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MK3S+ upgraded extruder - filament sensor issue  

New Member
MK3S+ upgraded extruder - filament sensor issue

Hi all,

  I've finished my upgrade from MK3S to MK3S+.  It works very well except the filament sensor.

  Everything is correctly connected and the sensor itself is not faulty, but the small arm (repulsing magnets) which breaks the sensor is marginally out meaning a hit and miss sensor.  I have tried everything in the troubleshooting below but it is still not right:

  If the filament has the bend from being reeled one way it works, if it is against the bend it doesn't.

  I'm not sure what else I can do here other than live with a feature of my printer not working, something I never had any issue with before the upgrade.

  Any suggestions... or other workarounds out there?

  A side note, the prints after upgrade are exactly as before.  My reason for upgrade was an issue with thermal runaway - unless I turned down the fan speed on the prints.  This upgrade fixed the problem... pity I have this new issue to replace it.



Posted : 06/01/2021 9:40 pm
RE: MK3S+ upgraded extruder - filament sensor issue

Are you using the Red Filament Sensor?



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Posted : 07/01/2021 12:49 am
New Member
Topic starter answered:
RE: MK3S+ upgraded extruder - filament sensor issue


  Yes it is the red filament sensor.

  Anyway, I resolve the issue thanks.. was very frustrating.

  I believe that using the textured sheet for the FS lever, it made the part somewhat glossy and reflective which stopped the sensor from working properly.  I don't actually know this 100%, but dismantling the extruder, the original print still had the issue.  The newer smooth sheet print worked straight away.  There was visually nothing different shape wise or how it was installed.

PETG - textured Vs smooth

Kudos to Prusa though.  This extruder is far more helpful to work on.  Remove the fans, 4 screws and you can pretty much interact/swap out any of the internal parts.

I'm glad I done the upgrade... could of lived without it, but I enjoyed the journey, it was similar to the original build where you get to the end and go.. omg, it actually works.

Equally I damaged the print fan by over tightening the screws on day 1 where it cracked the wrong size holes.  This with my thermal runaway issue meant it was worth the effort.

Posted : 07/01/2021 8:00 pm