Nozzle Maintenance Guide
Clearing a clog, keeping a nozzle printing cleanly, and knowing when it's actually time to replace it.
The cold pull
1. Heat the nozzle to the filament's normal printing temperature and manually feed filament through until it extrudes cleanly, then heat an extra 10–20°C above that to soften any built-up residue.
2. Let the temperature drop to roughly 90–100°C for PLA (adjust upward slightly for higher-temp materials) — cool enough for the filament to solidify and grip the inside of the nozzle, but not so cool it seizes rock solid.
3. Pull the filament straight out firmly and steadily. A clean pull brings a thin tapered strand out with it — if that strand shows debris, discoloration, or a rough torn end, repeat with fresh filament until it comes out clean.
Why cold pulls work
Solidifying the filament partway lets it grip and drag out carbonized residue and debris stuck to the nozzle's inner walls that would otherwise stay behind — pulling filament out fully molten just leaves that residue in place since there's nothing for it to stick to on the way out. Nylon or a dedicated cleaning filament pulls more residue than PLA due to how it solidifies, which is why some printer manufacturers recommend it specifically for this process even if you don't otherwise print in it.
Preventing clogs before they happen
Most clogs trace back to moisture-absorbed filament (nylon and PETG especially) off-gassing inside the hot end, leftover residue from a filament swap without a cleaning pull in between, or printing at a temperature too low for the material to fully melt through the nozzle. Dry hygroscopic filaments before use, and do a quick cold pull whenever switching between very different materials (especially into or out of nylon).
When to just replace the nozzle
Brass nozzles wear over time, especially with abrasive filaments (anything with carbon fiber, glass fiber, wood, or metal fill) — a worn nozzle develops a slightly enlarged or oval orifice that causes persistent under-extrusion no cold pull will fix, since the metal itself has eroded rather than being blocked by debris. If under-extrusion continues after a clean cold pull and correct temperature/flow settings, the nozzle itself is the likely culprit, especially after printing much abrasive filament.