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I'm Considering getting an MMU2 but...  

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IanG
 IanG
(@iang)
Active Member
MMU2 a Failure

 

Posted by: @pacobelan

Hello everyone. I recently got an I3MK3S kit and now after getting it built and making a few prints that all turned out great (thank you to everyone here who helped me get there) I'm considering getting the MMU2. Then I came here and saw a "Hot" post from someone who has had nothing but problems with the MMU2 and the post had quite a few replies from people who either are in the same boat or were before what sounded like a lot of troubleshooting, were able to get things working pretty well. I was going to just post this as a reply to that post, but I was concerned that because of the nature of that post that it might have attracted an inflated number of users with negative feelings about the unit and I'm hoping that more people have had a positive experience with it than a negative one.

So, knowing what you do about the MMU2, would you recommend it to someone thinking of getting one?

Thank you for any and all information!!! Have a great weekend (or week if you're late to this party).

 

Posted : 05/10/2021 8:10 am
IanG
 IanG
(@iang)
Active Member
failed mmu2s

I wouldn't recommend the MMU2 or any variations.

I had mine working very well for a weeks worth of prints large and small simple and technical. Then it presented a new problem

a problem I cant even find anywhere on the web. Every time mine wants to do a tool change it reboots or it selects a filament and half way through loading the carriage moves and selects another. Total jam! I'm over it. Painting the model would be quicker without failures.

Posted : 05/10/2021 8:16 am
Roy
 Roy
(@roy-3)
Eminent Member
Board problems
Posted by: @iang

I wouldn't recommend the MMU2 or any variations.

I had mine working very well for a weeks worth of prints large and small simple and technical. Then it presented a new problem

a problem I cant even find anywhere on the web. Every time mine wants to do a tool change it reboots or it selects a filament and half way through loading the carriage moves and selects another. Total jam! I'm over it. Painting the model would be quicker without failures.

Sounds to me like you have a problem with the controller board. Did you try re-flashing it with firmware? Otherwise I'd contact Prusa support about replacing the board.

Posted : 07/10/2021 10:14 am
tsamisa@cytanet.com.cy
(@tsamisacytanet-com-cy)
Trusted Member
Bought it made it "workable" after a while wouldn't buy it if i knew

This is my personal opinion based solely on my experience. I bought mmu2s just after purchasing the i3mk3 (which is a hell of a printer). The first 5-6 months i was giving up out of frustration but after calming down trying again to make the god damn thing to work. Now it works fairly well but i dont consider in par with the mk3 in terms of quality. The things that made it work. First 90% of failures where due to filament tips. I live in a hot climate and i bought mmu2s during summer and 40 degress C and the filament tips where always nasty. What helped was the magnet mod the rest of the people here recommends, antimix’s dribbling version of prusa slicer (it enables to drop the temp before changes thus not having to find the golden ratio between printing temp and retracting one, also it moves the tip a bit inside the hotend before extracting so as to create a “better” tip) and their blade firmware upgrade.

I use it now and then but I’m not sure if I would give my money again to buy it if I knew the hassle. There is a difference between a product that needs a bit of assembly and tinkering to work with one that takes that long and with a lot of frustration. I know that there are a lot of people for who the thing worked almost out of the box but there shouldn't be so many complaining about it. A product in my humble opinion that has so many disatisfied buyers is considered still in beta version. I hope that with their new XL printer to change the approach to a multihead. I wanted it for soluble materials and two heads or even a multitool with 2-4 heads option sounds a better approach.

Posted : 08/10/2021 6:21 am
IanG
 IanG
(@iang)
Active Member
mmu2s

I have the MK3s which is a brilliant printer. The MMU2s attachment is far from perfect. My recommendation  for Prusa is test any new gear using other filament not their own. I think a lot of the MMU2's problems lie right there. the Tolerances are different than Prusa and the plastic characteristics are probably different too. Its been suggested that I change out my control board, I believe number 2 board is in it now, am I prepared to shelve out more dollars is the question. I read that the stepper motor was underpowered and a solution to fix it, I tried that and it worked for a little while. Id have to say it has been problematic from day one but I didn't want to give up on it. I believe all the mods folk come up with is to work for their  filament which is fine,  but you shouldn't have to. When I got mine to work it was printing 5 colours for 21 hours with out a hitch for a month! I was loving it, then it went belly up again with a new problem. I searched the internet for the problem to no avail, until someone recently suggested the control board could be faulty. It could be the straw that brakes the camels back.

Posted : 08/10/2021 7:33 am
Rick Houlihan
(@rick-houlihan)
Eminent Member
Use Prusament if you want fewer problems with the MMU2S

I agree with this. I have minimal issues when I use Prusament filaments, when I use other manufacturers I see a lot more loading/unloading failure. I have not seen anything like some of the issues reported...everything I run into usually requires a little bit of operator intervention to clear.

I think users need to understand that the MMU and the MK3 each maintain their own state and the only data that is passed between them is MMU status which the MK3 will poll for and the filament load state of the extruder which is sent to the MMU so it knows to stop feeding filament and disengage the idler so the extruder can pull the filament freely. If the MMU has a load/unload error then all you need to do is make sure the filament is cleared and loaded properly which is a well documented procedure. I have seen the MMU get into a state that appears to be unclearable even when all filaments are loaded properly, but resetting the MMU will clear that state and at that point pressing the button on the MK3 will resume the print.

Overall I am happy so far with the purchase and I would buy it again.

Posted by: @iang

I have the MK3s which is a brilliant printer. The MMU2s attachment is far from perfect. My recommendation  for Prusa is test any new gear using other filament not their own. I think a lot of the MMU2's problems lie right there. the Tolerances are different than Prusa and the plastic characteristics are probably different too. Its been suggested that I change out my control board, I believe number 2 board is in it now, am I prepared to shelve out more dollars is the question. I read that the stepper motor was underpowered and a solution to fix it, I tried that and it worked for a little while. Id have to say it has been problematic from day one but I didn't want to give up on it. I believe all the mods folk come up with is to work for their  filament which is fine,  but you shouldn't have to. When I got mine to work it was printing 5 colours for 21 hours with out a hitch for a month! I was loving it, then it went belly up again with a new problem. I searched the internet for the problem to no avail, until someone recently suggested the control board could be faulty. It could be the straw that brakes the camels back.

 

Posted : 08/10/2021 4:24 pm
Christopher
(@christopher-4)
New Member
I would get one!

I've had my MMU2s since about 02/2021..At first it was a pain in my ass. I have a stock MMu2s and mk3s+ with the RMU filament buffer. The RMU is the key... I just finished the Tigger print (4x) 35 hours and 804 color changes. I had to help it a single time. The cause was the extruder having a bit of strings in it. 

The MMU needs time and patients along with understand how it works and what it needs to do. Once you got all that it works flawlessly 99% of the time.

Posted : 14/10/2021 1:46 pm
Rick Houlihan
(@rick-houlihan)
Eminent Member
RE: I would get one!

This is exactly the case.  Take time and assemble the unit very carefully, follow all of the instructions meticulously, watch the video linked above to learn how the unit works, and use high quality filament.  Do these things and the MMU works almost flawlessly. I have been running for a month now and I had the unit installed and operating after juts a few hours of tinkering.  My first few prints failed because I did not understand how the unit operated.  Once I got the hang of loading/unloading filament and clearing errors it has been running very very smooth with an occasional hiccup every now and then that is easily cleared. I do not use any modified parts at all and it seems to operate just fine with the stock configuration.

Posted by: @christopher-4

I've had my MMU2s since about 02/2021..At first it was a pain in my ass. I have a stock MMu2s and mk3s+ with the RMU filament buffer. The RMU is the key... I just finished the Tigger print (4x) 35 hours and 804 color changes. I had to help it a single time. The cause was the extruder having a bit of strings in it. 

The MMU needs time and patients along with understand how it works and what it needs to do. Once you got all that it works flawlessly 99% of the time.

 

Posted : 15/10/2021 8:59 pm
JMH714
(@jmh714)
Estimable Member

 

Posted by: @rick-houlihan

The chimney is such a simple mechanism...when the filament moves between the gears in the extruder it forces the outer panel to hinge outwards which forces the top to tip in and trigger the IR sensor.  What was the problem you were having with it?

I know it's a simple mechanism. The chimney kept move that caused sensor not being able to see a tripper. No matter how I move the chimney where the tripper detects and it would move out of way when I attempt to print. I've been to customer service, I've been to a 3D printer shop, I've been looking at dozens of videos about getting MMU2 to work, etc.... It's too much time consuming for me to try fix my issue and I just gave it up. 

I saw someone design an adjustable chimney that I haven't tried it yet - https://www.prusaprinters.org/prints/72366-mmu2s-extruder-filament-sensor-micro-adjuster . But I don't have time since I need to print out the whole MMU2 housing again because I threw them away (lol) - through I still have all parts (except printed parts).

 

Posted : 15/10/2021 9:35 pm
sylviatrilling
(@sylviatrilling)
Honorable Member
RE: Soluble supports

I'm thinking about getting the MMU2 strictly for doing soluble supports. I'm looking at printing in pla and bvoh. I print in white and paint with an airbrush, so multiple colors is of no interest but cleaner supported surface would be worth some effort to get it working. Is anyone here using soluble supports and satisfied with the results?

Mk3S+,SL1S

Posted : 15/10/2021 9:38 pm
ssill2
(@ssill2)
Noble Member
solubles

Yes it works.  as with anything with the MMU, it takes a little patience.  I've used only the recommended solubles, Verbatim BVOH and the PrimaSelect PVA+.  I did try a spool of Aquasys120 but had ZERO success with that.

I've used BVOH with both PLA and PETG and it seems to work fine.

Posted by: @sylviatrilling

I'm thinking about getting the MMU2 strictly for doing soluble supports. I'm looking at printing in pla and bvoh. I print in white and paint with an airbrush, so multiple colors is of no interest but cleaner supported surface would be worth some effort to get it working. Is anyone here using soluble supports and satisfied with the results?

 

Posted : 15/10/2021 10:00 pm
JMH714
(@jmh714)
Estimable Member

Yeah, it was my main reason I bought MMU2 for soluble. Colors came second for certain projects such as lettering on print.

Posted : 15/10/2021 10:12 pm
Thejiral
(@thejiral)
Reputable Member
RE: I'm Considering getting an MMU2 but...

I have printed easily more than 1000 hours with the MMU now (much of it with an officially not supported 0.25 mm nozzle and 0.1 mm layer height). I have managed prints with soluble support.

It wasn't a clean start for me. I belong to those people who had to invest some time (but not really any extra money) to get it work and work reliably. But in the end, I got where I wanted it to be. 

I know of others where it actually worked more or less right away with reasonable reliability and then here on the forum are a number of people who never made it that far for a multitude of reasons. Personally I would buy the MMU again and I think if you are aware that it might require some trouble shooting to get it dialed in properly it also delivers. You also need to be aware that you'll be wasting a lot of filament when printing tall with many colours and that printing multicolour takes much longer than single material. The results however can be absolutely fantastic. I would only advise against the MMU if you are intending to use it in a commercial rather than a private setting.

Mk3s MMU2s, Voron 0.1

Posted : 01/12/2021 11:14 am
Thejiral
(@thejiral)
Reputable Member
RE: I'm Considering getting an MMU2 but...

It does work with soluble support but it can be extra challenging. Definitely get it to work reliably with just different PLA (preferably Prusament) filaments first and then get into solubles, once that is working fine. Otherwise you might pile up issues on top of each other and trouble shooting gets unnecessarily complicated. If printing with soluble support is your key purpose and you are not really that interested in multi-colour prints, you might consider buying a dual extruder instead. Those can be more reliable, faster and especially considerably less wasteful. 

Mk3s MMU2s, Voron 0.1

Posted : 01/12/2021 11:21 am
HappyKatz
(@happykatz)
Active Member
RE: I'm Considering getting an MMU2 but...

My experience tallies with that of @baklin. The MMU2+ is a wonderful device once you get it tuned, and I am very happy that I purchased it, but it took some work to get it there.

I would double click on the advice about ensuring that your IR sensor is adjusted correctly (HINT: The idler screws will need to be tighter than you think and the screws holding the chimney can work loose after repeated use). In addition to the recommendations in the build guide, I would suggest running a print, and then watching the Support -> Sensor screen to ensure that you are getting a consistent '1' when the filament is engaged.

When I originally assembled the MMU2, I was able to get it running pretty quickly and (reasonably) reliably. However, when I moved my printer, I began experiencing unreliability with load / unload, and what looked like coms errors between the MMU2 unit and the printer. 

That persisted even after I flashed the firmware for both units. After finding this post ( https://forum.prusa3d.com/forum/original-prusa-i3-mmu2s-mmu2-hardware-firmware-and-software-help/i-found-serious-design-error-in-mmu2-electronics-hardware/), I tried running the MMU2+ with USB power attached. That seemed to address the COM issue, and make for more reliable loading / unloading. My guess here is that the new location had less steady / reliable power, and that the additional power addressed that issue.

I was still having issues with the Fil Sensor bit not holding steady for one particular shiny filament, but after adjusting the lighting around the IR sensor I have not had a repeat of that problem ( https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/filament-sensor-lever-matte-finish/#post-567769). Since then, I have been able to run the unit successfully with multi-hour prints and no load faults.

I point these out only because my issues seemed to come from the outer reaches of the twilight zone, but with the help of the forum, and Prusa support, they were addressable, and I can now print in living color! The result was well worth the effort, and I would definitely recommend the unit.

 

Posted : 23/01/2022 6:09 pm
seans4
(@seans4)
RE: I'm Considering getting an MMU2 but...

I've had mine for a couple of weeks now and have done many prints in 2 or 3 colours and had no problems at all ! Am i just very lucky??

I took my time setting it up as i built it and have had no problems, i even had no problems with the buffer, but i changed it to the RMU3 buffer as i liked the look of it and have had no problems with that either. Take your time building it and you will be fine.

Posted : 25/01/2022 5:23 pm
Christopher
(@christopher-4)
New Member
RE: I'm Considering getting an MMU2 but...

IMHO the rmu-mk3 is the key. After I got it, I have had next to 0 problems. Happy printing

Posted : 25/01/2022 5:31 pm
LMJ
 LMJ
(@lmj)
Eminent Member
RE:

If you want to spend a lot of time working on it then get one. I have had nothing but problems with it.  The Selector never knows where it is.

I purchased the MK3S and the MMU kit at the same time. Built the MK3S kit first to see what problems I may run into printing. Six months later I had the time to build the MMU kit while I wish I would of just built the MMU kit at the same time since you have to tear half the MK3S apart for the MMU. After all this the MMU is nothing but trouble. I still haven't got one color print to work. For all the money you would think it would be easier to use. I just seems the MMU board doesn't know where the selector is. If it takes you to long to fix the jam it goes nuts and should just power off and start over. I'm hoping the XL will work a lot better than this junk but not going to buy one until I know there are no problems with it.  We love our MK3S but the MMU is a lot of work and a pain in the ass it only good if you want to print in a different color from beginning to end. Good luck.

 

Posted : 26/01/2022 5:22 pm
Thejiral
(@thejiral)
Reputable Member
RE: I'm Considering getting an MMU2 but...

Sorry to hear but compared to a Mosaik the MMU is a lot cheaper. Be as it is, if you get an MMU you should at least consider the possibility of having to do some trouble shooting and dialing in. Yes, Prusa isn't frank about it but if you have ready this forum, it should be no surprise. I would recommend the MMU but only to those who are ok with that. Some don't even need to do much or even any trouble shooting at all and it works just fine but others do, me included. It is a complex piece of machinery and using it with all sorts of filament brands don't reduce the possibilities for issues either.

I also had issues with the selector initially. My main issue in the end was that the grub screw on the selector loosened and that way, the movement of the selector wheel got slowly out of sync with the movement of the stepper motor. Hence, after a number of changes that worked, hell broke loose and I got all sorts of errors and the selector was all confused. It can't hurt if you check if those screws are in place and tight.

Also check if the two filament sensors are working properly, these are common issues. You can do so in the Mk3s menu and just trigger both of them manually with some piece of filament and see if they are reliable and consistent. For better advice one one need to know in more detail what exactly is happening and what observations you can make before and at failure, is something blocking, at which point exactly does the selector move where it shouldn't, during loading, unloading, at another point?

Once you have dialed in your MMU it is actually a fairly reliable machine too but you have to be aware that it is more senstive to filament quality. If you get new filament brands one needs to take care they work well with the MMU or need to do some dialing in. However once you have some brands you know work fine it does work reproducibly fine.

Mk3s MMU2s, Voron 0.1

Posted : 27/01/2022 7:36 pm
IanG
 IanG
(@iang)
Active Member
RE: I'm Considering getting an MMU2 but...

My MMU2 s is currently sitting in the naughty corner gathering dust, its been there for some months now. Id get it running, it would go for a while then I'd get a barrage of errors. I do believe it relies heavily on Prusa filament. At 60 Australian dollar for one 1kg roll x 5 !Way way too expensive for me. This unit should have a had a disclaimer stating that it was only tested with Prusa filament. If I read that I would have declined. Paint is cheaper

Posted : 27/01/2022 9:15 pm
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