3D printing troubleshooting
What's wrong with your print?
From symptom to solution: identify the defect in two taps and fix it with a clear page — causes ranked by likelihood, each one's fix, and which material is to blame (when one is).
Where this comes from: every page is cross-checked against manufacturer documentation (Prusa Research, Bambu Lab) and reference technical guides (Simplify3D), cited with links at the end of each page. No advice without a source.
Quick diagnosis
Where is the problem?
All problems
Warping (lifted corners)
The part's corners lift off the bed mid-print, the base curls upwards and, in bad cases, the whole part breaks free halfway through.
Elephant foot
The first layers bulge outwards: the base ends up wider than the rest, with a squashed lip. It ruins fitting parts (boxes, lids) because the base no longer slots in.
Under-extrusion (gappy layers)
Lines come out thinner than normal, there are gaps between perimeters or in the infill, and some patches simply have no plastic. The part is weak and splits along layers.
Over-extrusion (blobs and fat edges)
Rough surfaces with excess plastic, bulging corners, fat seams and outer dimensions that measure oversized. The infill may 'clack' as the nozzle drags through surplus material.
Layer shift
From a certain height, every layer is offset to one side: the part is stepped along X or Y. It can happen once (one jump) or repeat at several heights.
Ghosting / ringing (echoes on walls)
After every corner or detail, the wall shows 'echoes': parallel ripples repeating the edge's silhouette, fading out. Most visible against the light on large flat walls.
Layer cracking (delamination)
Tall parts develop horizontal cracks between layers, sometimes with an audible 'crack' mid-print. The part splits cleanly along those lines under stress.
Clogged nozzle (not extruding)
No plastic comes out (or only a thin curly wisp), the extruder click-clicks skipping teeth or grinds the filament until it's chewed. Sometimes the print starts fine and dies a few layers in.
Pillowing (gappy top surface)
The part's top surface won't close properly: gaps between lines, small craters or bumps where the infill below shows through. The rest of the part looks fine.
Z-banding / z-wobble (horizontal bands)
Walls show regular horizontal bands — rings repeating every few millimetres at a constant rhythm, sometimes alternating fatter and thinner layers.
Blobs and zits (pimples on the surface)
Isolated pimples across the walls, often lined up vertically as a 'seam' — spots where the nozzle started or ended each layer and left extra plastic.
Sagging bridges (poor bridging)
Areas the printer lays 'in mid-air' between two anchors — bridges, hole ceilings, tops of openings — droop, dangle loose strands or fall outright.
Print won't stick to the bed
Full article on the blog →
Stringing (hairs between parts)
Full article on the blog →
And once your prints come out right…
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