Under-Extrusion
Diagnose thin walls, gaps and missing filament caused by insufficient extrusion.
Under-extrusion occurs when less filament exits the nozzle than the printer expects.
Typical symptoms include gaps between lines, weak walls, incomplete top surfaces and visibly thin extrusion.
Start by checking the filament spool. Make sure it can rotate freely and that filament is not tangled.
Inspect the extruder. The drive gears should grip the filament firmly without grinding it away.
Then check for a partially blocked nozzle. Heat the nozzle and manually extrude filament. The filament should flow smoothly and consistently.
If the flow curls strongly sideways or comes out irregularly, the nozzle may contain debris.
Check that the slicer is configured for the correct filament diameter and nozzle size.
Temperature can also cause under-extrusion. If the nozzle temperature is too low for the filament or printing speed, the hot end may not melt material quickly enough.
Try increasing the nozzle temperature slightly or reducing print speed.
If the problem appears mainly during fast sections, the printer may simply be exceeding the hot end's maximum volumetric flow rate.
Common causes: partial nozzle blockage, tangled filament, low temperature, extruder slipping, excessive printing speed.