====== Nozzle Clearing ======
{{ ::3mm_nylon_success_2.jpg?800 |A clean nozzle is a happy nozzle}}
There are several reasons you may need to clean out your nozzle. Foreign particles, filament contaminants, accumulated dust,
overheated and scorched plastic can all become lodged in your nozzle and prevent smooth extrusion. Scorched plastic can also stick to
the sides, creating resistance for the plastic traveling past without actually blocking the nozzle. This procedure for clearing your
nozzle should be performed any time you are unable to extrude plastic, and periodic cleaning by this method is not a bad idea.
In the early days of home 3d printing, it was much more difficult to clear nozzles. It often required disassembling them and heating
with a torch to remove plastic to get obstructions out, but this results in more scorched plastic and risks damaging some of the
parts if improper force is applied (stripped threads, nozzles breaking at the narrow point between the threads and the inner bore,
etc.) or nozzles being reinstalled without a proper seal. Some people also soak their nozzles in a solvent, but it can take some time
for solvents to completely penetrate the plastic inside the nozzle, and even once saturated with a solvent, the plastic can be
viscous and difficult to remove entirely.
The safest and most effective way to completely clear the plastic from a nozzle, taking any contaminants with it, is what I call a
“cold pull”. The idea behind the cold pull is to pull the filament out of a nozzle at a temperature cool enough to keep it in one
piece (rather than leaving molten plastic in the hot zone), but still warm enough to allow the plastic to stretch enough to pull away
from the sides of the barrel so that it doesn’t seize up entirely. This is easiest to perform with a polished-smooth stainless steel
barrel, with those that have a PTFE liner all the way to the end coming in second, because nozzle pressure can slightly compress the
softer PTFE and create a plug that will be difficult to pull out.
