Clearing a blocked nozzle without swearing

A cold pull tells you what went wrong as well as fixing it — the shape of the plug is the diagnosis.

The cold pull

• Heat to 220°C and push filament through by hand
• Let it cool to about 90°C
• Pull firmly and steadily — it should come free with a clean tip
• Look at the tip: a clean cone means grit, a stringy mess means heat creep

Check the hotend fan

If the small fan pointed at the heatsink has stopped, heat travels up the throat and softens filament above the melt zone. The print jams part-way through, every time, at roughly the same point. It is missed constantly.

Abrasive filament

Carbon fibre, glow and wood-filled filaments will wear a brass nozzle out in hours. Fit hardened steel before you run PLA-CF, not after.