How to Fix Layer Separation in 3D Prints
Cause 1: nozzle temp too low
Each new layer needs to partially re-melt the layer below to bond. If the nozzle is too cool, the new layer sits on top instead of fusing. Raise the nozzle 5 to 10 C and test.
Cause 2: layer fan too aggressive
Fast cooling can drop the layer surface below bonding temperature before the next layer arrives. For PETG, ABS and nylon, drop the layer fan to 30 to 50 percent. For PLA, 100 percent is usually fine unless the print has overhangs and bridges only.
Cause 3: wet filament
Water in the filament foams at the nozzle, leaving gaps in the layer that fail to bond. Symptoms: popping sounds during printing, dull surface, separation at random layer heights. Dry the spool and re-test.
Cause 4: line width and layer height mismatch
If the layer height is more than 75 percent of the nozzle diameter, the layers do not squish enough to bond. For a 0.4 mm nozzle, keep layer height at or below 0.3 mm. For a 0.6 mm nozzle, 0.45 mm max.
Cause 5: drafts and enclosure
Cold air across the print causes uneven cooling. ABS and nylon are most sensitive. An enclosure or even a cardboard box over the printer for the duration of the print is usually enough.
Cause 6: nozzle worn or partially blocked
A partial clog causes under-extrusion, which causes weak layers. Clean the nozzle with a cold pull or swap it out.
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PETG and ABS are the most layer-separation-prone materials and the most-rewarding to tune correctly.