Filament catch spot during loading
I had all kinds of issues once I had my mmu2 up and running. One that was causing almost constant fails is the festo on the top of the extruder assembly. Took me a while to figure out what was causing it ended up being the orange tube having it's taper on the inside of the tube allowed the end of the filament to catch on a small shelf inside the festo where the orange PTFE would sit on, if the tube were cut perfectly flat. Here's a very rough drawing of what was going on. I could push filament through just fine sometimes, but other times even a perfectly shaped end could catch, depending on the angle of the orange ptfe from where the head is at that time. I ended up cutting a small amount off the end of the orange ptfe tube and since doing it I've never had a single failure due to this. Something to check if it seems to grind your filament when loading.
Re: Filament catch spot during loading
Yeah, I noted this in the troubleshooting thread. Unfortunately it is not a total solution and there have been a few work-arounds for this.
My personal solution is to get rid of the festo and filament sensor and taking the Bowden into the extruder body, which I reprinted to lock the (slightly longer) Bowden in place, a few millimetres abode the Bondtech.
I also use a 2.5mm ID Bowden.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…