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

## 1. Stringing **Symptom**: Thin plastic hairs between parts. **Fix**: Increase retraction (4–7 mm for Bowden, 1–2 mm for direct drive). Increase travel speed. Lower print temperature by 5°C. Enable combing. ## 2. Layer Shifting **Symptom**: Print layers are offset — the model looks sheared sideways. **Fix**: Tighten belts (both X and Y). Check stepper motor currents. Reduce print speed. Check for mechanical obstruction. ## 3. Under-Extrusion **Symptom**: Gaps in walls, missing layers, weak prints. **Fix**: Increase print temperature. Check for partial clog (cold pull). Increase flow rate 5%. Check extruder grip on filament — worn gear or loose tensioner. ## 4. Over-Extrusion **Symptom**: Blobs, lumpy surfaces, walls too thick. **Fix**: Reduce flow rate 5%. Calibrate E-steps. Reduce temperature. ## 5. Clogged Nozzle **Symptom**: No extrusion or severely under-extruded. **Fix**: Heat to print temp, manually push filament. Cold pull at 90°C (PLA). Needle clear. Replace nozzle ($2–5). ## 6. Bed Adhesion Failure **Symptom**: Print lifts mid-print. **Fix**: See first layer guide. Clean bed with IPA. Add glue stick or Magigoo. Add brim in slicer. ## 7. Spaghetti / Print Failure **Symptom**: Filament deposited randomly in mid-air. **Fix**: First layer didn't adhere. Fix bed adhesion first. Reduce speed. Check cooling fan. ## 8. Elephant Foot **Symptom**: First layer bulges outward beyond the model. **Fix**: Raise Z-offset slightly. Reduce bed temperature. Reduce first layer flow to 95%. ## 9. Ghosting / Ringing **Symptom**: Wave patterns on surfaces near sharp corners. **Fix**: Reduce print speed. Tighten belts. Enable Input Shaper (Bambu, Klipper, Marlin 2.x). ## 10. Poor Bridging **Symptom**: Drooping or spaghetti on horizontal spans. **Fix**: Reduce bridge speed to 20–30 mm/s. Increase cooling fan to 100% for bridges. Reduce temperature 5°C for bridging. ## 11. Overheating / Drooping **Symptom**: Upper layers droop or melt on small cross-sections. **Fix**: Increase cooling fan. Reduce print speed. Print two copies simultaneously (printer moves away to cool). ## 12. Delamination **Symptom**: Layers split apart. **Fix**: Increase nozzle temperature 5–10°C. Reduce layer height. Reduce cooling on structural prints. ## 13. Cracked Nylon / ABS **Symptom**: Inter-layer cracking during or after print. **Fix**: Dry filament — Nylon especially absorbs moisture and cracks when wet. Increase temp. Enclose printer. ## 14. Inconsistent Extrusion **Symptom**: Variable line width, some lines thin/thick. **Fix**: Dry filament. Check PTFE tube for kinks. Check bowden coupling grip. Check extruder for worn gear. ## 15. First Layer Too High **Symptom**: Lines are round beads, not squished, don't stick. **Fix**: Lower Z-offset in 0.05 mm steps while first layer prints until lines flatten slightly.