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3D printing troubleshooting

Clogged nozzle (not extruding)

Also known as: no plastic comes out, the extruder clicks or grinds the filament.

The symptom

No plastic comes out (or only a thin curly wisp), the extruder click-clicks skipping teeth or grinds the filament until it's chewed. Sometimes the print starts fine and dies a few layers in.

Sources for this page: Prusa Knowledge Base · Manufacturer Simplify3D · Technical guide

Causes and fixes, ranked by likelihood

  1. 1

    Charred residue inside the nozzle (typical after switching materials or long very-hot printing).

    Fix: Cold pull: heat up, push filament in (nylon or PLA), cool to ~90 °C and pull firmly — the plug comes out attached. Repeat 2-3 times. The cleaning needle helps with tip clogs.

    Source: Prusa Knowledge Base — Print quality issues ↗
  2. 2

    Heat creep: heat climbs the heatbreak, the filament softens too early and jams (prints dying mid-way).

    Fix: Make sure the hotend fan (the small one, not the part fan) ALWAYS spins and is clean. Reduce long, frequent retractions, especially with PLA.

    Source: Prusa Knowledge Base — Print quality issues ↗
  3. 3

    Temperature too low for that filament: not a clog, just plastic that can't melt at the requested rate.

    Fix: Check the SPOOL maker's range (not the material in general) and go to its upper half to rule this out.

    Source: Simplify3D — Print Quality Guide: Clogged Extruder ↗
  4. 4

    Brass nozzle eaten by abrasive filaments (CF, GF, glow): the bore deforms and jams.

    Fix: Switch to a hardened steel nozzle for abrasives. A nozzle is a cents-level consumable; an afternoon of clogs is not.

    Source: Simplify3D — Print Quality Guide: Clogged Extruder ↗
  5. 5

    Dirt riding in on the filament: dust collected on the spool, or particles in filled filaments (wood, glow) too big for the tip.

    Fix: Fit a dust filter before the extruder (a sponge with the filament through it works) and store spools in bags. With particle-filled filaments, use a 0.5-0.6 mm nozzle: they don't fit through a 0.4.

The material factor

PLA is the heat-creep king: it softens at such a low temperature that any poorly ventilated hotend jams it. PETG clogs by accumulation — it oozes, sticks to the tip and ends up carbonised inside. TPU never even reaches the nozzle: it buckles inside the extruder if you push fast. And fibre-filled filaments (CF/GF) attack on two fronts: particles that plug and abrasion that deforms brass.

hotend tools that help here

Material compatibility → If the clog came from experimenting with new materials, first check what your machine can actually print.

Related

FAQ

How often should a nozzle be replaced?
Brass with normal filaments: hundreds of hours no problem; inspect it if lines widen or under-extrusion appears. With abrasives, brass dies within tens of hours — go hardened steel from the start.
The extruder clicks but the nozzle is new — what do I check?
The click only says 'I can't push': it may be the nozzle, but also low temp, heat creep, badly seated PTFE, or a first layer squished so hard (Z-offset) it seals the tip against the bed.
It clogs every time I switch materials — what am I doing wrong?
Always purge at the temperature of the HOTTER of the two materials: pushing PLA at 210 °C into a nozzle with PETG leftovers means those leftovers never melt and slowly carbonise. Purge generously at the high temp, then drop to the working one.
Is torching the nozzle or a chemical bath worth it?
As a last resort on a brass one, sure; but a new nozzle costs cents and heroic cleaning costs an afternoon. Cold pull and needle first; if it won't clear, swap it and keep the old one for experiments.

Sources & references

This page is cross-checked against public manufacturer documentation and reference technical guides:

Still stuck? Back to the quick diagnosis or check which materials your printer can handle.