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[Solved] Printer stops to unload filament  

New Member
Printer stops to unload filament

Hi, I've been printing for a couple of months now with no big issues, but now that I've started to run longer prints I have encountered the following issue:

During printing the printer will suddensly stop in place, and I can see the "cogs" that feed the filament running in the opposite direction as if unloading the filament. Then they briefly will load again, but after a couple of seconds the head will move to the side and the printer will sound an alarm with the message: "Please press the knob to unload filament". After manually unloading and loading the filament the print usually resumes without issue.

This used to only occur now and then, but lately it occurs every few minutes, even during first layer calibration etc.

Does anyone have an idea what causes this and how I can resolve it?

Much obliged,


Posted : 14/03/2020 10:12 am
Prominent Member
RE: Printer stops to unload filament

You do not write which printer you have (MK3 or MK3S), but this is how MK3 can behave for certain types of filaments that the filament sensor is difficult to detect.
For these filaments it helps to temporarily switch off the filament sensor. Do not forget to activate the sensor again when changing filaments.

Bear MK3 with Bondtech extruder...
Posted : 14/03/2020 10:43 am
akylos58 liked
New Member
Topic starter answered:
RE: Printer stops to unload filament

Oh, sorry! I wasn't thinking this might be a MK3 specific issue. It is indeed a MK3.
I have been reading the forums for the last couple of hours, and I've seen similar-but-not-exactly the same problem, but it all revolved around the IR sensor giving issues indeed. I have been using the same types of filament since forever though, so I wonder why it only now became an issue.

I had already set up a new attempt with the sensor off, and it is running fine so far. Let's see how this goes.

Thank you for the response!

Posted : 14/03/2020 11:52 am
RE: Printer stops to unload filament


Sometimes dust builds up inside the mk3 sensor housing. Try air duster. There is a small hole in the midske of tge bondtech doir hinge whele you can stick the air duster tube. Its normally blocked off with a plastic plug...

Or remove the sensor and clean it...

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 14/03/2020 1:20 pm