ExtrudoWhy is my 3D print over-extrusion?
Over-extrusion is usually caused by the flow rate or filament diameter setting is telling the printer to push out more plastic than it should. Too much plastic is coming out, leaving blobby surfaces, oversized dimensions, or rough walls
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Quick reference
| Defect | Most likely cause | First thing to try |
|---|---|---|
| Over-extrusion | The flow rate or filament diameter setting is telling the printer to push out more plastic than it should | Lower your flow percentage |
What it looks like
Too much plastic is coming out, leaving blobby surfaces, oversized dimensions, or rough walls
Most likely cause
The flow rate or filament diameter setting is telling the printer to push out more plastic than it should
How do I fix over-extrusion? Step-by-step
- 1
Lower your flow percentage
Reduce your slicer's flow rate by 3-5% and reprint a small test — most over-extrusion issues resolve around 92-98% flow.
Done when: Surface looks smoother with less blobbing
- 2
Double check filament diameter setting
Measure your filament with calipers in a few spots and make sure the average matches the diameter set in your slicer (usually 1.75mm).
Done when: Slicer setting matches your measured filament diameter
- 3
Calibrate extruder steps
Run an extruder calibration (mark filament, extrude 100mm, measure actual output, adjust steps/mm accordingly).
Done when: Extruder moves exactly 100mm of filament when asked to
Frequently asked
What causes over-extrusion in 3D prints?
The flow rate or filament diameter setting is telling the printer to push out more plastic than it should
How do I fix over-extrusion on my printer?
Follow the step-by-step fix above, starting with "Lower your flow percentage". 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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