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MMU2 - will it ever work reliably ?  

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Flaviu
(@flaviu)
Estimable Member
Re: MMU2 - will it ever work reliably ?



Like I said already before, the issue seems to come from too much friction on the filament (from entering the MMU to the extruder)
I tested this by pushing and retracting the filament by hand.

The stock system should handle 2 mm in diameter easily. By drilling the festos to 2.5 mm and using 2.5 mm PTFE the whole system has much less friction which helped me a lot. Prusament should definitely work with stock settings or maybe a few more cooling moves.

Posted : 18/12/2018 10:44 am
dryja123
(@dryja123)
Honorable Member
Re: MMU2 - will it ever work reliably ?

I think the main point you can already see in this poll, the MMU2 can work reliable. We can print something which we couldn't before. It's definitely not easy to setup and not easy to maintain (like plug and print) but it is good enough to be sold. And it's definitely an improvement from MMU1.

I can definitely see your point in this poll; 52% of people who voted say that they're not able to get their MMU 2.0 to work. That's huge.

Posted : 18/12/2018 2:26 pm
Elvir liked
marc
 marc
(@marc-2)
Active Member
Topic starter answered:
Re: MMU2 - will it ever work reliably ?

Hi short update.
I changed my mindset regarding how to solve the issue.
My approach now is "you can't break what is already broken"!
So I did the following :
- replaced PRUSA Spool holders with a broom-stick
- cut the long PTFE tubes down to 2 cm
- used my DREMEL to drill out the remaining length of PTFE tubes to make sure all filaments will go thru (2mm)
- used my DREMEL to sharpen the tip of the PTFE tubes to make sure they fit snug into the MMU (I did not dis-assemble the MMU as I needed to
grind the tips of the tube on a trial and error basis)
- used my DREMEL to drill out the holes in the MMU (2mm)

I worked as long on these changes until I was able to push the filament BY HAND thru the MMU and into the extruder without any force.
So far I modifed only filament 1 and 5 as I only need the MMU for soluble support.

After these changes, I performed a complete reset of the printer and used the calibration WIZARD to re-calibrate the printer and MMU.

RESULT : I was able to finish calibration FIRST time after weeks of troubleshooting. 😮

I'm curious to see if I now will be able to do a first print.

Posted : 18/12/2018 3:34 pm
joreal
(@joreal)
Estimable Member
Re: MMU2 - will it ever work reliably ?

Is this survey reliable? In my own opinion majority of those people browsing Original Prusa i3 MK2.5/MK3 Multi Material 2.0 Forum are those who are encountering issues with their MMU. If I had no issue with my MMU2.0, I won't be browsing this forum. Now I seldom check this forum after I fixed my MMU2.0.

...
Posted : 19/12/2018 4:44 pm
Nikolai
(@nikolai)
Noble Member
Re: MMU2 - will it ever work reliably ?


Is this survey reliable?

Of course not :). It's just showing that you have people in this forum who are using their MMU2 on regular base and reliable. And you also have people here who are struggling with it.

Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram...
Posted : 19/12/2018 6:48 pm
dryja123
(@dryja123)
Honorable Member
Re: MMU2 - will it ever work reliably ?

Happy to see that Josef sent out an official survey today. I provided my honest critical feedback.

I'm really happy that they're finally asking their beta testers.... I mean loyal customers for feedback.

Posted : 19/12/2018 6:57 pm
JuanCholo
(@juancholo)
Reputable Member
Re: MMU2 - will it ever work reliably ?

the single biggest issue is the prusa provided Spools that currently come with the MMU2. there are now some good options with regards to this issue.

the next issue is having to hand machine certain parts of the MMU2 for smooth filament travel during loading and unloading.

this at least allows you to start to evaluate different Filaments and how they react in the machine.

no matter what there will always be the possibility of things going wrong. You get this with a standard single filament printer as well, but with this style of multi-material printing where you are saving money reusing a single extruder the additional complex mechanical dance required to change filament in and out of the machine increases the chance of failure.

going down the list of problems. the Firmware is still very buggy and needs a couple of big issues fixed right now 1.0.1-1.0.2 really fixed things and 1.0.3 is better with the power recovery but there is still some big problems that need to be fixed ASAP for 1.0.4

“One does not simply use a picture as signature on Prusa forums”...
Posted : 19/12/2018 7:47 pm
joreal
(@joreal)
Estimable Member
Re: MMU2 - will it ever work reliably ?


Happy to see that Josef sent out an official survey today. I provided my honest critical feedback.

I'm really happy that they're finally asking their beta testers.... I mean loyal customers for feedback.

Yeah. That’s a good move from Prusa. I will do it later, I just woke up only this morning (here in South East Asia).

“Beta testers” ... hahahaha.

They also updated their manual(haven’t browse it yet).

My Mk2.5+MMU2.0 is running fine and reliable after 2 months of debugging and my Palette 2.0 arriving this week or the other week. But if you ask me which one I prefer, I will choose Prusa MMU2.0 because it is more compact in design.

My overall experience with MMU2.0 on MK2.5 was horrible BUT WITH HAPPY ENDING.

...
Posted : 19/12/2018 11:41 pm
joreal
(@joreal)
Estimable Member
Re: MMU2 - will it ever work reliably ?

MY TROPHY!

...
Posted : 20/12/2018 12:57 am
joreal
(@joreal)
Estimable Member
Re: MMU2 - will it ever work reliably ?

Sorry, I posted the picture here. Posted on wrong forum topic but Im not going to delete it anyway.

Originally intended to post in the forum topic titled “Is is worth it?”.

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Posted : 20/12/2018 2:08 am
jon.d4
(@jon-d4)
New Member
Re: MMU2 - will it ever work reliably ?

Hell No. After multiple attempts I can't even get mine to load filament properly. The slicer blade mount alone is a TERRIBLE design that doesn't cut and is more likely to rip itself out of it's mount as it is to do anything useful.

I'm sure the MMU2 is a clever design. But it's too clever and too much trouble. Do not buy.

Posted : 21/12/2018 3:51 am
joreal
(@joreal)
Estimable Member
Re: MMU2 - will it ever work reliably ?


Hell No. After multiple attempts I can't even get mine to load filament properly. The slicer blade mount alone is a TERRIBLE design that doesn't cut and is more likely to rip itself out of it's mount as it is to do anything useful.

I'm sure the MMU2 is a clever design. But it's too clever and too much trouble. Do not buy.

Regarding the blade, as far as I know it is currently not in use. You might be having issue with retraction from selector.

Try running dummy mode where the orange ptfe tube is disconnected from extruder. This will isolate the source of your problem.
a. No jamming --> problem is at extruder side. You might have issue on filament tip after ramming or try calibration if you haven't done it.
b. Jamming --> problem is at MMU side. Fine tune drum, align gear, fine tune sensor, check selector hole condition(you might need to widen it or print modified version from thingiverse).

In my case both have issues so I focus on MMU side first then when it was running fine I then focus on extruder.

Running dummy mode will simplify your debugging. Try running 3d model with more colours per layer.

...
Posted : 22/12/2018 6:44 am
toaf
 toaf
(@toaf)
Noble Member
Re: MMU2 - will it ever work reliably ?

it works fine without the blade

I have a Prusa,therefore I research....
Posted : 22/12/2018 7:14 am
Martin_au
(@martin_au)
Reputable Member
Re: MMU2 - will it ever work reliably ?

The poll doesn't match the thread title.

As for the thread title.
"MMU2 - will it ever work reliably ?"
The answer to that is almost definitely, "Yes".

The MMU software is currently inadequate, and there are some hardware aspects that can be improved. However, the design concept is pretty solid. Once they update the software to re-enable the filament sensor, and tidy up a few potential jamming spots. Perhaps rejig the blade so it's more effective at cutting off rogue strings, then there is little that can go wrong with an MMU.

Posted : 23/12/2018 1:26 am
jason.r10
(@jason-r10)
Active Member
Re: MMU2 - will it ever work reliably ?

After much pain … and the removal of the filament spoolers mine is now working I also cut down the PTFE tubes into the MMU
..I am letting gravity take the slack on the retracted filaments with a bearing as a weight.
An hour in and its still working fine ....fingers crossed

Posted : 23/12/2018 6:44 pm
dandrewe
(@dandrewe)
Active Member
Re: MMU2 - will it ever work reliably ?

I think saying that "it works for most people because only the people having trouble are posting here" is ridiculous. There will obviously be a bias towards people having trouble on the forums but we don't know how many of these were sold, and even the people who have managed to get their MMU 2.0 working reliably generally seem to say that it took a lot of tweaking/troubleshooting.

I don't know how many MK3s have been sold, but the MK3 general discussion forum seems active and most of that is general discussion and not people talking about how much trouble they're having. Looking at the number of views for the topics in this or the other MMU 2.0 forums it doesn't look like there are that many MMU 2.0s out there.

Anyways, I think the MMU 2.0 could work reliably. People have gotten theirs working, so I see no reason that more work and tuning of the firmware on PR's part could make this better for more people.

In my personal opinion, this whole thing has left a real bad taste in my mouth. I really think that the MK3 is great, but the idea that I paid $300 for this in comparison makes me bristle.
Especially with the whole "spool holders" thing which to my knowledge was literally never disclosed before release, because I literally would not have ordered this if I had been aware of that.

Posted : 28/12/2018 8:42 pm
dryja123
(@dryja123)
Honorable Member
Re: MMU2 - will it ever work reliably ?


I think saying that "it works for most people because only the people having trouble are posting here" is ridiculous.

Especially with the whole "spool holders" thing which to my knowledge was literally never disclosed before release, because I literally would not have ordered this if I had been aware of that.

I agree with you 100%. By making that argument they're also saying that the mass who have theirs working properly never browse a forum to see if there are any improvements out there. Those who have their units working properly would also see these threads and share their experience. They're certainly the minority at this point.

Posted : 30/12/2018 6:53 pm
raphi
(@raphi)
Trusted Member
Re: MMU2 - will it ever work reliably ?

Hello,

I recently began printing again and was thinking about going for the MMU2, either by 2.5 or MK3, I haven't decided yet. And after stumbling over this and similar threads I begin to question if I should go for the MMU2 at all or just stick with my MK2/s MMU1.

What I try to understand is if the problems people have are similar to the ones with MMU1 (i.e. manageable) or if there are serious design weaknesses at play. It took me some time to get my MMU1 running properly but I didn't have to do something drastic like drilling, all it took was to calibrate it right, find the right temperatures for my filament, some fiddling with the springs, playing around with different retraction settings and lastly a modified GCODE end-part someone posted on the forum eliminated almost all fillament problems.

I'd be willing to go on a similar adventure for the MMU2 to get it working but I want to eventually have it going within a reasonable amount of time. My MMU1 is quite reliable and filament gets only stuck very rarely, I had 4-colored prints running on my MMU1 for over 20hours without problems, is that kind of reliability achievable yet with the MMU2?

It'd be a bummer if not because my primary motivation is to get an MK3 or MK2.5 for the magnetic bed but I also want to print multimaterial, which I understand is only possible with MMU2, or not?

...
Posted : 08/01/2019 10:12 pm
Nikolai
(@nikolai)
Noble Member
Re: MMU2 - will it ever work reliably ?


What I try to understand is if the problems people have are similar to the ones with MMU1 (i.e. manageable) or if there are serious design weaknesses at play...

It always depends who you ask. If you went through MMU1 hazzle, you know already all the proper temps for your filament. So you would definitely benefit from this knowledge. For all my first MMU2 prints the stock hardware and firmware worked fine, so I got my multi color gecko and sheep the same day I assembled the MMU2. But it also took some time to understand the rare issues with the filament path and spool holders.


I'd be willing to go on a similar adventure for the MMU2 to get it working but I want to eventually have it going within a reasonable amount of time. My MMU1 is quite reliable and filament gets only stuck very rarely, I had 4-colored prints running on my MMU1 for over 20hours without problems, is that kind of reliability achievable yet with the MMU2?

It'd be a bummer if not because my primary motivation is to get an MK3 or MK2.5 for the magnetic bed but I also want to print multimaterial, which I understand is only possible with MMU2, or not?

Correct. MM on MK2.5 and MK3 can be only done with MMU2.
If you're reading all the negative posts, try also to read the positive ones. For example:
https://shop.prusa3d.com/forum/others-archive--f58/successful-mmu2-prints-t25633.html
https://shop.prusa3d.com/forum/general-discussion-announcements-and-releases-f53/mmu2-real-multi-material-t26839.html

You will find there prints with 24 hours+ print time on MMU2.

Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram...
Posted : 09/01/2019 12:16 am
toaf
 toaf
(@toaf)
Noble Member
Re: MMU2 - will it ever work reliably ?

"You will find there prints with 24 hours+ print time on MMU2"

24 hours is like that 1000 tool changes.. kids play 😀

I have a Prusa,therefore I research....
Posted : 09/01/2019 12:26 am
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