MMU2 keeps blinking  

Re: MMU2 keeps blinking

I would clear it (what ever it wants to satisfy the error.sometimes you need magic to figure out what it wants) then maybe adjusted tensions abit. as long as the filament loads and unloads easy. the only thing left is tensions on the 2 screws.

it's a shame there isn't a LED screen to display a real error code... o wait....

Re: MMU2 keeps blinking

i had something like this happen on my machine, the MMU2 basically could not recover. mine got confused where the blinking light was on #2 but the selector body was on #1, the left and right buttons had no effect other then to push the wrong filament out either a little (left button) or alot (right button) the center button had no effect at all. i tried to fix it and nothing would work except for ejecting the filament out the front either a little or a lot.
the print was toast at that point i had to do a power on/off/on.

i figured if i tried to manual index the selector left to #2 and then make it touch the FINDA on eject it would just make things even worse as the selector would be completely out of sync with Home. at that point it already was out of sync.

now part of my situation was that filament #2 had snapped at the spool and then the filament was sticking out the front. i suspect the selector then tried to move and jammed then it could not get into position and the computer was completely confused.

Re: MMU2 keeps blinking

In my case it's not a jam, I can manually push the filament all the way through the orange PTFE tube.

Re: MMU2 keeps blinking

I just contacted support. They believe the FINDA might be the cause. It could be too low, so some debris might be triggering the FINDA.
I will try to get it up one turn and see if it helps.

Re: MMU2 keeps blinking

What am I doing wrong? For 2 hours the MMU2 works like a charm, no hickups.
Then suddenly I get an unload error.

The selector is a F1, while the LED is blinking at F5. When pressing the middle button it tries to unload F1, but it's out allready.
Nothing is jamming the PTFE tube and nothing is left behind in the selector.

Once I managed to get it printing again, within 5 minutes the same thing happens again.
I don't understand:
1) what's exactly happening (conflicting selector position, blinking LED)
2) how I can solve the issue (i.e. continue printing, without the same error within 5 minutes).

This sounds to me like the FINDA is incorrectly registering filament present when there isn't any.

I suggesting sticking a bit of filament backwards into the MMU to try to dislodge any debris which might be stuck in there.

Re: MMU2 keeps blinking

Yesterday I did another test with the FINDA moved up slightly. Same problem!
But this time around, when removing the orange PTFE tube, I noticed very thin strings of filament left in de PFTE tube and selector.

Turns out the PLA was stringing quite a bit (and was still attached to the end of the filament).
How come 49/50 times the material changes just fine and the 50th time it strings and causes this problem.

But I guess I have to tweak the material settings some more!

Re: MMU2 keeps blinking

hey, make sure your filament isn't dragging anywhere. that can mess with ramming stuff. just a word of warning before messing with settings

Re: MMU2 keeps blinking

I am not using the standard Prusa filament holders, but the improved ones (with big white rollers). Almost no resistance at all.

Re: MMU2 keeps blinking

im talking about resistance going thru the MMU unit. if it wasn't for my trusty tiny files, I would be having issues.

and zero resistance for the spools is a bad idea.... I went crazy with it..one tiny tug and the spools would start spinning. what a mess. the "fast load" really can get the spool spinning.

Re: MMU2 keeps blinking

Ah you mean through the selector, I will check that.
About the spools, I said "almost no resitance", this is not the same as "zero resitance". It doesn't keep spinning when you pull, but it doesn't take the MMU unit very much force to pull, which is a plus.

Re: MMU2 keeps blinking

just giving ideas. I forget are you running stock pla?

Re: MMU2 keeps blinking

and, is it during loads or unloads yours jams more? sometimes its hard to tell, when it's happy dance kicks in

Re: MMU2 keeps blinking

I am using a basic PLA and BVOH. I use the standard PLA preset.
The stringing/jams occur on the PLA filament during unload.
But not all the time, just once in a while, but this makes it impossible to print anything for over 2 hours.

Re: MMU2 keeps blinking

What is the best way to test your load/unload settings for a specific filament without having to print for hours?

Re: MMU2 keeps blinking

print a single layer something

maybe the "load to hotend"

Re: MMU2 keeps blinking

when mine went nuts, the Finda was clear on mine. after machine power off/on the selector reset and i re-setup the same print again and 13 hours later it finished this time with out a problem.

i suspect in my case when the #3 filament snapped it stuck out the front then the selector wanted to do a spool change hit #3 filament that was sticking out and attempted to re-home. homed in error then could not load filament 1 and became hopelessly out of sync.

maybe if the firmware supported a manual re-homing with the buttons then you could recover from this.

Re: MMU2 keeps blinking

I managed to complete a 16 hour print with 3 colors PLA (a layer shift nearly at the end still ruined the print, I should have enables crash detection), but a 16 hour MMU print without loading/unloading ussues is a record for me!

It gave me enough courage to start a 36 hour print, 1 color PLA and soluble interfaces with BVOH. Today I tried twice, but both attempts failed again at around 10-15 mm height. Both times it looked like a filament unloading problem, but once restarted, both times the layer wouldn't stick. So I think it air printed one or two layers.

I am kinda out of ideas 🙁

Re: MMU2 keeps blinking

After tweaking the cooling and ramming settings I managed to do the 40 hour print without major issues.
Two halts because of a loading issues, that resumed just fine. The result is awesome.

Retried the 16 hour print again, again without issues.

So for everyone having problems, the main issue is your filament settings!

Re: MMU2 keeps blinking

nice, Im still at stock settings 😀

thing is working like a champ. odd load/unload issue around once a day maybe.