MMU3 Failure to Preload
Ok, so I purchased an MMU3 to go with my Core One. (I recall thinking I ordered the fully assembled version of the MMU3 with the enclosure kit, etc... but I got the unassembled version... and the website changed descriptions after I placed my order... and waited for months.)
Anyway, I've run into an issue with the MMU3 in that when I attempt to preload filament, it seems to miss the channel that takes the filament to the sector/finda assembly.
Prusa support told me that I did something wrong (possible, but hard to believe as I followed the instructions very carefully. (Might have missed something... but it did exactly what it said.)
I notice that the filament will run true IF I straighten it religiously prior to attempting to load.
Anyone have a clue as to what might be the issue?
RE:
...and the hideous noise it makes when attempting to load. No idea why. It worked fine on the left most position, and I even managed to print something, didn't like me anymore when I tried to preload station #2.
There should be a video... not sure why it's not showing up:
RE: MMU3 Failure to Preload
"Filament" - "Preload to MMU" - "Preload all" seems a pretty comprehensive dry-run. If this doesn't go smoothly, I wouldn't bother trying to print.
But, there shouldn't be any "ugly" mechanical noises (only on power-up while calibrating).
I ran through the process with five spools loaded, and the only noise is mechanical stepper whine and the clacking of the idler locking and unlocking. Anything else seems suspicious.
BTW, first thing I'd check is the pinions. Surely there is some way to permanently secure them without threadlock. But why anybody would try is beyond me 🙂
RE: MMU3 Failure to Preload
i guess my first question is: how sensitive to the filament being perfectly flat is the MMU3 during preload?
RE: MMU3 Failure to Preload
It needs a pointed tip, or at least a sharp angled cut.
I usually straighten them out quite carefully. A bend radius as unrolled from a spool will not work for first insertion (later during operation, of course).
RE: MMU3 Failure to Preload
Yeah, that’s what I’m concerned about… I’m not so sure I made any mistakes while building it. I was extremely careful and paid absolute attention to the instructions. I recall the MMU3 instructions being better than others.
I’m truly wondering if the actual problem is that the filament has to be more or less perfectly straight? (The Bambu printers don’t seem to have this issue; they pretty much just load anything.)
I’ll take out the two screws and verify that the idlers are still properly lined up and somehow didn’t get loose in the less than 10 minutes of operation.
RE: MMU3 Failure to Preload
Is the cutter blade assembled correctly? If not, it can get stuck.
RE: MMU3 Failure to Preload
I know your pain. I just went through the same issue after building mine. The filament does need to be near perfectly straight for a few inches and a pointy end helps a lot. Think about it. You’re trying to feed a 1.75mm dia. filament over a small gap and into a 2mm opening. Not much wriggle room there. Why on earth didn’t Prusa engineers provide a bigger target by making a funnel like receptacle?
As for the noise it sounds like you fed the filament passed the gears before the unit started turning and it is grinding against the body. Wait until the unit activates before slowly pushing in the filament. I had the same issue.
hope this helps. Happy printing.
RE: MMU3 Failure to Preload
Well, I did notice that the cutter was not turned on in the settings for the printer. I kind of assumed that would be an automatic kind of thing…
Otherwise, the MMU appears to be assembled properly.
if I straighten the filament and I mean really straighten it… It preloads without a problem. maybe my expectations are too high?
RE: MMU3 Failure to Preload
It's off for me too, no idea what the setting does. But check thr blade, it/'s a common mechanical assembly error. It will get stuck and cause noise.
With std filament the MMU runs like clockwork-needs to as there can be hundreds of changes per print.
RE: MMU3 Failure to Preload
As a general update, I was able to every single filament to preload.
I’m trying to figure out if it’s operator error… I think I might be assuming that this works more flawlessly ( or effortlessly, more to the point) than it does compared to my H2D.