At my wits' end - filament jams every time
I built my MMU2, installed it, and after some monkeying around I was able to print a few 2-color Benchys with only a couple of layers missing. And I was pretty proud of my accomplishment. But after that, I haven't been able to get anything to print.
It seems that no matter what i do, the filament mushrooms and jams inside the PTFE tube above the extruder's bondtech gears. Every single time. I've tried other filament brands (currently trying with Inland, and the settings published elsewhere in the forum). I've tried longer ramming times, shorter ramming times, more cooling moves, less cooling moves. Different shapes to the ramming curve.
I reseated the PTFE tube at the top of the extruder. I realigned the Bondtech Gears. I removed the hot end to reseat that PTFE tube as well. I've adjusted the tension of the extruder and the MMU. I've tried different temperatures. Nothing seems to help.
I've read the guides and I've done the troubleshooting, as far as I can tell. I've been at it for over a month. Please, HELP!!!
Re: At my wits' end - filament jams every time
is your MMU a 2.5 or a 3.0?
if 2.5 it has been found out there is a different in the heat break and it needs to be replaced with a 3.0 version. prusa has apparently not tested the 2.5 version properly.
have you modified or changed anything in the extruder, are you using an aftermarket nozzle, like a ruby?
if you have then you need to change back to the prusa original nozzle as the shape inside these after market nozzles is flat inside at the base where the prusa is tapered and so you will always get a ballooned out filamanet at the tip which can jam backing out of the PTFE tubes.
“One does not simply use a picture as signature on Prusa forumsâ€
Re: At my wits' end - filament jams every time
It's an MK3 with an MMU 2.0. Thanks for pointing out the issue with the tip - I *AM* using a third-party (brass) nozzle at the moment. I will reinstall a Prusa one and try again.
Re: At my wits' end - filament jams every time
make sure the filament moves freely both directions.
I use allot of inland pla and I just use default prusa pla settings.
I have a Prusa,therefore I research.
Re: At my wits' end - filament jams every time
Nope. Unfortunately the Prusa nozzle hasn't helped at all.
I reduced the ramming time and volume to see if it helped. It doesn't.
This is fairly representative of the issue (this is the extruder end of the bowden tube)
Re: At my wits' end - filament jams every time
Nope. Unfortunately the Prusa nozzle hasn't helped at all.
I reduced the ramming time and volume to see if it helped. It doesn't.
This is fairly representative of the issue (this is the extruder end of the bowden tube)
I had that happen to me a whole bunch of times when my MMU was brand new.
Then it stopped happening.
I never figured out why. But my guess is that over time that little bit of PTFE tube got stretched out a little from repeated use, and it's now big enough that the filament can always pass easily and also it's big enough that it won't easily slip out of place.
I think a root cause could be that your tips are a little too fat. One thing you can try is reducing the number of cooling moves so that the tip is a little softer going into the Bondtech gears, which may help smoosh them down.
Re: At my wits' end - filament jams every time
@jorge.h2 How goes the battle?