Where did it go wrong, and what do I check first?
Pick what you are seeing. Each symptom has three checks in order — stop as soon as you find the cause. And change one thing at a time.
The general order: mechanical → material → heat and flow → speed → slicer settings. Most faults blamed on the slicer are wet filament or an unlevel bed. Change one thing, reprint one small test, write down what happened.
First layer won't stick
not sticking, first layer peels, dragged by the nozzle
- Check firstZ offset and bed levelMechanical
- ThenClean the bed with IPAMechanical
- LastRaise the bed 5–10 °CHeat and flow
Part lifts mid-print
warping, corners lift
- Check firstChamber heat, draughtsHeat and flow
- ThenAdd an 8 mm brimSlicer settings
- LastSwitch to a lower-shrink materialMaterial
Layers split apart by hand
layer cracking, weak layer bonding
- Check firstNozzle too coolHeat and flow
- ThenWet filamentMaterial
- LastTurn the part fan downSlicer settings
This can be wet filament — the most misdiagnosed fault there is. Quick test: extrude 100 mm with the fan off; wet strand bubbles or curls and snaps. Drying planner →
Stringing, fine hairs
cobwebs, hairs between parts, oozing
- Check firstMoisture — dry it firstMaterial
- ThenDrop the nozzle 5–10 °CHeat and flow
- LastIncrease retractionSlicer settings
This can be wet filament — the most misdiagnosed fault there is. Quick test: extrude 100 mm with the fan off; wet strand bubbles or curls and snaps. Drying planner →
Rough surface, popping sounds
crackling, hissing, bubbles, fuzzy surface
- Check firstWet filament, almost certainlyMaterial
- ThenUneven filament diameterMaterial
- LastClean the heater blockMechanical
This can be wet filament — the most misdiagnosed fault there is. Quick test: extrude 100 mm with the fan off; wet strand bubbles or curls and snaps. Drying planner →
Under-extrusion, thin walls
gaps in walls, missing lines
- Check firstNozzle worn wide or partly blockedMechanical
- ThenExtruder idler tensionMechanical
- LastCalibrate flow and e-stepsHeat and flow
Nozzle clogs mid-print
jam, heat creep, stops extruding
- Check firstHeat creepHeat and flow
- ThenOversized or dusty filamentMaterial
- LastHot end heatsink and fanMechanical
Layer shift on one axis
shifted layers, staircase
- Check firstLoose pulley on the motor shaftMechanical
- ThenAcceleration too highSpeed and motion
- LastStepper driver currentMechanical
Curled corners, soft edges
corners curl up, blobby edges
- Check firstNot enough coolingSlicer settings
- ThenTemperature too highHeat and flow
- LastSlow the outer wallsSpeed and motion
Holes in the top surface
pillowing, gaps on top
- Check firstToo few top layersSlicer settings
- ThenUnder-extrusionHeat and flow
- LastRaise infill overlapSlicer settings
Small features off-size
holes too small, parts don't fit, tolerance
- Check firstMaterial shrinkage compensationMaterial
- ThenFlow calibrationHeat and flow
- LastDrop the temperature 5 °CHeat and flow
Overhangs droop
sagging overhangs, ugly underside
- Check firstPart cooling fanSlicer settings
- ThenOverhang speedSpeed and motion
- LastAdd support or reorient the partSlicer settings
Why the order matters
The time goes on fixing the wrong thing.
Most of the time spent fixing 3D prints is not spent on the fix but on fixing the wrong thing. People start in the slicer because it has the most buttons, while the cause is a spool left open for two weeks.
The three checks on each card are taken straight from the quick-reference table in the troubleshooting article, in the same order. If a print that used to work no longer does, don't open the settings — look for what changed: the spool, how the bed was cleaned, the weather, a firmware update.
In what order should I troubleshoot a print?
Mechanical first (bed level, belts, filament path, nozzle), then material (moisture, diameter), then temperature and flow, then speed and acceleration, and only last the fine slicer settings. One variable at a time.
How do I know my filament is wet?
Listen for popping at the nozzle, watch for stringing that survives retraction tuning, and a rough surface from a spool that used to print smooth. Extrude 100 mm with the fan off: wet strand bubbles or curls and snaps.