Clogged nozzle: symptoms, causes and effect on printing

How a clog shows

With a complete clog, the printer pulls filament but nothing comes out, and the print starts to be laid down with empty layers. A partial clog shows earlier as under-extrusion: lines are thin, the printer clicks and the extruder skips.

In FDM the plastic is pushed through a very narrow opening, for example 0.4 mm, so even a small bit of dirt can block it.

Why a nozzle clogs

• Dirt and dust in the filament.
• Leftovers of a previous material with a different temperature.
• Damp filament that bubbles and carbonises, see filament moisture.
• Filament softening too high up in the hotend, see heat creep.
• A wrongly chosen temperature or an abrasive material that wears the nozzle, see hardened nozzle.

Another cause is often poor-quality or badly stored filament. A spool that is dusty or has an uneven diameter clogs the nozzle more often, see filament diameter.

How it is fixed

The easiest way is to clear the nozzle with cleaning filament at a higher temperature, or to poke it through mechanically with a thin needle. If that does not help, the nozzle has to be replaced, see nozzle and hotend. We do the printer maintenance.

For your order

If a nozzle clogs during printing, the part fails and has to be printed again, which can push back the lead time. We do not promise absolute freedom from faults. We photograph every batch before dispatch.