ExtrudoWhy is my 3D print tpu under-extrusion and grinding?
Tpu under-extrusion and grinding is usually caused by flexible filament buckles inside the tube between the extruder and nozzle, especially with long retraction settings. Flexible filament grinds against the extruder gear or extrudes inconsistently, leaving weak or thin areas
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Quick reference
| Defect | Most likely cause | First thing to try |
|---|---|---|
| TPU under-extrusion and grinding | Flexible filament buckles inside the tube between the extruder and nozzle, especially with long retraction settings | Reduce or disable retraction |
What it looks like
Flexible filament grinds against the extruder gear or extrudes inconsistently, leaving weak or thin areas
Most likely cause
Flexible filament buckles inside the tube between the extruder and nozzle, especially with long retraction settings
How do I fix tpu under-extrusion and grinding? Step-by-step
- 1
Reduce or disable retraction
Lower retraction distance significantly (often under 2mm) or disable it — TPU doesn't handle long retractions well.
Done when: Filament feeds smoothly without buckling sounds
- 2
Print slower
Reduce print speed by 30-50% — TPU needs more time to extrude cleanly.
Done when: Extrusion looks even and consistent throughout the print
- 3
Reduce extruder tension slightly
Loosen the extruder's idler tension a little so it grips firmly without crushing the soft filament.
Done when: Filament shows light, even tooth marks without being flattened
Frequently asked
What causes tpu under-extrusion and grinding in 3D prints?
Flexible filament buckles inside the tube between the extruder and nozzle, especially with long retraction settings
How do I fix tpu under-extrusion and grinding on my printer?
Follow the step-by-step fix above, starting with "Reduce or disable retraction". Each step includes a "done when" check so you know whether it worked before moving on.
Is this fix confirmed by other makers?
This entry is part of Extrudo's seeded defect library. Confirmation counts appear once real users report the fix worked.
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