Performing a "Cold Pull"

If the hot end is reaching target temperature but no filament is extruding, it is a possibility that there is a build up of material or a foreign object that is clogging the nozzle or hot end. Performing several cold pulls will remove this unwanted material and possibly fix the clog. At the bottom of this article is a video that explains this procedure.

Using Nylon (preferred):

1. Set the nozzle to the printing temperature for the material you currently have in the hot end.
2. Verify the nozzle has reached target temperature, then remove the filament from the hot end
3. Insert an 12 inch long piece of nylon filament, preferably in natural or white color so you can see confirmation of contaminants being removed.
4. Heat up the hot end to the printing temperature of the nylon (usually around 240C).
5. Verify the nozzle has reached target temperature, then set it to cool down to 80C.
6. Allow the hot end to cool until it reaches the set temperature of 80C.
7. Once this temperature is reached, be prepare to start pulling the filament upwards and out from the extruder.
8. Set the hot end to heat back up to the printing temperature of nylon, then start pulling the filament upwards and out from the extruder. The filament will be stuck at first, but as it begins to soften, it will release from the hot end, bringing with it the debris from the hot end and nozzle.
9. Insert more clean nylon filament, and then repeat this process 3-5 times until the nylon filament pulled from the nozzle is free of any particulates. 

Using the same material filament:

1. Trim the filament six inches above where it enters the extruder. This length of material is needed to grab and pull the filament from the extruder in the next steps. 
2. Set the nozzle to the printing temperature for the material you are using.
3. Verify the nozzle has reached target temperature, then set it to cool down to 80C.
4. Allow the hot end to cool until it reaches the set temperature of 80C.
5. Once this set temperature is reached, be prepare to start pulling the filament upwards and out from the extruder.
6. Set the hot end to heat back up to the printing temperature of the material you are using, then start pulling the filament upwards and out from the extruder. The filament will be stuck at first, but as it begins to soften, it will release from the hot end, bringing with it the debris from the hot end and nozzle.
7. Insert more clean filament, and then repeat this process 3-5 times until the filament pulled from the nozzle is free of any particulates. 

Video demonstration of a cold pull

Questions or concerns? Reach out to our support team at support@re:3D.org or open a support ticket.