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How to do a Cold-Pull and fix your clogged nozzle

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    How to do a Cold-Pull and fix your clogged nozzle

    If you end up with a clog in your extruder i've found many tend to just replace the nozzle and do a lot of work, when all they might need to do is some hot-pulls/cold-pulls. Just get the particles/clogged material out and spend a few minutes doing it instead of breaking down your machine.

    This is done by doing what's called a Cold-Pull. I tend to do another version, called Hot-Pull, where you do it more rapidly, but more often.

    I've made a longer article about it and a video here that i'd like to share





    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. 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. Usually 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).

    Hope this helps and solves many small problems for you!
    Using the Cold-Pull or Hot-Pull method, you can avoid buying a new nozzle. Here's how to Cold-Pull a clogged nozzle.
    Last edited by 3DprintTechDesign; 02-20-2017, 09:32 AM. Reason: Added text and corrected spelling

    #2
    I just got three nozzles cleared that this did not work for. I took them off, put them in a 500 degree oven (Fahrenheit), with the large opening down.
    The clogs melted and ran out of the nozzle. I used steel strings from an electric guitar to push out any remaining gunk. The .009 and .011 inch strings
    work for my 0.4mm nozzles

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