Filament stuck in PTFE tube all the time with new Hot end

  • Hey there,

    So I have a problem I just can’t solve on my own.
    I have an Ender 3 pro and I had to change the hot end recently due to my own clumsiness. But now there is an issue that drives me nuts.

    The Filament flow just stops.

    printing.jpg As you can see the I can print the raft nice and pretty (only looks a little wobbly because I peeled it off the warm bed) and then the Filament just stops. If I print the same file without a raft and change nothing it will print about 60% and then the flow stops. If I pause the print and restart the problem will stay, if I stop the print and restart the Raft will be printed again before the problem is there again (if the filament didn’t have the chance to cool down too much).

    It seems like the Filament is piling up in the hot end in the PTFE tube and just can’t be pushed through anymore after a while. Then I always have to remove it forcefully by hand which can be quite difficult.


    The hotend and the nozzle are not clogged at all, it always seems to be in the tube end. I even tried to let it print “in the air” and without a nozzle if you know what I mean to see if there might be an issue in thosep arts, but nope. Nothing

    So here is what I already tried to do (and obviously nothing helped):

    • Trying different Filaments (PLA and ABS)
    • Printing with different temperatures, I used 5C° steps from the lowest to the highest temperature
    • list itemreplacing the PTFE tube and making sure it’s cut and aligned perfectly
    • list itemreplacing the nozzle
    • list itemdifferent Slicing softwares, just to make sure (creality slicer, Ultimaker Slicer, Prusa Slicer)
    • list itemdifferent g-codes
    • list itemdifferent retraction speeds/ lengths (not even a little difference here no matter what I do)
    • list itemturned fan off completely, 50% and 100%
    • list itemmaking sure the hot end is hot (yes it is hot, but maybe still defect somehow?)
    • list itemmaking sure the curve of the PTFE tube is gentle and not too tight
    • list item different printing qualities and speeds

    What else can I try to fix it? I’m getting haunted by the ‘click click’ sounds whenever I try a new idea that might help me.


  •  You appear to have tried a lot of different things without focusing on anything specific. Stay focused on the filament path. Stick with PLA for this testing and use a PLA that is fairly new (not old and brittle). Use a "normal" PLA, not one with textures, silk, or other things that will cause jams. 
     With filament loaded in the printer, move the Z axis up to somewhere around 75-100mm too get it a ways off the bed. Heat the PLA filament up to 215C. Once temp is up, press on the extruder arm to relieve tension between the pully and the gear, now PUSH on the filament. This should cause filament to extrude out of the nozzle. If it doesn't, something is blocking or pinching your filament path. 
     Disconnect the bowden tube connector that is on top of the hot end. Make sure the filament smoothly goes through the ptfe tube between the extruder and the end of the tube. Filament should go through sm oothly with very little pressure. IF it goes through there smoothly, then the problem is in the hotend somewhere.
     With the Bowden tube connector removed from the top of the hotend, remove the PTFE tube that is inside the hotend. If you have trouble with this remove the nozzle and push the tube from the top. It should go all the way through. Make sure the PTFE tube inside the hotend allows filament to go through it smoothly with no binding or pinching. If these are too long, they can pinch the filament at one end or the other. That tube length is very precuse. Too long and it pinches, too short and it leaves a void which fills with plastic, causing your filament to get stuck. IF that tube is clear and filament goes through smoothly , and it is the correct length, clean and/or replace your nozzle. Make sure your new nozzle has the correct diameter hole. Check with a proper size needle. Reassemble the hotend, put the bowden tube on and once again, trry the manual pushing the filament through. Filament should should flow smoothly through the nozzle. 

    Good Luck!

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