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Mk3s filament sensor not working  

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Nyxjen
(@nyxjen)
New Member
Mk3s filament sensor not working

So I installed my Mk3s upgrade parts last week and it's all been working flawlessly except for the filament sensor. Under the sensor panel it always shows 0 no matter what and I can't print unless I disable it. The magnets are installed properly and always repel. The arm can move freely as well as the steel ball. I'm not sure the issue

Posted : 22/03/2019 2:08 am
Twisted Metal Prototyping
(@twisted-metal-prototyping)
New Member
Re: Mk3s filament sensor not working

Have you tried the filament sensor calibration procedure?

Posted : 24/03/2019 3:07 pm
swiftbow
(@swiftbow)
Eminent Member
Re: Mk3s filament sensor not working

Double check the connection to the board. If you accidentally installed to the top row, it will read zero. Make sure it is connected to the bottom row.

Posted : 24/03/2019 5:56 pm
Wydra91
(@wydra91)
Active Member
Re: Mk3s filament sensor not working


Have you tried the filament sensor calibration procedure?

I've been following this post because I'm having similar issues, how do I go about doing that?

Posted : 24/03/2019 6:31 pm
holmes4
(@holmes4)
Estimable Member
Re: Mk3s filament sensor not working

In addition to making sure the sensor connector is in the bottom row, also make sure it is the right way around! Pay attention to the wire colors. (See purple arrow):

https://d17kynu4zpq5hy.cloudfront.net/igi/prusa3d/XFbWxwIiDqReKZXA.medium

Posted : 24/03/2019 7:55 pm
keegan.m
(@keegan-m)
New Member
Re: Mk3s filament sensor not working

I just upgraded my MK3 to the MK3S extruder (No MMU) last night and have also been seeing similar problems. I've done a bit of troubleshooting but haven't been able to solve it. Here's what I've figured out:

  • I cannot auto load filament

  • I cannot start a print with the filament sensor enabled - the unit acts as though no filament is inserted

  • I did a continuity check of the cable going from the Einsy board to the sensor board.

  • I measure 5V power to ground on the sensor

  • The output pin of the sensor board measures 5V with no filament inserted and 0V with filament inserted (seems to be correct). I checked this both on the sensor board and then by measuring on the connector at the Einsy board.

  • I connected the sensor board to the bottom row of the P3 header with the red pin on the right as shown in the documentation

  • I'm running the 3.6.0-2069 image for the MK3S
  • Posted : 25/03/2019 12:27 am
    Twisted Metal Prototyping
    (@twisted-metal-prototyping)
    New Member
    Re: Mk3s filament sensor not working



    Have you tried the filament sensor calibration procedure?

    I've been following this post because I'm having similar issues, how do I go about doing that?

    I believe it's part of the new manual. You can see the status of your sensor on LCD control. 0 is no filament 1 is filament . I have mine switching somewhere in the middle.

    Posted : 25/03/2019 4:48 pm
    zubonzo
    (@zubonzo)
    Active Member
    RE: Mk3s filament sensor not working

    @keegan-m

    It seems to me that the plastic piece that slides between the sensor on the chip when a filament is inserted is slightly too large.

    I just had the same problem with the sensor and checked all connections, etc. which were correct.

    The ball and magnet are working properly as well

    It seems that the plastic part that moves between the sensor when a filament is inserted is slightly too large. If I replace the chip slightly off to the left (looking down when standing in front of the LCD display) from being seated correctly it will give the correct IR reading.

    I believe it's a mechanical problem, not an electrical one.

    Posted : 29/04/2020 9:00 pm
    George
    (@george-8)
    Eminent Member
    RE: Mk3s filament sensor not working

    I had the same problem,

    Check this/these out:

    https://help.prusa3d.com/en/article/ir-filament-sensor-troubleshooting-mk2-5s-mk3s_112226/

    this one worked for me

    https://www.prusaprinters.org/prints/8624-mk3s-ir-sensor-spacer-05-mm/files

     

     

    MK3 updated to MK3S / mainly textured steel sheet (also have a smooth one) / PLA and PETG

    Posted : 23/09/2020 10:20 am
    George
    (@george-8)
    Eminent Member
    RE: Mk3s filament sensor not working

    and just to stress this out. 

    This is a design flaw!

    At least on the upgrade instructions (form MK3 to MK3S) prusa could ask you to check for this before everything was assembled and include some spacers / shims....

    MK3 updated to MK3S / mainly textured steel sheet (also have a smooth one) / PLA and PETG

    Posted : 23/09/2020 10:22 am
    mafredri
    (@mafredri)
    Active Member
    RE: Mk3s filament sensor not working

    @jorgemarmo

    I must agree with you that this is a design flaw. Possibly the tolerances are simply too close and easily prevents the FS sensor from working correctly. When I first assembled my printer, it seemed to work. However, after my first filament change I noticed it no longer did. It always detected filament present. Intuitively I solved this by cutting a 0.2mm first layer test print and placing it as a shims under the sensor, this fixed it and it's been working ever since. So it was quite a small margin for me.

    But shims are a bit too hacky to me. When I disassemble my extruder at some point, I'm going to try out this mod: Prusa MK3S Filament Sensor Lever Upgrade - Thingiverse. It's a slightly resized FS lever printed at higher detail.

    This post was modified 4 years ago by mafredri
    Posted : 23/09/2020 9:30 pm
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