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Material not flowing right - HELP


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Posted · Material not flowing right - HELP

I find it difficult to judge the problem from your pictures, but in general I can say in the Ultimaker 2 printhead there is a teflon part that wears out. Have you replaced that in the last few years?

I had an ultimaker original with a similar part, and had to replace that every 2 years or so.

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    Posted · Material not flowing right - HELP

    If you do a cold pull ("atomic pull"), you can see if the teflon piece is worn out:

    - remove bowden tube,

    - insert a piece of filament into the nozzle,

    - heat up nozzle to printing temp,

    - push out a bit of material through the nozzle,

    - cool down nozzle untill room temp, then wait 10 min,

    - heat up nozzle to 60°C, and then gently wiggle, rotate and pull out the filament. (The older methods call for brute force pulling, but I don't like that. I pull very gently, by wiggling and rotating. Fingerspitzengefühl.)


    Now you should have a nice cone, showing the inside of your nozzle and teflon coupler. If there is a thick blob or ring at the lower part of the teflon coupler, it is worn out and needs replacement. Otherwise yit will cause underextrusion and uneven extrusion while printing.



    (The color changes are because I did the cold pulls to clean the nozzle while changing color.)


    The orange cone at the bottom is how it should look. The top and middle orange cones were pulled out a bit too soon, before they were fully cooled and solidified.




    The blue cone is still acceptable, althoug it begins to develop a ring in the teflon coupler. But the big ring in the white cone shows that that part of the teflon coupler is totally worn out. While printing, filament will get stuck in this area, causing uneven extrusion. So, that teflon coupler definitely has to be replaced.



    If the cone would show black sooth, do a few more cold pulls until the cone is clean. Otherwise black flakes will show up in the print.


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