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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)
Active 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)
Active 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)
Active 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)
Estimable 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?

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
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