How to Cold-Pull clogged nozzle

If you find yourself with a clogged extruder and don't have any material coming out even if the drive gear is grabbing your filament you probably have a clog.

It can be a partial clog and a full clog, either way, there's a quick way to fix it without having to disassembly your machine, removing the nozzle and buying new parts.

It's called Cold-Pull, or as I like to do it; A Hot-Pull.

I made a better article about it all here: https://www.antonmansson.com/2017/02...logged-nozzle/ if you like to read, but also a visual guide here if that suits you better:

https://youtu.be/lixQgJUVNLc

The idea of it all is to follow 5 simple steps:
But to not waste your time, Here's how it's done!

1.
Unload your filament and make sure you have good access to you hotend. For bowden typ extruders, this might mean that you need to unplug the guide-tube.

2.
Heat the nozzle to around 200-220C. Make sure you start of cold, and as low as 190C for PLA-only printers.

3.
Insert a piece of white/bright nylon or a strong filament (PLA can do the trick). Push it down for 5-15 seconds or if you push filament out of the partially clogged nozzle.

4.
Pull back the filament out of the hot end and inspect the semi-molten end. This should have some dirt and gunk on it and not be completely molten. Usually you identify the dirt as some black dots and filament.

5.
Cut away the dirty part of the filament and repeat from step 3 until your filament comes out clean.

After around 5-20 repetitions you should now have a unclogged nozzle.

Please note that sometimes this isn’t enough, and we have to do a "severe cold pull", that puts more stress on the printer. The Cold-pull helps clean harder particles lodged and the end of the extruder.

A Cold-Pull is just that you cool down the printer after step 3, before doing step 4. This takes time and puts more stress on your machine, but is in general more efficient. for PTFE-lined extruders, it can damage the PTFE and dislocates it ( depending on your machines design).

Enjoy your clog-free nozzle!

/3D Print Tech Design
Anton Månsson