layers solidify, which determines: overhang quality, bridge sag, layer adhesion strength, and how much heat soaks into the rest of the model. Different filaments need different cooling - PLA loves it, ABS hates it, PETG is in between. Most slicers expose at least three cooling-related settings: regular fan speed, overhang fan speed (boosts cooling on overhanging perimeters), and bridge fan speed (max cooling on bridges). Some slicers also expose top-surface fan speed separately. Set them per filament family, save in the profile, forget about it.

Configure cooling when: opening a new filament type for the first time, overhangs are sagging, bridges are dropping, layer adhesion is weak, or top surfaces are pillowing. Don't change defaults when: the slicer profile is already correct for the filament and prints look clean. Default Bambu / Prusa / OrcaSlicer profiles for common filaments are well-tuned.

Per-filament starting points (regular print fan): - PLA / PLA+: 100% from layer 3+. - PETG: 30-50% from layer 4+. - ABS / ASA: 0-30% maximum (open-air); 20-40% with enclosure for some cooling on overhangs. - PC / PC-blend: 0% (most), 20% on overhangs only. - TPU: 50-70% (TPU benefits from cooling but not as aggressive as PLA). - Nylon: 0% (cooling weakens layer bonds severely). First-layer fan handling: - PLA: off layers 1-2, then ramp to 100%. - PETG: off layers 1-3, then ramp to 30-50%. - ABS / ASA: off layers 1-5, then 0-30%. - All filaments: first-layer cooling off improves bed adhesion. Skip this and the first layer can lift before subsequent layers print over it. Overhang fan speed (separate setting): - PLA: 100% (already at 100% normally, but ensure overhang setting matches). - PETG: 70-80% on overhangs (boost from regular 30-50%). - ABS / ASA: 30-50% on overhangs (boost from regular 0-30%). - Trick: use a separate overhang fan boost so non-overhang prints still benefit from low fan, while overhangs get extra cooling. Bridge fan speed (separate setting): - PLA: 100%. - PETG: 70-80%. - ABS / ASA: 30-50% (max your filament tolerates without delamination). - Bridges always need maximum cooling. Set this regardless of regular fan speed. Slicer-specific: - Cura: Cooling section. Fan Speed (regular), Initial Fan Speed (first layer), Regular/Maximum Fan Speed Threshold (auto-ramp by speed). Bridge fan is in Experimental. - PrusaSlicer: Filament Settings - Cooling. Min/max fan speed, layer time-based fan speed. - OrcaSlicer / Bambu Studio: Cooling - regular, overhang, bridge fan separately exposed.

Copying PLA fan settings to PETG. PETG at 100% fan delaminates badly. Each filament needs its own profile. Fan on for the first layer. Reduces bed adhesion - first layer can lift. Always 0% for layers 1-2 (PLA) or 1-5 (ABS). No overhang fan boost. Default fan speed might be fine for normal walls but inadequate for overhangs. Use the dedicated overhang fan setting. Maximum fan on tall thin walls. Cools the wall so fast that adjacent layers can't bond properly. Reduce fan on tall narrow features specifically. Bridge fan set the same as regular fan. Bridges always need max cooling regardless of normal fan speed. Set separately. 100% fan on ABS / ASA without an enclosure. Open air + 100% fan + ABS = warping disaster. Drop fan to 0-30% on ABS / ASA always.

For weak overhangs that the right fan settings don't fully fix, see weak-overhangs. For poor bridging, see poor-bridging. For layer separation caused by excessive cooling, see layer-separation.