30 Common 3D Printing Problems and How to Fix Them

1. First Layer Not Sticking to Bed

A first layer that won't stick is usually caused by the nozzle being too far from the bed, a dirty bed or a bed that is too cool.

What it looks like: Your print starts fine but the first layer peels up, creating gaps or the entire print detaches from the bed.

Main causes:

• Nozzle too far from bed surface
• Bed temperature too low for your material
• Dirty or oily print surface
• Bed not properly leveled

Step-by-step fix:

1. Clean your bed thoroughly with isopropyl alcohol
2. Re-level your bed when both bed and nozzle are at printing temperature
3. Adjust nozzle height until you get slight resistance when sliding paper under it
4. Increase bed temperature by 5-10°C
5. Slow down first layer speed to 20-30 mm/s

Prevention: Clean your bed before every print and check bed level weekly.

2. Elephant Foot (Bulging Base)

Elephant foot is a bulge at the bottom few layers, caused by the nozzle squashing the first layer too hard or a bed that is too hot.

What it looks like: The bottom of your print is wider than it should be, creating a flared base that looks like an elephant's foot.

Main causes:

• Bed temperature too high
• Nozzle too close to bed
• First layer over-extruding

Step-by-step fix:

1. Lower bed temperature by 5-10°C
2. Raise nozzle slightly from bed surface
3. Reduce first layer flow rate to 90-95%
4. Add a small chamfer (0.2mm) to your model design

Prevention: Don't overdo the bed temperature. Better to have slight adhesion challenges than elephant foot.

3. Warping and Corner Lifting

Warping is corners or edges curling up off the bed as the plastic shrinks while it cools (full guide: 3D print warping causes and fixes).

What it looks like: Corners of your print curl upward, and edges lift off the bed as the print cools.

Main causes:

• Rapid cooling causing plastic shrinkage
• Poor bed adhesion
• Drafts around the printer
• Large flat surfaces without supports

Step-by-step fix:

1. Increase bed temperature by 10°C
2. Add a brim or raft to increase surface area
3. Eliminate drafts around your printer
4. For ABS: Use an enclosure or at minimum a cardboard windscreen
5. Disable part cooling fan for first 3-5 layers

4. Under-Extrusion (Missing Material)

Under-extrusion is the printer pushing out less plastic than the slicer expects, which leaves gaps, thin walls and weak infill.

What it looks like: Thin walls, gaps between perimeters, weak infill, or missing layers entirely.

Main causes:

• Partial nozzle clog
• Low printing temperature
• Printing too fast
• Wrong filament diameter setting
• Extruder tension too loose

Step-by-step fix:

1. Check filament diameter setting (1.75mm vs 3mm)
2. Increase nozzle temperature by 5-10°C
3. Reduce print speed by 20-30%
4. Increase flow rate to 105-110%
5. Check extruder gear tension
6. Clean or replace nozzle if problem persists

5. Over-Extrusion (Too Much Material)

Over-extrusion is the opposite: too much plastic, giving blobs, rough surfaces and oversized parts.

What it looks like: Blobs on surfaces, rough finish, dimensions larger than designed, or filament oozing from nozzle.

Step-by-step fix:

1. Reduce flow rate to 95-98%
2. Lower nozzle temperature by 5°C
3. Check that filament diameter is set correctly
4. Calibrate extruder steps if using new extruder

6. Stringing and Oozing

Stringing is thin hairs of plastic left between parts of a print when molten filament oozes from the nozzle during travel moves.

What it looks like: Thin strings of plastic between different parts of your print, like spider webs.

Main causes:

• Temperature too high
• Poor retraction settings
• Slow travel movements
• Wet filament

Step-by-step fix:

1. Lower printing temperature by 5-10°C
2. Increase retraction distance (try 4-6mm for Bowden, 1-3mm for direct drive)
3. Increase retraction speed to 40-60 mm/s
4. Enable "combing" to avoid crossing perimeters
5. Dry your filament if it's been exposed to humidity

7. Clogged or Partially Clogged Nozzle

A clogged nozzle is a full or partial blockage in the hotend that stops or starves the flow of filament.

What it looks like: No filament coming out, inconsistent extrusion, or clicking sounds from extruder.

Step-by-step fix:

1. Heat nozzle to printing temperature
2. Try pushing filament through manually
3. Perform "cold pull" cleaning method
4. Use cleaning filament if available
5. Remove nozzle and soak in acetone overnight
6. Use thin wire or nozzle cleaning needles
7. Replace nozzle if cleaning fails

Prevention: Regular maintenance cleaning and avoid mixing different material types without thorough cleaning.

8. Not Extruding at Start of Print

Not extruding at the start of a print means the nozzle moves but no plastic comes out for the first lines, usually because the hotend was not primed or the nozzle starts too close to the bed.

What it looks like: The first lines of the skirt or first layer are missing or very thin, then extrusion slowly appears.

Step-by-step fix:

1. Add a skirt or purge line so the nozzle is primed before the part starts
2. Re-check first-layer height (Z offset): a nozzle pressed against the bed cannot extrude
3. Check the drive gear has not stripped the filament
4. Clear a partial clog (see Clogged Nozzle above)

Source: Simplify3D print quality guide

9. Grinding Filament

Grinding filament is the extruder gear chewing a groove into the filament instead of pushing it, so feeding stops; it shows up as clicking from the extruder and plastic dust around the gears.

What it looks like: Clicking or skipping extruder, a flattened or chewed section of filament, extrusion that stops.

Step-by-step fix:

1. Reduce retraction distance and speed
2. Raise nozzle temperature 5-10 °C so plastic flows more easily
3. Lower print speed or maximum volumetric flow
4. Check for a partial nozzle clog
5. Cut off the ground section and reload the filament

Source: Simplify3D print quality guide

10. Stops Extruding Mid-Print

Stopping mid-print is extrusion that suddenly fails part way through a job while the printer keeps moving, typically from running out of filament, a stripped filament, a clog or an overheating extruder motor driver.

What it looks like: The print is fine up to a certain height, then nothing or only thin strands are deposited.

Step-by-step fix:

1. Check the spool did not run out or tangle
2. Inspect the filament at the drive gear for grinding
3. Clear the nozzle (cold pull or needle)
4. Make sure the electronics and stepper drivers are cooled
5. Use filament runout sensing if your printer has it

Source: Simplify3D print quality guide

11. Inconsistent Extrusion

Inconsistent extrusion is flow that varies from moment to moment, so some lines are thick and some thin, often from a tangled spool, a partial clog, poor filament or a worn extruder.

What it looks like: Some layers or lines look normal while others are thin or gappy, without a regular pattern.

Step-by-step fix:

1. Check the spool turns freely and the filament is not tangled
2. Clean or replace the nozzle
3. Avoid very low layer heights (below about 0.1 mm on a 0.4 mm nozzle)
4. Try a different, good-quality filament
5. Inspect the extruder gear and tension

Source: Simplify3D print quality guide

12. Layer Shifting

Layer shifting is a sudden horizontal offset between layers, usually from a skipped motor step caused by loose belts, a collision or too much speed.

What it looks like: Layers are offset horizontally, creating a stepped appearance on one side of the print.

Main causes:

• Loose belts
• Printing too fast
• Stepper motor overheating
• Mechanical obstruction

Step-by-step fix:

1. Check belt tension on affected axis
2. Reduce print speed and acceleration
3. Ensure print head moves freely by hand
4. Check for filament tangles
5. Verify stepper motor connections
6. Add cooling to stepper motors if overheating

13. Ringing and Ghosting

Ringing (ghosting) is a ripple pattern repeated after sharp corners, caused by frame and toolhead vibration at speed.

What it looks like: Ripple patterns or echoes around sharp corners and edges.

Main causes:

• Printer vibrations
• Loose mechanical components
• Too high acceleration/jerk settings

Step-by-step fix:

1. Tighten all frame bolts and connections
2. Check belt tension
3. Reduce print speed by 20-30%
4. Lower acceleration and jerk settings
5. Place printer on solid, heavy surface
6. Add dampening feet or concrete slab under printer

14. Z-Wobble and Banding

Z-wobble is a regular wavy pattern up the sides of a print, caused by a bent lead screw, a misaligned Z coupler or uneven layer heights.

What it looks like: Consistent wavy pattern running up the sides of prints, like a corkscrew effect.

Main causes:

• Bent Z-axis lead screw
• Misaligned Z-axis motor
• Loose Z-axis couplers

Step-by-step fix:

1. Check Z-axis lead screw for straightness
2. Ensure Z-motor is properly aligned
3. Tighten flexible couplers
4. Consider Z-axis stabilizers or guides
5. Lubricate Z-axis components

15. Poor Bridging

Poor bridging is plastic sagging when it spans a gap with nothing underneath, usually from too little cooling or too high a speed.

What it looks like: Drooping or sagging filament when printing across gaps without support.

Step-by-step fix:

1. Increase cooling fan to 100%
2. Reduce printing temperature by 5-10°C
3. Increase bridge speed to 150% of normal
4. Reduce bridge flow to 95%
5. Orient part to minimize bridge distances

Rule of thumb: Bridges longer than 15mm will likely need supports.

16. Support Structure Failures

Support failure is when supports break, fall over or fail to hold an overhang during the print.

What it looks like: Supports break away during printing, overhangs sag, or support removal damages the print.

Step-by-step fix:

1. Increase support density to 15-20%
2. Adjust support overhang angle (try 45-50 degrees)
3. Enable support interface layers
4. Use tree supports for better stability
5. Consider reorienting the model to need fewer supports

17. Curling or Rough Corners (Overheating)

Curling corners are overhangs and sharp corners that curl upward during printing because the plastic was not cooled fast enough to hold its shape, which is a sign of overheating.

What it looks like: Corners and overhang edges bend upward and look rough; small parts look melted.

Step-by-step fix:

1. Increase part cooling fan speed
2. Lower nozzle temperature 5-10 °C
3. Slow down or set a minimum layer time for small layers
4. Print several small parts at once so each layer has more time to cool

Source: Simplify3D print quality guide

18. Poor Surface Above Supports

A poor surface above supports is the rough, droopy underside of a supported overhang, caused by the gap between support and part or by sparse support interface.

What it looks like: The underside of overhangs is stringy, saggy or scarred where supports touched.

Step-by-step fix:

1. Enable support interface (roof) layers
2. Reduce the Z distance between support and part a little (balance against removability)
3. Lower layer height for overhang-heavy parts
4. Use a soluble or breakaway support material on multi-material printers

Source: Simplify3D print quality guide

19. Layer Separation and Delamination

Layer separation (delamination) is layers splitting apart because they did not fuse, usually from too low a temperature or too much cooling.

What it looks like: Layers splitting apart or visible gaps between printed layers.

Step-by-step fix:

1. Increase nozzle temperature by 10°C
2. Reduce cooling fan speed
3. Increase layer height slightly
4. Slow down print speed for better layer bonding
5. Check for drafts cooling the print too quickly

20. Rough Surface Finish

A rough surface finish is visible bumps, zits and uneven layer lines from inconsistent extrusion, seams or vibration.

What it looks like: Visible layer lines, bumpy texture, or inconsistent surface quality.

Step-by-step fix:

1. Reduce layer height for finer detail
2. Slow down outer perimeter speed
3. Fine-tune extrusion multiplier
4. Ensure consistent filament feed
5. Check nozzle for wear or damage

21. Dimensional Inaccuracy

Dimensional inaccuracy is parts printing larger or smaller than designed, so holes and press fits are wrong.

What it looks like: Parts that don't fit together, holes that are wrong size, or overall dimensions off.

Step-by-step fix:

1. Calibrate extruder E-steps
2. Print calibration cube and measure results
3. Adjust XYZ scaling in slicer if needed
4. Check belt tension and mechanical play
5. Consider horizontal expansion compensation

22. Blobs and Zits

Blobs and zits are small bumps on the outer wall where the nozzle starts and stops each loop, caused by pressure that builds up or drops at retraction points.

What it looks like: Small pimples or a visible line of bumps on the sides of the print.

Step-by-step fix:

1. Tune retraction, and try wipe or coasting
2. Avoid unnecessary retractions (combing / avoid crossing walls)
3. Set the seam position to aligned, rear or sharpest corner
4. Calibrate pressure advance (Klipper) or linear advance (Marlin)

Source: Simplify3D print quality guide

23. Pillowing (Gaps in Top Layers)

Pillowing is bumpy or holey top surfaces where the top layers sag between infill lines, because there are too few top layers, the infill is too sparse or the top layers are under-extruded or under-cooled.

What it looks like: Lumpy, quilted top surfaces with small holes showing infill below.

Step-by-step fix:

1. Increase top solid layers (aim for about 0.8-1 mm of top shell)
2. Raise infill percentage a little under large flat tops
3. Increase cooling for top layers
4. Fix any under-extrusion first

Source: Simplify3D print quality guide

24. Scars on Top Surface

Top-surface scars are lines dragged into the top of a print by the nozzle as it travels over it, usually from over-extrusion or no Z-hop.

What it looks like: Scratch-like lines or grooves across the top layer, sometimes with dragged material.

Step-by-step fix:

1. Reduce flow if the top is over-extruded
2. Enable Z-hop (vertical lift) on travel moves
3. Enable avoid crossing perimeters / combing within infill
4. Check the part has not curled up into the nozzle path

Source: Simplify3D print quality guide

25. Gaps Between Infill and Walls

Gaps between infill and walls are visible channels where the infill does not bond to the perimeters, from too little infill/perimeter overlap or printing too fast.

What it looks like: Thin gaps around the inside edge of walls, visible on top and bottom layers.

Step-by-step fix:

1. Increase infill/perimeter overlap (about 15-30%)
2. Slow down infill and solid infill speed
3. Print perimeters before infill if your slicer allows
4. Check for under-extrusion

Source: Simplify3D print quality guide

26. Gaps in Thin Walls

Gaps in thin walls are holes or missing sections in walls that are not a whole multiple of the extrusion width, so the slicer cannot fill them with full lines.

What it looks like: Thin features have a gap down the middle or are missing parts of the wall.

Step-by-step fix:

1. Enable gap fill and thin-wall detection (or Arachne variable-width walls)
2. Adjust wall thickness in your model to a multiple of the line width
3. Use a slightly wider or narrower extrusion width

Source: Simplify3D print quality guide

27. Weak or Stringy Infill

Weak infill is sparse internal structure that is stringy, broken or crumbly, usually because it is printed too fast or with lines too thin for the pattern.

What it looks like: Infill visible through gaps looks thin, broken or stringy, and parts feel weak or hollow.

Step-by-step fix:

1. Lower infill speed
2. Increase infill line width slightly
3. Try a stronger pattern such as gyroid, cubic or grid
4. Increase infill percentage for load-bearing parts

Source: Simplify3D print quality guide

28. Filament Moisture Problems

Wet filament is filament that has absorbed moisture from the air, which turns to steam in the nozzle and causes popping, stringing and weak parts.

What it looks like: Popping sounds during printing, steam from nozzle, poor surface finish, inconsistent extrusion.

Step-by-step fix:

1. Dry filament in dehydrator at appropriate temperature
2. Store filament in airtight containers with desiccant
3. Consider vacuum storage bags for long-term storage
4. Monitor humidity levels in printing area

29. Heat Creep

Heat creep is heat travelling up from the heater block into the cold side of the hotend, softening filament too early and causing jams.

What it looks like: Frequent jams, especially during long prints, inconsistent extrusion, or clicking from extruder.

Step-by-step fix:

1. Check hotend cooling fan operation
2. Ensure proper thermal barrier in hotend
3. Consider upgrading to all-metal hotend
4. Improve cooling around heat break
5. Check for heat block insulation touching cold end

30. Print Cracking and Brittleness

Cracking and brittleness are prints that split or snap easily, from poor layer fusion, wet or old filament, or the wrong material for the job.

What it looks like: Prints that crack easily, break apart during use, or show stress fractures.

Step-by-step fix:

1. Check filament age and storage conditions
2. Increase nozzle temperature for better layer bonding
3. Reduce cooling fan speed
4. Consider using an enclosure for better temperature control
5. Check for over-dried filament (yes, this can happen)