3D print failure library
What each common failure looks like, what usually causes it (most likely first), and the fix to try first. Not sure which one you have? The Failure Finder reads your photos and your G-code and tells you.
Stringing / whiskers Corners lifting / warping Won't stick to the bed Stuck too hard to the bed Spaghetti / failed mid-print Layer shift Layers splitting or cracking Gaps / under-extrusion Blobs and zits Elephant foot Droopy overhangs Bridges sagging Clicking / clogged nozzle Filament snaps / brittle Parts the wrong size Supports won't come off Soft / see-through section Ripples after corners (ringing) Stringing / whiskers Fine hairs or cobwebs between separate parts of the print.
Usual causes, most likely first Wet filament: water boils in the nozzle and keeps pushing plastic out (PETG, nylon and TPU especially). Nozzle too hot for that filament. Retraction too short or too slow for your extruder. Travel moves crossing open air instead of staying inside the part. Fixes, in order Dry the spool, then print the same file again. If the strings shrink, moisture was the cause. Lower the nozzle 5 °C at a time, staying inside the spool's range. Run the retraction test in your slicer's Calibration menu. Turn on 'Avoid crossing walls' (OrcaSlicer, Bambu Studio) or 'Combing' (Cura). A quick check: if you hear popping or see steam at the nozzle, the filament is wet.
Diagnose my stringing problem →
Corners lifting / warping Corners peel up off the bed; the bottom of the part curves.
Usual causes, most likely first Plastic shrinks as it cools and pulls the corners up. ABS, ASA, nylon and PC shrink the most. Drafts or cold room air, or an open enclosure. Bed too cool, or a dirty plate (fingerprints are enough). Part cooling fan too high for that material. Fixes, in order Wash the plate with dish soap and hot water, then don't touch the print surface. Use a brim (5–8 mm) on parts with sharp corners. Keep the enclosure closed and let the bed heat the chamber for 10–15 minutes before printing ABS/ASA/PC. Lower part cooling for shrink-prone materials. Rounded corners in your design warp far less than sharp ones.
Diagnose my corners lifting problem →
Won't stick to the bed The first layer drags around, curls up, or never sticks at all.
Usual causes, most likely first Nozzle too far from the bed (first layer is round beads, not flattened lines). Oily or dusty plate. Bed too cool for the material. First layer printing too fast. Fixes, in order Clean the plate with dish soap and hot water. Isopropyl alcohol alone only moves oil around. Re-run bed leveling, then adjust Z-offset until the first layer lines are slightly flattened and touching. Use the bed temperature from the spool label. Slow the first layer to about 30–50 mm/s. Diagnose my won't stick to the bed problem →
Stuck too hard to the bed The part won't come off, or it pulls chunks out of the build plate.
Usual causes, most likely first PETG and some engineering plastics bond chemically to smooth PEI and glass. First layer squished too much (nozzle too close). Over-extrusion, very common with foaming filaments if flow isn't reduced. Fixes, in order Use glue stick on the plate as a release layer, or switch to textured PEI. Let the bed cool fully; most parts release on their own. Raise Z-offset slightly. For foaming filament, cut flow ratio to the maker's range. Diagnose my stuck too hard to the bed problem →
Spaghetti / failed mid-print A nest of loose strands where the part should be.
Usual causes, most likely first The part came loose from the bed and the printer kept going. A support or thin feature broke off and got dragged. A clog stopped extrusion partway, then partly recovered. Fixes, in order Treat it as an adhesion problem first: clean the plate, add a brim. Check whether tall thin parts need supports or a wider base. If extrusion stopped, see Clicking / clogged nozzle. Diagnose my spaghetti problem →
Layer shift The print suddenly steps sideways at one height, like a staircase.
Usual causes, most likely first The nozzle hit a curled-up edge or blob and the motor skipped. Loose belt or pulley set screw. Moving too fast for the machine (too high acceleration). Fixes, in order Look for curled edges or blobs at the shift height; fix the cooling or flow problem that made them. Check belt tension and tighten pulley screws (on most printers it's in the maintenance menu or manual). Lower acceleration and speed for that print. Diagnose my layer shift problem →
Layers splitting or cracking Cracks between layers, often on tall parts or at corners.
Usual causes, most likely first Layers cooled too fast before the next one bonded (ABS, ASA, PC, nylon). Nozzle too cold. Too much part cooling or a draft. Layer height too large for the nozzle. Fixes, in order Close the enclosure and reduce part cooling. Raise the nozzle 5–10 °C inside the spool's range. Keep layer height under 75% of the nozzle diameter. Diagnose my layers splitting or cracking problem →
Gaps / under-extrusion Thin or missing lines, gaps between walls, weak spongy parts.
Usual causes, most likely first Partial clog or worn nozzle. Printing faster than the hotend can melt (max volumetric speed). Filament tangled or binding on the spool. Flow ratio too low, or heat creep softening filament above the melt zone. Fixes, in order Do a cold pull or replace the nozzle. Lower speed, or set the max volumetric speed from the maker's profile. Make sure the spool turns freely. Run the flow ratio test in your slicer's Calibration menu. Diagnose my gaps problem →
Blobs and zits Small bumps on walls, usually where each layer starts.
Usual causes, most likely first Seam position: every layer starts and ends at one spot. Pressure advance not tuned. Over-extrusion or wet filament. Fixes, in order Set seam to 'Aligned' or 'Back' so the bumps line up out of sight; or try scarf seams in OrcaSlicer. Run the pressure advance test in the Calibration menu. Dry the filament and check the flow ratio. Diagnose my blobs and zits problem →
Elephant foot The bottom layers flare out wider than the rest of the part.
Usual causes, most likely first First layer squished too much. Bed too hot, so the bottom layers sag. Fixes, in order Raise Z-offset a little. Lower the bed temperature 5 °C. Use 'Elephant foot compensation' in your slicer (around 0.1–0.2 mm). Diagnose my elephant foot problem →
Droopy overhangs Undersides of slopes and arches curl down or look rough.
Usual causes, most likely first Not enough cooling on the overhang. Overhang steeper than the material can manage (beyond about 45–60°). Printing overhangs too fast. Fixes, in order Raise overhang fan speed (not for ABS/ASA). Add a 45° chamfer in the design instead of a flat overhang, or add supports. Use slower overhang speeds in the slicer. Diagnose my droopy overhangs problem →
Bridges sagging Lines spanning a gap droop or break.
Usual causes, most likely first Too little cooling while bridging. Bridge too long. Bridging too fast, or flow too high. Fixes, in order Use full fan for bridges (PLA/PETG). Shorten the gap in the design, or add a small support rib in the middle. Lower bridge flow and speed in the slicer. If the gap is enclosed on all sides, slicer supports can't reach it. Change the model instead.
Diagnose my bridges sagging problem →
Clicking / clogged nozzle The extruder clicks or grinds; little or nothing comes out.
Usual causes, most likely first Heat creep: filament softens too high in the hotend (often from a failing heatsink fan or a hot enclosure with PLA). Debris or burnt plastic in the nozzle. Nozzle too close to the bed on the first layer. Filament with swollen or wet sections. Fixes, in order Check the hotend heatsink fan is spinning and quiet. Do a cold pull, or swap the nozzle. Raise Z-offset slightly. Pull the filament out and look at the tip; a swollen, mushroom-shaped end points to heat creep. Diagnose my clicking problem →
Filament snaps / brittle Filament breaks in the tube or on the spool before it reaches the hotend.
Usual causes, most likely first PLA becomes brittle with age and moisture. Some fiber-filled filaments break if dried too hot or too long. Tight bends in the feed path. Fixes, in order Dry it at the spool's recommended temperature, not hotter. Store in a dry box. Straighten the feed path so the filament doesn't bend sharply. Diagnose my filament snaps problem →
Parts the wrong size Holes too small, pegs too big, or parts measure off the design.
Usual causes, most likely first Plastic squishes outward on every wall (normal). Holes print small because the inside curve is undersized. Shrinkage on larger parts (ABS, ASA, nylon). Fixes, in order Measure a test print with calipers and use Fit Check to get the exact compensation numbers. Use 'X-Y hole compensation' and 'X-Y contour compensation' in OrcaSlicer/Bambu Studio ('Horizontal expansion' in Cura). For large parts, scale by the measured shrinkage percent. Diagnose my parts the wrong size problem →
Supports won't come off Supports fuse to the part and leave scars.
Usual causes, most likely first Support top gap too small for that material. Too many support interface layers (PETG especially sticks to itself). Fixes, in order Raise the support top Z distance (0.2 → 0.3 mm on a 0.4–0.6 mm nozzle). Use a different material for the interface if your printer has more than one. Rotate the part so fewer surfaces need support. Diagnose my supports won't come off problem →
Soft / see-through section Part prints fine, then above a certain height turns weak, thin or translucent.
Usual causes, most likely first Under-extrusion starting at a height: heat creep as the enclosure warms up, a fan failing, or a partial clog. A height-based change in the file (slowdown, temperature or flow change). Filament tangle or spool binding partway through. Fixes, in order Check the file for changes at that height (the G-code checker does this). Open the enclosure lid a little for PLA/PETG; check the heatsink fan. Look at the spool for a tangle near where it failed. Diagnose my soft problem →
Ripples after corners (ringing) Faint waves repeating on the wall right after a sharp corner.
Usual causes, most likely first The printer shakes when it changes direction fast. Input shaping not calibrated. Loose frame, belts or a wobbly table. Fixes, in order Run the input shaping or resonance calibration your printer offers. Lower acceleration for the outer wall. Put the printer on a solid, heavy surface. Diagnose my ripples after corners (ringing) problem →