lynn.u
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Please help me with my MMU2

Jan 10, 2019 2:29 am

So, first post...

I've had my MMU2 for a few months now and have exactly 2 successful prints. I've done every single thing I can think of and I still can't get it to work. Can anybody please help me?

Here's what I've done:

replaced all ptfe tubes with 2.5/4 ptfe
flashed to latest firmware for both the mk3 and the mmu2
Modified the Festo on the hot-end to the pass-through variety. (from thread in this forum)
downgraded the firmware on the mmu2 because of a post I saw here.
modified all of the spool holders to this design (https://www.thingiverse.com/thing:3113520)
replaced the hot-end in it's entirety
Done the length calibration for all 5 spools about a billion times.
tried every slic3r setting I can think of

My tips look fine (maybe just a bit fat, but I can't seem to find a setting to thin them out)
I'm getting very little to no stringing.

My problem is that the filament seems to get jammed on load somewhere in the hot-end anytime after the first unload cycle of any color. I can hear it start to click and then eventually a flat spot gets ground in the filament.

I'm use 3d Solutech PLA and my settings are

Loading Speed at the start: 19
Loading Speed: 22
Unloading speed at the start: 140
Unloading speed: 90
Filament load time: 12
Filament unload time: 11
Delay after unloading: 0
Number of cooling moves: 3
Speed of the first cooling move: 20
Speed of the last cooling move: 20
Minimal purge on wipe towers: 15


Ramming Settings:

Total Ramming Time: 2.50
Ramming Line Width: 120
Ramming Line Spacing: 110

Extra Loading Distance: -6

I've tried to print the included mmu2 prints as they were, and then have tried multiple simple and hard models I've slice myself, all with 0 success.

Please is there anybody out there willing to help me out? I'm at my wits end.

-Lynn

P.S. Sorry if in wrong spot, first post and all...

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toaf
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Re: Please help me with my MMU2

Jan 10, 2019 3:51 am

so the filament is getting ground at the extruder gears? not the mmu gears?
I have a Prusa,
therefore I research.

thanks,
chris

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nikolai.r
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Re: Please help me with my MMU2

Jan 10, 2019 4:20 am

lynn.u wrote:
Jan 10, 2019 2:29 am
Please is there anybody out there willing to help me out? I'm at my wits end.
Hello Lynn and welcome to this forum. First of all please make a picture of the tip you're getting after first unload. It's easier for us to see where it might jam.

I would suggest following approach:
First you need to identify where exactly it's getting stuck. I'm always using the very powerful "Pause" function of the printer. So once the printer loaded the filament and you hear that jamming sound and you can see something is wrong, press select the Pause print function. Once the printer has parked the head. Select the nozzle temperature manually to the destination temp. Release the bondtech gear screws and open the window.
Now you should be able to see where the filament got stuck. You can also move it up and down, extrude some filament by pushing the filament with your hand down.

Again, it's very important that you can see and understand where exactly the filament gets stuck. It doesn't make sense to change elements of the printer without knowing the root cause.

Let us know the results and we can go from there.

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toaf
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Location: st. paul minnesota
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Re: Please help me with my MMU2

Jan 10, 2019 4:25 am

you can always preheat, then load to nozzle also. that might help for troubleshooting
I have a Prusa,
therefore I research.

thanks,
chris

dryja123
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Re: Please help me with my MMU2

Jan 10, 2019 1:23 pm

Prusa support via live chat is helpful too. They're slow but they'll provide you some good troubleshooting tips.

michael.c31
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Re: Please help me with my MMU2

Jan 10, 2019 11:41 pm

i am going to high jack this post as i think i am in the same boat. in my test print the green was not in use yet. i also attached my slic3r settings. i am wondering about going back a a 2.0mm hot end tube.
image001.png
image001.png (1.01 MiB) Viewed 234 times
Inland-PLA.zip
(3.6 KiB) Not downloaded yet
as a note if i try to just to PETG with no tool changes i get the same skipping behavior. if i bypass the MMU things seem fine.

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nikolai.r
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Re: Please help me with my MMU2

Jan 11, 2019 12:06 am

michael.c31 wrote:
Jan 10, 2019 11:41 pm
i am going to high jack this post as i think i am in the same boat. in my test print the green was not in use yet. i also attached my slic3r settings. i am wondering about going back a a 2.0mm hot end tube.
Is it PLA or PETG?

michael.c31
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Re: Please help me with my MMU2

Jan 11, 2019 12:58 am

the filament i am using is inland PLA. and the tips measure as follows.
green = 1.91mm
white = 2..04mm
light blue = 2.03
dark blue = 1.94mm (this one hasn't had many issue if any)

i guess what i don't get about the new PTFE tube i thought it was supposed to stop filament from getting bigger than the tube.

edit: which is why i mentioned the PETG it does seem to pick up flakes of PLA (i need to clean my gears) but on a single color print it will start off strong then seems to clog

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nikolai.r
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Re: Please help me with my MMU2

Jan 11, 2019 1:12 am

michael.c31 wrote:
Jan 11, 2019 12:58 am
the filament i am using is inland PLA. and the tips measure as follows.
green = 1.91mm
white = 2..04mm
light blue = 2.03
dark blue = 1.94mm (this one hasn't had many issue if any)

i guess what i don't get about the new PTFE tube i thought it was supposed to stop filament from getting bigger than the tube.

edit: which is why i mentioned the PETG it does seem to pick up flakes of PLA (i need to clean my gears) but on a single color print it will start off strong then seems to clog
The green one look pretty bad for PLA. Try with lower temp otherwise it will cause many issues.
My PETG looks like your green PLA.

michael.c31
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Re: Please help me with my MMU2

Jan 11, 2019 1:21 am

The green one look pretty bad for PLA. Try with lower temp otherwise it will cause many issues.
My PETG looks like your green PLA.
the green was not in use it was the white filament. and i have lowered the temp and that does help with stringing but the grinding that happens (as shown in my last photo) does not stop. a higher temp seems to lessen the grinding.

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