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MFM recurring error

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Filament Monitor
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  • undefined
    wouldstain
    last edited by 18 Feb 2022, 15:59

    @Phaedrux @dc42 @T3P3Tony

    I've been dealing with a long-term recurring issue with my MFM where I keep getting the following error:

    Filament error on extruder 0: tooLittleMovement

    There seems to be no rhyme or reason behind it. I've run off several of the same print, sometimes I get no errors, sometimes I get multiple errors such as below. At this point, I am able to resume from the Status page button with no other action.

    The only common thread with this issue is that it seems to happen with greater frequency when printing PLA. I am able to print a complete PLA job with the MFM disabled but that leaves me with no filament run-out protection.

    I dont want to toss the MFM out but I'm getting pretty frustrated by this problem.

    HW Info:
    Board: Duet 2 WiFi (2WiFi)
    Firmware: RepRapFirmware for Duet 2 WiFi/Ethernet 3.4.0beta7+7 (2022-01-14)
    Duet WiFi Server Version: 1.26

    MFM is V 1.7a

    Sample M591 d0 outputs:

    2/18/2022, 7:48:34 AM m591 d0
    Duet3D rotating magnet filament monitor v3 on pin e0stop, enabled, sensitivity 26.26mm/rev, allow 1% to 200%, check printing moves every 3.0mm, version 3, mag 131 agc 63, measured sensitivity 27.19mm/rev, min 1% max 108% over 207.6mm
    2/18/2022, 7:46:53 AM Resume state saved
    2/18/2022, 7:46:50 AM Error: Filament error on extruder 0: tooLittleMovement
    2/18/2022, 7:45:07 AM M24
    Printing resumed
    2/18/2022, 7:44:58 AM m591 d0
    Duet3D rotating magnet filament monitor v3 on pin e0stop, enabled, sensitivity 26.26mm/rev, allow 1% to 200%, check printing moves every 3.0mm, version 3, mag 131 agc 63, measured sensitivity 29.36mm/rev, min 0% max 116% over 59.0mm
    2/18/2022, 7:44:55 AM Resume state saved
    2/18/2022, 7:44:51 AM Error: Filament error on extruder 0: tooLittleMovement
    2/18/2022, 7:44:25 AM M24
    Printing resumed
    2/18/2022, 7:43:42 AM m591 d0
    Duet3D rotating magnet filament monitor v3 on pin e0stop, enabled, sensitivity 26.26mm/rev, allow 1% to 200%, check printing moves every 3.0mm, version 3, mag 130 agc 63, measured sensitivity 26.02mm/rev, min 0% max 104% over 600.0mm
    2/18/2022, 7:43:05 AM Resume state saved
    2/18/2022, 7:43:02 AM Error: Filament error on extruder 0: tooLittleMovement
    2/18/2022, 7:38:04 AM M24
    Printing resumed
    2/18/2022, 7:34:22 AM m591 d0
    Duet3D rotating magnet filament monitor v3 on pin e0stop, enabled, sensitivity 26.26mm/rev, allow 1% to 200%, check printing moves every 3.0mm, version 3, mag 132 agc 63, measured sensitivity 25.79mm/rev, min -1% max 103% over 2959.5mm

    20220218-075422_flatbook_pages_1_0.2mm_PLA_.gcode

    021822_config.g

    undefined undefined 2 Replies Last reply 18 Feb 2022, 16:54 Reply Quote 0
    • undefined
      alankilian @wouldstain
      last edited by 18 Feb 2022, 16:54

      @wouldstain said in MFM recurring error:

      agc 63

      Your AGC is on the low side of the range which MIGHT indicate the magnet is too close to the sensor IC and it may be rubbing on the top of the sensor.

      That would cause a "Too little movement" indication.

      I would take it apart and check.

      SeemeCNC Rostock Max V3 converted to V3.2 with a Duet2 Ethernet Firmware 3.2 and SE300

      undefined undefined 3 Replies Last reply 18 Feb 2022, 18:23 Reply Quote 0
      • undefined
        infiniteloop @wouldstain
        last edited by 18 Feb 2022, 16:59

        @wouldstain Electrically, your MFM looks fine. I can imagine a mechanical reason for the "drop-outs" you encounter: maybe the magnet does not always rotate? One possible reason is a "hanging" idler - tolerances of the design are a bit narrow for FFM printers. In my case, some filing on the two idler parts, especially to clear the path of the bearing, made the MFM go smooth.

        undefined 1 Reply Last reply 18 Feb 2022, 18:24 Reply Quote 0
        • undefined
          Surgikill @alankilian
          last edited by 18 Feb 2022, 18:23

          @alankilian Thanks for this. I've been having issues. My agc is 63 also. The center bearing was rubbing on the sensor. Hopefully it's not destroyed, there was a pretty nice ring rubbed into it.

          1 Reply Last reply Reply Quote 0
          • undefined
            wouldstain @infiniteloop
            last edited by 18 Feb 2022, 18:24

            @infiniteloop I actually marked the idler so I can see it moving. Also.. when I put it together I did some filing to makes sure stuff was moving freely. I can pull filament through it manually and it feels like it moves smoothly.

            undefined 1 Reply Last reply 18 Feb 2022, 20:59 Reply Quote 0
            • undefined
              wouldstain @alankilian
              last edited by 18 Feb 2022, 18:32

              @alankilian I had not looked at distance between sensor and magnet as a possibility. Any suggestions on what the distance should be?

              undefined 1 Reply Last reply 18 Feb 2022, 18:35 Reply Quote 0
              • undefined
                alankilian @wouldstain
                last edited by alankilian 18 Feb 2022, 18:35

                @wouldstain THIS page says the target distance is 0.25mm and that the AGC should be between 50 and 105 so your AGC is not out-of-range, just on the low-side of the range.

                Since you're getting excellent above-desired reading of 104% to 116% and you're getting 0% minimum it seemed to be that your magnet was getting stuck and not turning.

                So take a look and see if you see any marks on the top of the sensor and if so, add a sheet of paper or two to the case and see if your AGC gets larger and if it works better.

                (My AGC is 123 which is out-of-range high, but it seems to work so I'm not going to fiddle with it.)

                SeemeCNC Rostock Max V3 converted to V3.2 with a Duet2 Ethernet Firmware 3.2 and SE300

                undefined undefined 2 Replies Last reply 18 Feb 2022, 18:51 Reply Quote 0
                • undefined
                  wouldstain @alankilian
                  last edited by 18 Feb 2022, 18:51

                  @alankilian Thank you!
                  I'll definitely give that a try later!

                  1 Reply Last reply Reply Quote 0
                  • undefined
                    Surgikill @alankilian
                    last edited by 18 Feb 2022, 19:30

                    @alankilian Do you know of any reason the AGC would climb during a print? I took some plastic sheet and shimmed the monitor. My AGC started at 75, and I have been pulling the states throughout the print, and now it has climbed to 90. I also have had 2 false "Too little movement" on a 45 minute print so far, so it doesn't seem to have fixed anything.

                    undefined 1 Reply Last reply 18 Feb 2022, 19:40 Reply Quote 0
                    • undefined
                      alankilian @Surgikill
                      last edited by 18 Feb 2022, 19:40

                      @surgikill

                      Rats, it was worth a shot anyway.

                      The AGC would go up if the space between the magnet and sensor was increasing. Maybe your paper is springing-back somehow?

                      Anyway, I'm sorry it didn't help.

                      I think one of the duet gang can jump on and see if they have any further suggestions.

                      SeemeCNC Rostock Max V3 converted to V3.2 with a Duet2 Ethernet Firmware 3.2 and SE300

                      1 Reply Last reply Reply Quote 1
                      • undefined
                        infiniteloop @wouldstain
                        last edited by 18 Feb 2022, 20:59

                        @wouldstain Let's look further. In my setup, the filament can go into the MFM with an angle - if it was too much bent, I got false readings, especially with stiff filaments. If you can exclude mechanical problems, you might want to check print moves at a higher distance (currently, you stick with the recommended 3 mm). Try 5-10 mm instead.

                        Finally, there is a hot debate about the usefulness of adding a capacitor to the power lines of the MFM, you can look it up here. But I think this will only help in case of unstable supply voltage.

                        One last question: where do you locate your MFM, and how fix is the distance between it and the extruder?

                        undefined 1 Reply Last reply 23 Feb 2022, 01:39 Reply Quote 1
                        • undefined
                          wouldstain @alankilian
                          last edited by 19 Feb 2022, 00:18

                          @alankilian gapped with some paper as suggested.
                          Same issue:
                          m591 d0
                          Duet3D rotating magnet filament monitor v3 on pin e0stop, enabled, sensitivity 25.63mm/rev, allow 1% to 200%, check printing moves every 3.0mm, version 3, mag 131 agc 74, measured sensitivity 33.09mm/rev, min 1% max 132% over 61.4mm

                          undefined 1 Reply Last reply 19 Feb 2022, 00:32 Reply Quote 0
                          • undefined
                            alankilian @wouldstain
                            last edited by 19 Feb 2022, 00:32

                            @wouldstain

                            Bummer!!!

                            As an experiment and even though it's wasteful, maybe helpful.

                            Try:

                            • Raising the extruder temp a LOT. 15C or so.
                            • Moving the extruder 20mm away from the bed.
                            • Run your print.

                            You'll be making spaghetti, but this will demonstrate if the extruder is clogging or if there's some interaction between the extruder and the print that's jamming the filament.

                            If it "prints" without an under-length move we'll figure out more experiments.

                            SeemeCNC Rostock Max V3 converted to V3.2 with a Duet2 Ethernet Firmware 3.2 and SE300

                            undefined 1 Reply Last reply 19 Feb 2022, 16:21 Reply Quote 0
                            • undefined
                              Phaedrux Moderator
                              last edited by 19 Feb 2022, 04:48

                              Photos of your sensor setup and printer? Maybe we can spot something.

                              Z-Bot CoreXY Build | Thingiverse Profile

                              undefined 2 Replies Last reply 19 Feb 2022, 16:22 Reply Quote 0
                              • undefined
                                wouldstain @alankilian
                                last edited by 19 Feb 2022, 16:21

                                @alankilian I can tell you for certain the extruder is not clogging.
                                I've actually set up a macro to disable the MFM when printing PLA:

                                   M591 d0 s0
                                

                                This allows me to run entire PLA jobs without interruption but also without the protection of run-out detection. I was able to finish off the tail ends of two spools yesterday thanks to having the MFM enabled but there were several false-stops during the process.

                                1 Reply Last reply Reply Quote 0
                                • undefined
                                  wouldstain @Phaedrux
                                  last edited by 19 Feb 2022, 16:22

                                  @phaedrux As soon as the current job is complete I'll get some photos.
                                  Assuming you want to see it mounted as well as on the bench and disassembled.

                                  1 Reply Last reply Reply Quote 0
                                  • undefined
                                    wouldstain @Phaedrux
                                    last edited by 19 Feb 2022, 17:21

                                    @phaedrux

                                    Photos as requested.
                                    Please let me know if there's something else you'd like a pic of.

                                    IMG-4154.jpg IMG-4153.jpg IMG-4152.jpg IMG-4151.jpg IMG-4150.jpg IMG-4149.jpg IMG-4148.jpg

                                    1 Reply Last reply Reply Quote 0
                                    • undefined
                                      Phaedrux Moderator
                                      last edited by 19 Feb 2022, 21:39

                                      Have you tried re-printing the casing in higher quality?

                                      Z-Bot CoreXY Build | Thingiverse Profile

                                      undefined 2 Replies Last reply 20 Feb 2022, 02:34 Reply Quote 0
                                      • undefined
                                        wouldstain @Phaedrux
                                        last edited by 20 Feb 2022, 02:34

                                        @phaedrux I havent but I can although the casing is clean on the inside. I had some first layer issues IIRC and it still has some dry bedweld on it (got distracted and forgot to rinse).

                                        1 Reply Last reply Reply Quote 0
                                        • undefined
                                          wouldstain @infiniteloop
                                          last edited by 23 Feb 2022, 01:39

                                          @infiniteloop I have the MFM sitting directly atop the extruder and the PTFE tube comes in close to vertical so I'm not concerned about the angle of the filament path.

                                          I am considering picking up a piece of copper tube from McMaster and replacing the bit of PTFE tubing connecting the MFM to the extruder but I really dont think that's where the problem is.

                                          I'm inclined to print a new casing and giving that a try as I noticed that the ring on the MFM sensor from the magnet rubbing was a partial circle which would indicate to me that there's a slight tilt to the magnet.

                                          I think an injection molded case would remove any uncertainty around it but I'm not certain that would resolve this issue.

                                          undefined 1 Reply Last reply 23 Feb 2022, 09:43 Reply Quote 0
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