Filament Feeding Problems with MMU3
I've had my MMU3 (attached to MK4S) for about a year now. It has worked most of the time with little problems here and there. I am now in a situation where the problems are making me want to through it out the window.
The primary problem is the MMU grabbing the filament when it is fed in. I've cut the filament to a sharp point, but it often does not grab it and pull it in. I've checked the gears and they are clean so should grab it just fine. Sometimes, it grabs the filament, but only pulls it a few centimeters and then it stops advancing. I've kept the idler tension as described here: https://help.prusa3d.com/guide/6-pulley-body-assembly_328918#333348
A second problem (probably related) is that I often get an error at the end of a print where the filament gets stuck pulling out of the Nextruder. There is just a tiny bit of extra filament that makes it a hair more difficult to pull it out. I suspect that the MMU is not able to pull hard enough to extract the filament from the Nextruder, although it should.
Please help! I really don't want to have to face my Bambu family members with a machine that doesn't work as well as theirs.
RE: Filament Feeding Problems with MMU3
problem 1 feeding issues:
i've got a mk3s+ so i am not sure if it's actually different or not, but the expectation with the mmu is a square cut (point was without)
any case i had something similar start to happen and i discovered the pin holding the idler into the cover had actually started to walk it's way out (i pushed it back in and added a drop of super glue) . let me know if yours is trying to escape too.
problem 2 stuck in hot end:
ramming settings is what makes the shape of the filament before trying to pull it back. no 2 printers are the same sadly, BUT I CAN TRY, what type of filaments are you trying to use? i'll share what i use .
RE: Filament Feeding Problems with MMU3
1. I'm not sure what pin you are referring to. Is it the one pointed to by the red arrow in this image: https://help.prusa3d.com/guide/6-pulley-body-assembly_328918#331700 ?
2. I almost always print with PLA; occasionally with PETG.
RE: Filament Feeding Problems with MMU3
I think they mean this pin
Which should be secured with an M3X10 screw like this
Regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility.Location Halifax UK
RE: Filament Feeding Problems with MMU3
other side was the one sliding out on me, 1 and 2 printed without issues, 4 and 5 started having feeding issues.
prusa slicer, filament, ramming parameters, mine below
RE: Filament Feeding Problems with MMU3
Thank you! I'll check once it's done printing. I've got it going without the MMU at the moment.
RE:
I don't think it's the pin that has gotten loose. See attached photo
RE: Filament Feeding Problems with MMU3
Are the pulleys tight on the step motor drive shaft? Wild guess, I can only guess what the symptoms of a loose pulley would look like but it would seem difficult / impossible to tighten them reliably without threadlock.
RE: Filament Feeding Problems with MMU3
Great suggestion. I just checked and they all were tight.
RE: Filament Feeding Problems with MMU3
What I've been finding on mine is that the position of the gears is what matters the most. Whenever I have filament fail to load or be difficult to load like you described I open the unit and check gear position. Make a slight adjustment to perfect center and then boom, perfect function again.
RE: Filament Feeding Problems with MMU3
yup, on yours that side cant go anywhere. double check the other side, same screw/pin.
chance the gears are looks that interact with the rollers on the idler and filament? able to walk side to side?