Filament Sensor Lever hanging up on year-and-a-half old MK3S+
 
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[Solved] Filament Sensor Lever hanging up on year-and-a-half old MK3S+  

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HalfFinn
(@halffinn)
Active Member
Filament Sensor Lever hanging up on year-and-a-half old MK3S+

I have had my MK3S+ since September, 2021 and it has well over 2,000 hours of print time.  The filament sensor has always worked fine, but it quit working about a week ago, so I ordered and installed a new IR sensor board but that didn't fix the issue.  Before I replaced the cable too, I did more investigation and found that the lever is not consistently retracting when filament is removed.  Most of the time it retracts about half way, part of the time it does not retract at all, and occasionally it retracts properly.  I can manually move it back.  I thought I would ask in the forum before any more extensive tear-down.  Is this a symptom of dirt and dust, or is there something else that may be wrong? 

Thanks for any input on this.

Posted : 28/01/2023 4:10 pm
HalfFinn
(@halffinn)
Active Member
Topic starter answered:
RE: Filament Sensor Lever hanging up on year-and-a-half old MK3S+

OK, one other important piece of information.  I recently replaced the hot end.  The filament sensor problem probably coincides with that.  I'm betting that I screwed something up at that time, and I guess I'll do a tear down to see if I can find it.

Posted : 28/01/2023 4:55 pm
Stefan
(@stefan-3)
Estimable Member
RE: Filament Sensor Lever hanging up on year-and-a-half old MK3S+

a symptom of dirt and dust

To my experience, little very short pieces of  filament can get stuck in the chamber with the steel ball when unloading filament. They may block the movement of the ball and lever.

Posted : 28/01/2023 5:55 pm
HalfFinn
(@halffinn)
Active Member
Topic starter answered:
RE: Filament Sensor Lever hanging up on year-and-a-half old MK3S+

Thanks Stefan, I will check that. 

Posted : 28/01/2023 6:09 pm
RandyM9
(@randym9)
Honorable Member
RE: Filament Sensor Lever hanging up on year-and-a-half old MK3S+

Dust and debris will collect over time and cause issues. Best to disassemble and clean thoroughly. Pay attention to the screw tension on the lever pivot when you reassemble; if it’s too tight, the lever will bind and cause the issues you are seeing. You should be able to get a good sense of it before final assembly.

Cheers 

Posted : 28/01/2023 7:43 pm
HalfFinn
(@halffinn)
Active Member
Topic starter answered:
RE: Filament Sensor Lever hanging up on year-and-a-half old MK3S+

Thanks Randy.

Posted : 28/01/2023 8:01 pm
RandyM9
(@randym9)
Honorable Member
RE: Filament Sensor Lever hanging up on year-and-a-half old MK3S+

NP - See steps 5-7 in this link for reference:

https://help.prusa3d.com/guide/5-e-axis-assembly_169235

Cheers

Posted : 29/01/2023 3:27 pm
HalfFinn
(@halffinn)
Active Member
Topic starter answered:
RE: Filament Sensor Lever hanging up on year-and-a-half old MK3S+

So, after tearing the hot end assembly apart and examining the filament sensor system, I discovered that all I needed to do was to loosen the bolt slightly that the lever pivots on.  Apparently it had been OK before, but had maybe accumulated some dust and dirt just enough to create drag on the pivot.  Seems to be working fine now.  Thanks again for the feedback.

Posted : 29/01/2023 3:50 pm
RandyM9
(@randym9)
Honorable Member
RE: Filament Sensor Lever hanging up on year-and-a-half old MK3S+

Glad you got it sorted. I know, a pita to tear it down but good news that it was something basic.

Cheers

Posted : 29/01/2023 9:05 pm
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