How to clean a clogged nozzle using the cold pull method?
Cold Pull is a method of cleaning the nozzle from dirt without wringing it out.
To perform it, we will need PLA. You will also need to disconnect the filament drive. The best way will be to unscrew the tensioner sprocket or loosen the motor.
We take out the old filament or its remnants, load the PLA, and heat the extruder to 270 degrees Celsius.
Once this temperature is reached, we set it to 0 degrees, and push the filament out by hand. The idea is to make sure the PLA thoroughly fills every gap in the nozzle and gets in between the debris. In the photo you can see the exact imprint of the inside of the nozzle along with the 0.4mm hole.
After the extruder reaches room temperature, we warm it up to 80 and here very important! The moment this value shows on the display (or 79), you should immediately pull out the filament while keeping an eye on it with your other hand not to damage the extruder head.
DO NOT jerk, pull out in a smooth motion. There is a possibility of PLA breaking off, in which case we repeat the procedure. Also if we do not manage to extract all the impurities.