Keep getting a filament stuck message on my MK4S  

RE: Keep getting a filament stuck message on my MK4S

I'll double this. I was having the same stuck error every time I'd go to start a print. Backing the idler screws off by 3 turns has made the error go away; 2 turns was not enough, it specifically took 3.

Posted by: @james-36

Solved for me!  I just had this same problem on a 3 to 4S upgrade.  The build went fine and all the tests passed.  First print - filament stuck error the instant gets to point starts the print.  Again and again - cannot print any of first layer.  I tried someones comment about increase idler tension also failed.

Whats solved for me was to reduce the tension on the filament idler lock.  The build instructions say set the long screws equal with the face of the swivel part.  I moved about 3 turns loser and then see no error.  Somebodies comment about the stepper motor made me think of this: too much tension on the filament idler and that could create enough drag to appear same as if filament was stuck.  

RE:

• New here and looked for this exact thread. I have completely given up on the stuck filament sensor. Never once has the filament been stuck, it just wigs out and I have to reprint the piece. Latest was a 1cm wide completely flat piece, halfway through the print it decided the filament was stuck. Unload reload purge dance and again filament stuck after 0.1 seconds so I can’t even pause the print after reloading. As far as I can tell it serves absolutely no purpose other than ruining upwards of a hundred prints. I will never turn that sensor on again.

RE: Keep getting a filament stuck message on my MK4S

I just upgraded my MK4 to MK4S. After the upgrade, 100% of my first 12 or so prints paused with the "Stuck Filament Detected #26101" error...

At the start of the print, the filament perfectly extruded for the 100mm or so purge strip. The printer then reported a stuck filament, parked to the right, demanded a reload, restarted the print, which completed every single time. In other words, I had only one error per print, at the very beginning.

My fix might not be the best but I decided to change the 0.4 nozzle. (I use the 0.4mm, not the 0.4mm high flow because I have the MMU3, and Prusa recommends the regular 0.4mm even on the MK4S in this case.) My nozzle came with the MK4. It was "old" but by no mean at the end of its life in my opinion. 

After changing the nozzle, everything went back to normal. I just performed 4 prints with numerous filament and color changes, in PLA and in PETG.

RE: Keep getting a filament stuck message on my MK4S

For me, the issue was solved when I stopped using PLA settings for PETG filament. I guess the lesson for me was - read labels when you buy stuff.

RE: Keep getting a filament stuck message on my MK4S

just a FYI, I took this entire thread and submitted to the product team for review. 

RE: Keep getting a filament stuck message on my MK4S

Thank you, ironically, the issue has come back, thought I had it resolved. I start a print, the prime line goes down and I instantly get a filament stuck. Once I eject and insert the filament it prints fine, unless it’s a large gridfinity box, still won’t do those!

RE:

Posted by: @same-old-shane

just a FYI, I took this entire thread and submitted to the product team for review. 

Thank you, Shane!  It’s about time!

Here’s another one I hope you can help with… https://forum.prusa3d.com/forum/english-forum-original-prusa-i3-mk4s-hardware-firmware-and-software-help/mk4s-mmu3-6-40-alpha-fw-stuck-at-reloading-filament-99-parking/#post-765321

RE:

Hi Shane 

It' s while I heard of you. 

For the guys with the issue. Mk4 is using the loadcell in several functions. 

During the MBL is punching with the nozzle to the bed to check the plate. Seems that during the printing it measures the tension at the nozzle entrance not from the plate side, but from the extruder gear side (opposite tension sign). Some knowledge where the loadcell is mounted can help the imagination.  My guess is, when the resistance i to high ( the filament enters the nozzle too hard) this can be the caused by the temperature which is not high enough to mold the filament inside of the nozzle. Do not forget to have the loadcell calibrated.  Do not take too seriously the nozzle temperature you see on the display, it can vary in unexpected range. Even the symptom showed on one of the pictures looks like low nozzle temperature. Try increase the nozzle temperature by even 10° C. You could probably avoid the error message and even get better first layer print.

Let me know if it helped.

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One more thing. I am using an mk3s upgraded to mk4, not mk4s.  When you upgraded the mk4 to mk4s you had to reassemble the nozzle. Keep in mind the printer is measuring the heatblock temperarure and not the nozzle temperature directly. So any temperature resistance ( created during the upgrade) between the nozzle and the heatblock can add difference between the measured and the real nozzle temperature. E.g printing PETG with mk4 I stopped using the print temperature of 230°C. The best temp for me is 250°C. Especially when you use the linear advance feature for fast printing.

During the faster speed the time the filament spends inside the nozzle is shorter so it needs a higher temperature to receive the heat energy to mold to satisfactory consistence.

RE: Keep getting a filament stuck message on my MK4S

It's particularly telling, at least for me and others having arrived at the same solution, that solely reducing the tension on the filament idler lock caused our stuck filament errors to go away.

Not saying other people aren't having temp issues, etc, but having not changed any of my print settings, temps, etc, and no longer having issues after the aforementioned fix seems to suggest a specific issue with the upgrade process and/or our hardware.

RE: Keep getting a filament stuck message on my MK4S

This is my solely opinion, as I did not study this part of FW in detail. The right answer should come from the function designers and/or programmers. Shane forwarded this issue to programmers. Let us see what answer will arrive.