About 5 hours into a print last night, the filament stopped extruding leaving the model unfinished.

On investigation, I saw that the filament had stopped feeding. I can see marks on the filament left by the wheel that feeds it through the tube. The marks stop with a black mark. Does the black mark suggest a reason why the printer stopped printing?

I am using an Anycubic Mega S with 3dJake EcoPLA.

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  • 2
    $\begingroup$ Probably need information on what printer/extruder you're using, as it may be related. $\endgroup$
    – Zeiss Ikon
    Dec 30, 2021 at 18:52
  • 1
    $\begingroup$ It would be interesting to see the end of the filament that was in the extruder. I see a black spec further down the filament too. It looks like your gear is dirty and depositing grit on the filament that might be collecting in the nozzle and clogging it. $\endgroup$
    – user10489
    Dec 31, 2021 at 1:45
  • 1
    $\begingroup$ could be black PLA or grease... $\endgroup$
    – Trish
    Dec 31, 2021 at 20:44
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    $\begingroup$ I think it is important to figure out what the black residue is and where it is coming from. $\endgroup$
    – user10489
    Dec 31, 2021 at 23:32
  • 2
    $\begingroup$ Does your filament drive have a rubber-tyred wheel, or a metal wheel? $\endgroup$
    – Criggie
    Jan 1, 2022 at 1:46

1 Answer 1


2 possibilities occur:

  • Grease/dust has contaminated your filament somehow, and the extruder's drive wheel is not gripping it. The rest of the printer would have "air-printed" Maybe the filament was pre-dirty and this is the point it stopped.

  • Stoppage - something blocked up the hotend and the filament resisted being pushed in. Perhaps the hotend cooled down and filament solidified, or there's a real blockage in there.

If you had a camera on the printer, you might be able to review timelapse footage and see if anything happened.

Right now I'd suggest you discard that length, refit the same filament, and print something small, just to make sure its still working. You might choose to aim any timelapse camera directly at the filament drive wheel or just watch it.


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