Stuck Filament detection not working

[bryn51]

Printer model

Mk4

Firmware version

6.0.3

Upgrades and modifications

Prusa Original Enclosure

Printing from...

Prusa Connect

Describe the bug

During a print using Polymaker CoPA, a 0.25 mm nozzle, and the filament gets stuck in the hotend during the print. I grant that a 0.4 mm nozzle would have been better, but high accuracy and resolution were called for on the model.

I have also had this happen another way, when a knot occurred on the filament roll. In this versin, the type of filament does not matter, a knot can form of any filament when unlayered rolls are used.

Both times, I come back after some time and find that the printer is moving in mid air, not extruding, and positioned well above the last layer printed. The filament stuck in the nozzle condition was not detected, the print carried on, the printer unaware of this event, and the print was lost.

The stuck filament detection feature of the firmware is an existing feature, but not working as expected, therefore this is a Bug, not an enhancement or a feature request. It just needs to be made to work.

How to reproduce

Execute a simple print using Polymaker CoPA on a 0.25 mm nozzle, or another filament that will not tolerate a nozzle too small. It will jam sooner or later. Confirm if the stuck filament detection works as expected.

It is also possible to simulate this condition by stopping filament movement by locking the filament roll (simulating a knot).

Expected behavior

The stuck filament would be detected using the load cell sensor. If stuck filament occurs, the print should immediately stop, and:

• Maintain the bed temperature
• alert the user the fault has occured
• Offer the user the opportunity to clean the nozzle via "change filament" methodology
• on completion, resume the print.

Files

No response

[tlachmann]

Hello,

since a few days I,m struggeling with the same issue, in that case Esun PETG-HS Filament black.

Earlier (after first layer) or later (at approx 4mm height) the extruder stops moving the filament to the nozzle and no "filament stuck" notice is shown. (option is enabled)

After stopping the print, the filament will be always unloaded, so it does not jam in the extruder.

attached you can find pictures of the filament after unload. (It happens with less and more idler tension setting)

[bryn51]

the good news is that Prusa Support have divulged that this is being worked on. But no indication when the work will be completed as yet. Encouraging nonetheless.

[bryn51]

Hello,

since a few days I,m struggeling with the same issue, in that case Esun PETG-HS Filament black.

Earlier (after first layer) or later (at approx 4mm height) the extruder stops moving the filament to the nozzle and no "filament stuck" notice is shown. (option is enabled)

After stopping the print, the filament will be always unloaded, so it does not jam in the extruder.

attached you can find pictures of the filament after unload. (It happens with less and more idler tension setting)

I'd suggest you have the two issues:

• why is the filament jamming ? possible your nozzle temp is on the low side (that has happened to me)
• the firmware issue reported here.

[gwskala]

I'm not a programmer but thought I'd share my stuck filament error experience with my XL after installing the Prusa enclosure, upgrading some extruder parts and upgrading the XL firmware from V6.0.0 to V6.0.3. The issue I'm seeing is likely different than what is posted by Brin51 but it does involve the stuck filament diagnostic.

Here's a link to my post (and others with this problem): https://forum.prusa3d.com/forum/postid/716679/

My issue was resolved by re-flashing back to V6.0.1. I don't know what's changed but something is acting different in V6.0.3 (and some others suggest 6.0.2 may cause this problem)

[cazdghost]

Encountering this with 6.0.4 FW for MK4 with MMU3. rollled back to 6.0.1 as suggested and currently testing on a 23hr print. It is at 60% now and still dont have nay Stuck filament error.

[Rylan-Meilutis]

I had this issue and noticed that for me it only happened with certain brands of pla, my best guess is that the extruder area got hot enough that the pla softened and jammed, I ran the exact same gcode with a different pla and the print went without issue.

[Nitrowing]

My hours old MK4S is doing this. All up to date firmware. Prusament black PETG. Sick of this already and going back to my faultless 6yo Mk2S - if this issue isn't sorted by the weekend the printer is getting boxed and returned.

EDIT The MMU loads the filament and when it's printing is pulling the filament out of the nozzle - it's operating in reverse!