Under-extrusion

Under-extrusion occurs when the printer deposits less filament than expected, resulting in gaps between layers, thin or missing walls, and weak prints with visible holes in the surface.

Common Causes

1. Incorrect flow rate — The extrusion multiplier or flow rate is set too low
2. Partially clogged nozzle — Debris or degraded filament restricts flow
3. Filament diameter inconsistency — Actual filament diameter differs from slicer settings
4. Extruder gear slipping — The drive gear cannot grip the filament properly
5. Print speed too high — The extruder motor cannot keep up with the demanded feed rate
6. Low nozzle temperature — Insufficient heat makes filament harder to push through

Recommended Fixes

1. Calibrate your extruder steps/mm (e-steps) using a measured extrusion test
2. Clean or replace the nozzle to remove any partial blockages
3. Measure filament diameter with calipers and update your slicer profile
4. Check the extruder gear tension and replace worn drive gears
5. Reduce print speed by 10-20% and observe if gaps disappear
6. Increase nozzle temperature in 5°C increments until flow is consistent
7. Replace worn or low-quality PTFE tubing in Bowden setups