The Hook of Death!!!
Hello Prusa community. I have a very annoying issue that has plagued me for a while. I have a MK3S/MMU2S and when I manually unload the filament, do a 1st layer calibration, or stop a print, the filament always gets hooked as it's coming out of the extruder. Take a look at this image.
It makes a hook that grabs right above the gear.
It very tedious to resolve when it happens. I have to cut above the MMU2 grind, remove the extruder idler push filament back through so I can cut the hook off and pull the ~1m of filament from the PTFE tube. This happens every time I manually stop a print or do a 1st layer calibration. I do this multiple times a week. I have cut off hundreds of these hooks. It doesn't happen during filament swaps while printing.
This happens when I use the default configurations with any filament. I have replaced the entire extruder assembly and it still occurs. If anyone has any ideas, I would really appreciate the feedback.
You are not the first person to see this issue. Take a look here:
For the first post, you will get to enjoy quite a bit of philosophical discussion between me and @steve-e3 regarding the MMU itself, but there are a bunch of good ideas hiding in there.
I wanted to loop @steve-e3 back into this conversation because your picture is an excellent clue to what may be happening and is much better than I was able to capture.
I was having the exact same issue but have fixed it. I will update the post at the first link above with my experience shortly. Don't get your hopes up - I was not able to isolate the issue to a single root cause.