MMU2S not ready for public use  

Page 4 / 6
  RSS
CybrSage
(@cybrsage)
Honorable Member
Posted by: @jason-n7

@cybrsage

not all of them are "doing the job".. i've had nothing but issues. Prusa has some of the best support, but I have issues trying to print single filament with this, at this point wont attempt a job with multiple.

Please quote me ever saying that (impossible to do since I never said it) or at least be mature enough to admit you made it up.

Posted : 05/03/2020 1:22 am
gnat liked
CybrSage
(@cybrsage)
Honorable Member
Posted by: @nikolai-r

... and still there are plenty happy MMU2 user out there.

There is a facebook group full of them posting pics of successful prints.

Posted : 05/03/2020 1:24 am
jason.n7
(@jason-n7)
Active Member

@cybrsage

It is possible that i hit reply to you mistakenly.. however, "calling me out" does about nothing.. Get over yourself.. its one thing to point out error, but this isn't twitter war and we're not trying to be "cool".. I could care less about playing in your sandbox or your status as a forum member. Good luck with your prints and hope you have a nice evening! 

Thank you!

Posted : 05/03/2020 4:58 am
stuart.b4
(@stuart-b4)
Estimable Member

My chief problems with the MMU2 can be considered to be that you need to see a working one to fully understand it. Troubleshooting it is hard without a base of reference.

FWIW my problems/solutions:

  • Filament provided with printer went massively out of spec mid-way through the roll - well over 2mm wide.  I lost many hours to this.
  • The PTFE in my hot end was too wide - my tips were allowed to be huge leaving the extruder and would get caught unloading.  Replaced it with Capricorn.
  • Buffer - Ditched
  • Upgraded to MMU2S
  • Fiddled a lot with FINDA and extruder filament sensors a lot to get "just so"

In summary that's it - I really haven't done much to it. My remaining issues:

  • I have to bypass it to print Flex.
  • PVA supports strings on change and tends to make my wipe towers fail if I don't intervene (with taping the tower to the bed!)

I print 2+ filament objects a lot now.

But... yeah... troubleshooting the MMU without using a working one for a while... is very hard.

Posted : 07/03/2020 2:59 am
jason.n7 liked
robert.k71
(@robert-k71)
New Member
Posted by: @robert-k71
Posted by: @nikolai-r

... and still there are plenty happy MMU2 user out there.

And if there are any in Vienna, I could need (paid) help for my MMU2S.
I'm now tired of trial and error and thought about sticking my arm like John-H76
Posted by: @john-h76

Don't worry, you'll eventually get it to kind of work. If not, you have a $300 paperweight. I may just duct tape mine on my arm and tell people it's a Pip-boy. Either way, people will know you're a baller because your paperweight/Pip-boy will cost more than their fresh Jordand. 🤣 🙄 😭 

...didn´t find help in Vienna, but finally we got it running,
tried different hints, like bigger PTFE tubes, other chimney,
i dissambled some things on the mmu2s, and found either a loose contact on the idler stepper motor or the bolts on the idler stepper...

don´t know which problem it was. 
But finally the mmu2s works very good on PLA, and OK for PETG.

Posted : 01/04/2020 4:43 pm
jiral
(@jiral)
Trusted Member

@dick-v

That is a perfectly viable option but there are scenarios where the MMU can do things which are much harder otherwise or even impossible. When you want to print multicoloured objects with complex colouring patterns which are not visible from the shape, try painting that with a paintbrush. If you then want to also have correct and precise colour patterns that will be quite a challenge.

Another scenario is when you have complex shapes and also colour changes halfway inside cavities.

Needless to say that the MMU is not for everyone but does it have to be?

This post was modified 3 months ago by jiral
Posted : 28/04/2020 7:25 pm
dick.v
(@dick-v)
Eminent Member

@jiral

Hi Jiral, you are absolutely right! Like I mentioned in previous posts it's all about making choices.

The MMU2S is absolutely fine if you want to spend many hours of tweaking around to get it working and in the meantime

learning a whole lot about the possibilities of FDM 3D printing. Nothing wrong with that choice.

On the other hand, to my humble opinion, while running a business to keep my customers satisfied, time is money and being used to the excellent performance of the MK3S the MMU2S is costing me too much time (=money)  to get it up and running without any severe problems.

Posted : 29/04/2020 12:22 am
jiral
(@jiral)
Trusted Member

The MMU is not for business (by far and large). I think we agree on that. It can actually work quite well, sometimes even without a lot of tweaking it is also a bit of a gamble. All in all it is however best for tweakers and hobbyists which can do awesome stuff with it. No one counts the hours there.

If time is money and you really need a reliable colour 3D print, think big or do it completely differently.

 

This post was modified 3 months ago by jiral
Posted : 29/04/2020 6:45 pm
j.j..g
(@j-j-g)
New Member

@roy-r3

I want to follow your advice from June 03, 2019.  Regarding your suggestions, I have purchased the 2.5 mm tubes and I hiave found the “PTFE tube holder for the back of the MMU” On Thingverse, but regarding the

  • Take out the blade or print yourself the enhanced version from Thingiverse
  • Print the auto rewind Spools, also available on Thingiverse.

 I found multiple options. Is there one each you have tried and works better than others? 

Thank you for your contribution. I look forward to “tinkering with mine” until it works. 

JJ

Posted : 07/05/2020 11:59 am
jason.n7 liked
Anachronist
(@anachronist)
Trusted Member
Posted by: @roy-r3

My MMU2 succeeds 99,9% of all prints, here is what I did (and yes, I wrote this a couple of times in this forum as others did. There is plenty of hints / knowledge availabel, one just need to read the threads):

  • Print the PTFE tube holder for the back of the MMU (can be printed from PLA): https://www.thingiverse.com/thing:3233579
  • remove the orange bowden between MMU and HotEnd as it is by far too tight and replace it with one having 2.5mm inner hole dia.
    It needs to be 360mm long and cut a chamfer at the ends of that tube by the use of a 4mm drill
  • Replace the other PTFE tubes with one having 2.5mm inner hole dia.
  • Check all MMU holes to be clear from any overhanging debris left from printing.
  • Take out the blade or print yourself the enhanced version from Thingiverse
  • Print the auto rewind Spools, also available on Thingiverse.

My MMU2S also now succeeds. I did most of the stuff listed above. In fact, I had printed the PTFE holder for the MMU2S feed tubes even before my MMU2S arrived.

All of my PTFE tubes are 3mm inner diameter (I didn't know 2.5mm existed) and the friction is so low I no longer get filament stuck in the extruder feed tube, which wasn't due to the filament tip, but because the filament was just too damn tight (probably not perfectly round, or had diameter variations) -- but I suspect that merely bending that original feed tube caused the opening to flatten, causing my filament to get stuck.

I haven't needed to touch the blade, but here are additional things I did:

  • Bought a conical reamer to chamfer the ends of the little PTFE tubes in the MMU2S selector. I got this one: https://www.amazon.com/gp/product/B07MJJGK5D/
  • Built auto-rewinders and got rid of the buffer. The buffer works OK but it's a pain to load, and I had no room for it on my desk anyway. Because the feed tubes with 3mm inner diameter have so little friction, I had to modify the rewinder design to keep it from pulling the filament right out of the MMU2S after retraction.
  • Loosened the tension screws on the MMU2S. These are incredibly sensitive. A little too tight and the idler doesn't move properly, which can result in the extruder and MMU2 fighting over the filament with loud jerky movements. Too loose and the filament may not be pushed or pulled through the extruder feed tube properly. My screw heads are level with the plastic surface. If they are even slightly below the surface, I'll get problems.

 

Now everything is working great for me.

This post was modified 3 months ago 4 times by Anachronist
Posted : 09/05/2020 9:28 pm
j.j..g and jason.n7 liked
jason.n7
(@jason-n7)
Active Member

@anachronist

You give me hope and may actually put mine back on the machine 

Posted : 09/05/2020 10:16 pm
Anachronist
(@anachronist)
Trusted Member

@jason-n7 - don't give up. I was about to give up, in spite of having printed the PTFE holder, chamfered out the short selector tubes, built my rewinders, etc.

I was printing that colored gecko, which has a filament change on every layer, and it was getting stuck after the first layer. I would baby sit it, pull out filament, re-cut it, re-load it, press the button and the print would resume until the next change, when it would fail again. Then I had the idea of replacing the extruder feed tube with some of the 3mm inside-diameter tube I had left over from my rewinder project, and suddenly the filament stopped getting stuck, but the extruder and MMU2S began fighting with each other. So just as a random thought I loosened the idler tension screws, and all of a sudden everything started working perfectly. By then it was 2:30 in the morning, so I went to bed.

When I got up, I saw the print had stopped again, not because of the MMU2S, but because of a feed problem in the extruder. But the filament was properly loaded. This was puzzling. When the hotend heated up again, the print completed normally. I have no explanation of what caused it to stop. But I've had no further problems.

Good luck!

Posted : 09/05/2020 11:03 pm
j.j..g
(@j-j-g)
New Member

Ok, first problem solved.

Yes, I had to trim the Extruder IR sensor lever. I found the 360 view of the printer useful and did a section and moved it until it sliced the level right at the sensor and I then saw which piece to trim. Luckily it is in the same plane as the filamets when it was printed. So, I sliced one layer at a time with a fine blade. Tedious, and had to install it a few times and remove it again - but it work. Now I get a reliable switch form 1 to 0 when I watch the sensors and the filament get pushed into the bontech gears. Now, I will tackle the feeds. 

Still wondering which upgrades to print for the blade mechanism and which auto-rewind reals on Thinverse works best. Anyone has any suggestions. I am putting together the Lack V2 enclosure and would like the correct reels vs. The buffer before I proceed further. 

I believe this is what being a “maker” is all about - tweak until you get the results you hoped for.

Posted : 09/05/2020 11:55 pm
j.j..g
(@j-j-g)
New Member

@anachronist

Thank you.

I reamed the tubes too, but I only had a drill bit - I will buy that reamer 

Which auto-rewinders did you find works best, or did you just build 1? 

Posted : 10/05/2020 4:30 pm
Anachronist
(@anachronist)
Trusted Member

@j-j-g - my rewinder dryboxes are my own designs, using a rewinder mechanism I found and modified. I have two designs, which I just published on Thingiverse:

Auto-rewinder stand for Rubbermaid 21 cup container

Auto-rewinder stand for Rubbermaid 16 cup container

Each have their advantages. The 21-cup design seals better (I recharge the dessicant less often) and has a shorter feed path for the filament, but the 16-cup design is more convenient because the filament doesn't thread through the cover.

 

Posted : 14/05/2020 5:28 pm
Yaroon
(@yaroon)
Active Member

This thread is way too long already for anyone to read through all the posts but I just want to add that my MKS3 worked flawless until I added the MMU2S. I could not believe my self-assembled printer turned into something that just did not want to work, not once.

Then I sat down and started checking all the feeding tubes and aligning everything properly... getting rid of the buffer... And now I have no more problems with the MMU2S. I print stuff  with 86 filament changes and they succeed every time. (warping is my problem now ;))

Just to say that MMU2S does really work well... but it takes hours of frustration. I'm thinking people who 3D print really have too much time on their hands... what a time sink this "hobby" is. 🙂

Posted : 18/05/2020 10:51 pm
nikolai.r
(@nikolai-r)
Noble Member

@yaroon

I think the purpose of this thread is more for writing then for reading 😉 

Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram...
Posted : 18/05/2020 11:15 pm
CybrSage liked
Anachronist
(@anachronist)
Trusted Member
Posted by: @yaroon

I'm thinking people who 3D print really have too much time on their hands... what a time sink this "hobby" is. 🙂

I have nearly zero spare time on my hands. That is why I spent a little extra and bought a Prusa printer, because I knew I wouldn't have to spend most of my time tinkering with it and instead use what little spare time I have to design and print stuff. The MMU2S caused me a long night of frustration but after solving my problems (see the couple other posts from me above) it's working fine. I am really glad I got the MK3S+MMU2S instead of a dual-extruder printer, which I'd probably still be fussing with. The MMU2S being able to handle 5 materials is way more flexible than a dual extruder anyway. I don't know how it compares to a Palette as an alternative but I understand the Palette has its own issues. If you need multi-material capability, the MMU2S works well. For me, what made it work well was to replace all my tubing with 3mm inner diameter, use rewinders of my own design instead of the filament buffer, print a feed tube holder using PTFE fittings (the only mod I ever printed for the MMU2S), chamfer the little PTFE selector tubes, make sure the IR sensor is well calibrated, and be real careful about the tightness of the MMU2S idler tension screws.

Posted : 19/05/2020 2:49 am
CybrSage liked
jiral
(@jiral)
Trusted Member

^^ I am quite fond of the open selector mod with magnet mod. It might not be necessary, but especially if you need to print something that is hard to get stringfree all the time, it is a real gain in comfort to have the FINDA ball accessible and visible and the added magent makes it also much more robust against interference by fine strings.

Posted : 19/05/2020 6:05 pm
CybrSage liked
jsw
 jsw
(@jsw)
Reputable Member

I too am climbing the learning curve with the MMU2S.

I will admit that it's kinda finnicky and Rube-Goldberg-ish, but I think I have it tuned to work the way it's intended.  Attention to detail in assembly and operation is imperative!

My only multi-color prints so far were the test "pucks" and the sheep.

At this time I have it disabled, but after I finish with a few tweaks I do plan to put it back in service and use it when I need it.

What I'm doing and have done include ...

Mounting the buffer vertically behind the printer. I printed a replacement 'base' which allows it to stand up, and two tube holders to direct the input to the spool rack above the printer.  This is done.

Bowden fittings on the input to the MMU2S. I did print the replacement piece with the M10 threads, and the fittings are on order.  It's a PAIN to remove this when it's necessary.

Long knobs on the two tension adjusting screws.  This is also done.

Switch to kill the power to the MMU2S so it can be used in the normal single-color mode when needed.  I printed the switch housing already and the switch is on order.

I intend to learn how to use this with the water-soluble support filament, and I'm expecting another learning curve to climb with this.

Posted : 23/05/2020 1:37 am
Page 4 / 6
Share:

Please Login or Register