3D Printing Troubleshooting: 15 Common Problems and How to Fix Them

Every 3D printer user encounters problems. It does not matter whether you have a $200 Ender 3 or a $2,000 Bambu Lab X1 Carbon — at some point, something will go wrong. The difference between frustration and a quick fix is knowing what you are looking at and what to adjust.

This guide covers the 15 most common FDM 3D printing problems, what causes them, and exactly how to fix them. Bookmark this page — you will come back to it.

1. Stringing (Oozing)

What it looks like: Thin threads of filament stretched between parts of the model, like spider webs.

Causes:

• Nozzle temperature too high
• Retraction distance too short or retraction speed too slow
• Wet filament
• Travel speed too slow

Fixes:

• Lower nozzle temperature by 5–10°C. For PLA, try 195–200°C instead of 210°C.
• Increase retraction distance: 5–6 mm for Bowden, 1–2 mm for direct drive
• Increase retraction speed to 40–50 mm/s
• Increase travel speed to 150–200 mm/s
• Dry your filament at the appropriate temperature (PLA: 45°C for 4 hours, PETG: 65°C for 4 hours)
• Enable combing mode to keep travel moves within the model boundary

According to Sovol's stringing reduction guide, drying your filament is often the single most effective fix for persistent stringing.

2. Warping

What it looks like: The corners or edges of the print curl upward, detaching from the bed.

Causes:

• Material shrinkage as it cools (especially ABS, ASA, Nylon)
• Insufficient bed temperature
• Poor bed adhesion
• No enclosure (for ABS/ASA)
• Drafts or cold air in the room

Fixes:

• Increase bed temperature by 5–10°C
• Add a brim (8–15 mm width)
• Use an adhesion aid (glue stick, ABS juice)
• Enclose the printer for ABS and ASA
• Eliminate drafts — close windows and vents near the printer
• Reduce infill density (less internal material = less contraction force)

3. Layer Shifting

What it looks like: Layers are offset from each other horizontally, as if the top half of the print slid sideways.

Causes:

• Loose belts on X or Y axis
• Stepper motor skipping steps (current too low or speed too high)
• Nozzle collision with the print (causing the motor to skip)
• Loose pulleys on stepper motor shafts
• Overheating stepper motor drivers

Fixes:

• Tighten X and Y belts — they should be taut with a low-pitched twang when plucked
• Tighten the grub screws on the pulleys attached to stepper motors
• Enable Z-hop in your slicer (0.2–0.4 mm) to prevent nozzle collisions
• Reduce print speed and acceleration
• Check that stepper motor drivers have adequate cooling (add a fan if needed)

As Creality's ghosting and ringing guide notes, the quickest diagnostic is to check belt tension and pulley grub screws — these account for the majority of layer shift issues.

4. Under-Extrusion

What it looks like: Thin walls, gaps between lines, incomplete layers, visible infill through walls.

Causes:

• Partial nozzle clog
• Nozzle temperature too low for the material
• Filament diameter mismatch in slicer settings
• Worn or stripped extruder drive gear
• Filament tangled on the spool

Fixes:

• Perform a cold pull: heat the nozzle to 240°C, insert nylon filament, let it cool to 90°C, then pull firmly to extract debris
• Increase nozzle temperature by 5–10°C
• Verify filament diameter is set to 1.75 mm in your slicer (not 2.85 mm)
• Check the extruder drive gear for wear — if the teeth are smooth, replace it
• Increase flow rate by 2–5% as a temporary fix while you diagnose the root cause
• Unwind a few meters of filament and respool it to check for tangles

5. Over-Extrusion

What it looks like: Blobs, rough surfaces, bulging walls, filament squeezing out at corners.

Causes:

• Flow rate too high
• Nozzle temperature too high
• Filament diameter thicker than 1.75 mm
• E-steps not calibrated

Fixes:

• Reduce flow rate by 2–5%
• Lower nozzle temperature by 5°C
• Measure your filament diameter with calipers at multiple points and enter the actual value in your slicer
• Calibrate E-steps: extrude 100 mm of filament and measure what actually came out. Adjust steps/mm accordingly.

6. Elephant Foot

What it looks like: The first few layers are wider than the rest of the print, creating a bulge at the base.

Causes:

• Nozzle too close to the bed (Z-offset too low)
• Bed temperature too high
• Initial layer flow too high
• No cooling on initial layers (material spreads before solidifying)

Fixes:

• Raise Z-offset by 0.02–0.05 mm
• Lower bed temperature by 5°C
• Reduce initial layer flow to 95%
• Add a small chamfer (0.4–0.8 mm at 45°) to the bottom edge of your model in CAD
• Enable "elephant foot compensation" in your slicer (OrcaSlicer has this built-in)

7. Ghosting (Ringing)

What it looks like: Faint ripple patterns on the surface of the print, especially after sharp corners and direction changes.

Causes:

• Printing too fast with too high acceleration
• Loose belts causing vibration
• Wobbly frame or loose bolts
• Heavy printhead with too much inertia

Fixes:

• Reduce print speed to 40–60 mm/s and test
• Reduce acceleration to 500–1,000 mm/s²
• Reduce jerk to 5–10 mm/s
• Tighten all frame bolts
• Tighten belts to consistent tension
• Enable input shaping if your firmware supports it (Klipper, Marlin 2)
• Place the printer on a heavy, stable surface (a concrete paver works well)

According to Sovol's guide to fixing high-speed printing problems, input shaping calibration can eliminate ghosting at speeds of 200+ mm/s on properly configured Klipper printers.

8. Layer Separation (Delamination)

What it looks like: Visible gaps between layers, or layers that peel apart when force is applied.

Causes:

• Nozzle temperature too low (layers not bonding)
• Cooling fan too strong (especially for ABS and PETG)
• Layer height too large for the nozzle size
• Wet filament (moisture creates steam bubbles that weaken layer bonds)

Fixes:

• Increase nozzle temperature by 5–10°C
• Reduce cooling fan to 50% for PETG, 0–30% for ABS
• Ensure layer height is no more than 75% of nozzle diameter (0.3 mm max for a 0.4 mm nozzle)
• Dry your filament
• Increase wall overlap percentage in your slicer

9. Z-Banding (Consistent Horizontal Lines)

What it looks like: Regular, evenly spaced horizontal lines visible on the surface of the print.

Causes:

• Z-axis lead screw issues (binding, wobble, or inconsistent pitch)
• Inconsistent bed temperature
• Filament diameter variation
• Slicer layer height not aligned with lead screw pitch

Fixes:

• Clean and lubricate the Z-axis lead screw with PTFE or lithium grease
• Check for Z-axis binding by moving the axis by hand with the steppers disabled
• Use "magic numbers" for layer height — on printers with 8mm lead screws and 200-step motors, use layer heights that are multiples of 0.04 mm (0.12, 0.16, 0.20, 0.24, 0.28)
• Replace the lead screw coupler with a flexible coupler to absorb wobble

10. Blobs and Zits

What it looks like: Small bumps or pimples on the surface, often at the start/end of each layer.

Causes:

• Pressure buildup in the nozzle at layer change points
• Retraction settings not optimized
• Seam placement set to random (creates scattered zits)

Fixes:

• Set seam position to "aligned" or "rear" to concentrate zits in one hidden line
• Enable "wipe on retract" in your slicer (0.5–2 mm)
• Enable coasting (stops extrusion slightly before the end of a perimeter to relieve pressure)
• Fine-tune retraction distance and speed
• Reduce nozzle temperature by 5°C

11. Pillowing (Rough Top Surface)

What it looks like: The top surface has bumps, gaps, or a pillow-like texture instead of being smooth.

Causes:

• Not enough top layers to fully close over the infill
• Infill density too low (large gaps for top layers to bridge)
• Insufficient cooling

Fixes:

• Increase top layers to 5–6 (or 1.0 mm of solid top)
• Increase infill density to at least 20%
• Increase cooling fan to 100% for PLA
• Enable ironing in your slicer for a perfectly smooth top surface (adds time but produces excellent results)

12. Spaghetti (Print Detaches and Creates a Mess)

What it looks like: A tangled mess of filament instead of a recognizable model.

Causes:

• Print detached from the bed and the printer kept going
• Supports failed, causing overhangs to collapse
• Model has an issue (non-manifold geometry, too thin walls)

Fixes:

• Address bed adhesion (see our bed adhesion guide)
• Add or improve supports
• Use a print monitoring system (Obico, spaghetti detection in BambuStudio)
• Verify your model is watertight using the slicer's repair tools

13. Clogged Nozzle

What it looks like: Filament stops extruding mid-print, or extrusion becomes thin and inconsistent.

Causes:

• Debris buildup from carbonized filament
• Heat creep (heat travels up the cold end, softening filament too early)
• Mixing incompatible materials (e.g., PLA residue when switching to PETG)
• Incorrect retraction settings causing filament to jam

Fixes:

• Cold pull method: Heat to 240°C, push nylon filament through, cool to 90°C, pull firmly. Repeat 3–5 times.
• Acupuncture needle: Use a 0.35 mm needle to clear debris from a heated 0.4 mm nozzle
• Replace the nozzle: Nozzles are consumables. If cold pulls do not fix it, swap it. Brass nozzles cost $1–3 each.
• Check heat break and cooling fan: Heat creep is caused by insufficient cooling of the cold end. Ensure the heat break fan is running at full speed.

14. First Layer Not Sticking

What it looks like: The first layer does not adhere to the bed, gets dragged around by the nozzle, or comes up at the edges.

Causes:

• Z-offset too high
• Bed not level
• Bed surface dirty or worn
• Bed temperature wrong for material
• First layer speed too fast

Fixes:

• Lower Z-offset by 0.02 mm at a time until the first layer squishes properly
• Re-level the bed (or run auto-leveling)
• Clean the bed with isopropyl alcohol
• Match bed temperature to material (PLA: 60°C, PETG: 80°C, ABS: 100°C)
• Slow first layer speed to 20 mm/s
• Add a brim for extra grip

See our complete bed adhesion guide for an in-depth walkthrough.

15. Wet Filament Symptoms

What it looks like: Popping and crackling sounds during printing, rough surface texture, visible bubbles in the extruded lines, poor layer adhesion, excessive stringing.

Causes:

• Filament has absorbed moisture from the air. All filaments are hygroscopic to some degree, with Nylon and PETG being the worst offenders.

Fixes:

• Dry the filament before printing:

| Material | Drying Temperature | Drying Time | |----------|-------------------|-------------| | PLA | 45–50°C | 4–6 hours | | PETG | 65°C | 4–6 hours | | ABS | 80°C | 4–6 hours | | TPU | 50–55°C | 4–6 hours | | Nylon (PA) | 80°C | 8–12 hours |

• Use a dedicated filament dryer (Sunlu S2, eSun eBOX, PrintDry)
• Store filament in sealed bags with desiccant packets
• Print from a dry box for hygroscopic materials

Troubleshooting Flowchart

When you encounter a print failure, work through this diagnostic process:

1. Is the first layer good?
   NO → Fix bed adhesion (Problem #14)
   YES → Continue

2. Is the print detaching mid-print?
   YES → Warping (#2) or Spaghetti (#12)
   NO → Continue

3. Is the surface rough or bumpy?
   Blobs at seams → Zits (#10)
   Ripples at corners → Ghosting (#7)
   Rough top → Pillowing (#11)
   Random bumps → Over-extrusion (#5) or wet filament (#15)

4. Are layers misaligned?
   YES → Layer shifting (#3)
   NO → Continue

5. Are there gaps or thin spots?
   YES → Under-extrusion (#4) or clog (#13)
   NO → Continue

6. Are there strings between parts?
   YES → Stringing (#1)
   NO → Your print might actually be fine!

Prevention Is Better Than Fixing

Most print failures are preventable with good habits:

1. Keep filament dry — store it properly and dry it before printing
2. Clean your bed before every print with IPA
3. Maintain your printer — tighten belts, lubricate rails, clean nozzles monthly
4. Use quality filament — cheap filament with poor diameter tolerance causes endless problems
5. Calibrate regularly — run flow rate and e-step calibration with each new filament

Find Test and Calibration Models

The best way to diagnose and fix printing issues is with purpose-built test models. Search for calibration cubes, temperature towers, retraction tests, and overhang tests on 3DSearch. Having a library of go-to test prints makes troubleshooting faster and more systematic.

Final Thoughts

Every problem on this list has a fix. 3D printing troubleshooting is a process of elimination — identify the symptom, narrow down the cause, and adjust one setting at a time. Resist the urge to change multiple settings at once, because then you will not know which change actually fixed the problem.

Save this guide, and the next time a print fails, you will know exactly where to look.

Happy printing!