3D Print Troubleshooting

Stringing (hairs between parts)Surface

What it looks like: Thin threads or cobwebs between separate parts of the print.

Why it happens

  • Nozzle too hot
  • Too little or too slow retraction
  • Wet filament
  • Slow travel moves

How to fix it

  1. Lower the nozzle temperature by 5–10 °C
  2. Increase retraction a little (direct drive 0.5–1.5 mm, Bowden 4–6 mm)
  3. Dry the filament
  4. Turn on “wipe” / “avoid crossing walls” in the slicer
  5. Make travel faster
Warping (corners lift)First layer

What it looks like: Corners of the part curl up from the bed; the bottom is not flat.

Why it happens

  • Plastic shrinks as it cools
  • Bed too cold or dirty
  • Drafts, no enclosure (ABS, ASA, Nylon)
  • Big flat parts with sharp corners

How to fix it

  1. Clean the bed with isopropyl alcohol or dish soap and water
  2. Raise the bed temperature by 5–10 °C
  3. Add a brim (5–10 mm)
  4. Use an enclosure and turn the fan down for ABS/ASA
  5. Round the sharp corners in the design
First layer doesn't stickFirst layer

What it looks like: Lines don't stick to the bed, get dragged around or the print comes loose.

Why it happens

  • Nozzle too high above the bed
  • Greasy bed (fingerprints)
  • Bed not level
  • First layer too fast

How to fix it

  1. Clean the bed
  2. Lower the Z offset in small steps (0.02 mm) until lines are slightly squished
  3. Level the bed / run auto bed leveling
  4. Print the first layer slower (20–30 mm/s)
  5. Use glue stick for tricky materials
Elephant footFirst layer

What it looks like: The bottom layers bulge out wider than the rest of the part.

Why it happens

  • Nozzle too close on the first layer
  • Bed too hot, the bottom stays soft

How to fix it

  1. Raise the Z offset a little
  2. Lower the bed temperature by 5 °C
  3. Use the slicer's “elephant foot compensation” (0.1–0.2 mm)
Under-extrusion (gaps, thin walls)Extrusion

What it looks like: Missing lines, gaps between walls, weak spongy parts.

Why it happens

  • Partly clogged nozzle
  • Printing too fast for the hotend
  • Temperature too low
  • Filament tangled or spool too tight
  • Worn extruder gear

How to fix it

  1. Heat up and do a cold pull, or change the nozzle
  2. Slow down or raise the temperature by 5–10 °C
  3. Check that the spool turns freely
  4. Clean the extruder gears
  5. Check flow / extrusion multiplier
Over-extrusion (blobby, too wide)Extrusion

What it looks like: Surfaces are rough and bulging, holes are too small, details are blurry.

Why it happens

  • Flow too high
  • Wrong filament diameter in the slicer
  • Extruder steps not calibrated

How to fix it

  1. Run a flow calibration and lower flow by 2–5%
  2. Check that the slicer uses 1.75 mm (or 2.85 mm) filament
  3. Calibrate e-steps / rotation distance
Layer shiftShape

What it looks like: Part of the print is suddenly moved sideways, like a staircase.

Why it happens

  • Nozzle hit the print (curled edges)
  • Loose belts or pulleys
  • Too fast / too high acceleration
  • Something blocked the print head

How to fix it

  1. Tighten the belts and pulley screws
  2. Lower speed and acceleration
  3. Turn on Z-hop when traveling
  4. Fix curling (more cooling for PLA)
Ringing / ghostingSurface

What it looks like: Ripples or echoes of edges on the surface next to corners and holes.

Why it happens

  • Vibrations at high speed and acceleration
  • Loose frame or belts
  • Printer on a wobbly table

How to fix it

  1. Lower acceleration and jerk
  2. Run input shaping / resonance compensation if your printer has it
  3. Tighten the frame and belts
  4. Put the printer on a heavy, stable surface
Z banding (horizontal lines)Surface

What it looks like: Regular horizontal stripes or bands up the side of the print.

Why it happens

  • Wobbly or dirty Z lead screw
  • Bed temperature swings
  • Layer height not matched to the Z motor steps

How to fix it

  1. Clean and lightly grease the Z screws
  2. Check the Z coupler and rollers
  3. Use layer heights that are multiples of 0.04 mm (e.g. 0.12, 0.16, 0.2)
Holes in the top surface (pillowing)Surface

What it looks like: Top surface has gaps or bumpy “pillows”.

Why it happens

  • Too few top layers
  • Too little cooling
  • Low infill under the top

How to fix it

  1. Use at least 4–5 top layers (0.8 mm+)
  2. Increase cooling for PLA
  3. Use a bit more infill or a “top surface” density setting
Blobs and zitsSurface

What it looks like: Small bumps on the walls, often in a line where each layer starts.

Why it happens

  • Layer start point (seam)
  • Pressure left in the nozzle
  • Wet filament

How to fix it

  1. Set the seam to “aligned” or “rear”
  2. Turn on “wipe” and coasting, calibrate pressure advance / linear advance
  3. Dry the filament
Layers split or crackStrength

What it looks like: Layers separate, the part breaks easily along the layer lines.

Why it happens

  • Temperature too low
  • Too much cooling (ABS, ASA, PETG)
  • Drafts
  • Layers too thick for the nozzle

How to fix it

  1. Raise the nozzle temperature by 5–10 °C
  2. Lower fan speed for ABS/ASA/PETG
  3. Use an enclosure
  4. Keep layer height below 75% of the nozzle size
Droopy overhangs and bridgesShape

What it looks like: Sloping parts sag, the underside is messy, bridges hang down.

Why it happens

  • Not enough cooling
  • Overhang steeper than ~45°
  • Too hot or too fast

How to fix it

  1. Increase fan speed
  2. Add supports for overhangs past 45–50°
  3. Lower temperature and speed for overhangs and bridges
  4. Turn the model so fewer parts hang in the air
Spaghetti (print came loose)First layer

What it looks like: A pile of tangled plastic instead of the model.

Why it happens

  • The part came off the bed
  • Tall thin part tipped over
  • Supports failed

How to fix it

  1. Fix bed adhesion (clean, brim, Z offset)
  2. Add a brim or mouse ears to small footprints
  3. Use stronger supports or change the orientation
Popping sounds, rough surfaceExtrusion

What it looks like: Crackling while printing, bubbles, fuzzy and matte surface, more stringing.

Why it happens

  • Wet filament (moisture boils in the nozzle)

How to fix it

  1. Dry the filament (see temperatures in the filament guide)
  2. Store spools in a sealed box with desiccant
Clogged nozzleExtrusion

What it looks like: Nothing or very little comes out; the extruder clicks.

Why it happens

  • Dust or burnt plastic
  • Heat creep (hotend fan not working)
  • Nozzle too close to the bed on the first layer

How to fix it

  1. Do a cold pull (heat, push, cool to ~90 °C, pull)
  2. Check that the hotend fan spins
  3. Replace the nozzle, it's cheap

Find your print problem by symptom and fix it.

How to use
  1. 1Type what you see or pick a category.
  2. 2Open a problem to see causes.
  3. 3Try the fixes from the top of the list.
FAQ
Where should I start?
Most problems come from the first layer, wet filament or temperature. Clean the bed, dry the filament and print a calibration cube.