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MMU2S not ready for public use  

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TechTiger
(@techtiger)
Eminent Member
MMU2S not ready for public use

Assembling the MMU2S was a breeze.  Getting it to successfully print anything has been impossible.   Extremely disappointed with the results ( or lack thereof) that I'm getting.   Single color print of the prusa badge was perfect.   Tried to do the gear in two colors and it works for a while then when it tries to re-load filament 2 it always fails.  It loads it fine the first time, but subsequent loads fail every time.  I know the tip was perfect when the print started which is why it loaded correctly and started the print fine.   Cut the end of the filament when the load failed TWICE and once the print continued, the 2nd time, it failed to load again.  I'm pretty sure the tip of the filament is the problem but why didn't prusa address this prior to releasing it and eliminate this problem?   There's a blade in the MMU2S but as far as I can tell, it never cuts anything.  Why not have it set to cut the tip of the filament prior to loading each time?    I'm beyond frustrated with this after being so excited to get it.      How are people handling these types of issues?

Posted : 01/06/2019 7:14 pm
Thunderhead, Casey, aychbe and 3 people liked
gnat
 gnat
(@gnat)
Noble Member
RE: MMU2S not ready for public use

Did you do your printer upgrade at the same time or were you already running an S?

The results of getting mine working has led me to two conclusions:

  1. The IR sensor working properly is critical and there tend to be issues with the idler door that complicate things. I found it best to make sure you can get through a full print without the MMU connected to make sure the door and tower are working together correctly. 
  2. Your filament path is critical. I found anything that hampers feeding or returning will cause issues with tool changes. I ditched the filament buffer and am using autorewind spools instead, but when I let the spring tension get out of adjustment I'll start having stringing and tool change issues again. 

My advice is to read through the other complaint threads from the last few months. There is a lot of advice and information in them. 

MMU tips and troubleshooting
Posted : 01/06/2019 8:16 pm
TechTiger
(@techtiger)
Eminent Member
Topic starter answered:
RE: MMU2S not ready for public use
Posted by: gnat

Did you do your printer upgrade at the same time or were you already running an S?

The results of getting mine working has led me to two conclusions:

  1. The IR sensor working properly is critical and there tend to be issues with the idler door that complicate things. I found it best to make sure you can get through a full print without the MMU connected to make sure the door and tower are working together correctly. 
  2. Your filament path is critical. I found anything that hampers feeding or returning will cause issues with tool changes. I ditched the filament buffer and am using autorewind spools instead, but when I let the spring tension get out of adjustment I'll start having stringing and tool change issues again. 

My advice is to read through the other complaint threads from the last few months. There is a lot of advice and information in them. 

I was already running an MK3S and have been for several months with perfect prints.  It all went to crap when I started trying to print with the MMU.   If I do a single color print its perfect because it doesn't have to do any changes.  My issue comes with the filament change after the filament has been used once and retracted.  When it tries to load a 2nd time it often fails to load then tells me MMU Failed to load.  No, it really didn't.  The MMU loaded fine, it just didn't load in the extruder like its supposed to be so the print fails.

Posted : 02/06/2019 12:38 am
aychbe
(@aychbe)
Active Member
RE: MMU2S not ready for public use

I wish I could say that I disagree with you but I think you may be correct. Mine is consistently inconsistent. I got it working with TPU and switched back to PLA for a print and now it doesn't want to do either.

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 Jordans. 🤣 🙄 😭 

Posted : 02/06/2019 6:40 am
Casey liked
TechTiger
(@techtiger)
Eminent Member
Topic starter answered:
RE: MMU2S not ready for public use

I just can't imagine these issues weren't vetted before this thing was released for sale.  It would be a little different if I were trying specialty filaments, etc., but I'm just trying to get PLA to load and get through a print. So far, I have zero completed multicolor prints on this thing.  Meanwhile, my Palette 2 Pro and MK3 just hum along churning out perfect prints. 

Posted : 02/06/2019 7:37 pm
Jordan05 liked
Dick V
(@dick-v)
Eminent Member
RE: MMU2S not ready for public use

I agree with eric-b52;

If you are looking for a reasonable multi color FDM option without to much trouble the MMU2s is not the way to go!

If you like to do a lot of research on your own and are not afraid to do a lot of tweaking and trying user mods etc., well maybe.... 

In that case the most important thing is: Time is no issue for you and you love endless trial and error in order to get finally a reasonable result.

Nothing wrong with it if you are aware of it and accept it.

IMO the MMU2s is indeed far from a "ready for public use product", Let's say a alpha release at the most...

 

This post was modified 5 years ago by Dick V
Posted : 02/06/2019 9:48 pm
JNun, Thunderhead, Casey and 2 people liked
Roy
 Roy
(@roy)
Eminent Member
RE: MMU2S not ready for public use

Sorry, I can't agree on that.

Yes, you need to spend some time to set it up correct, remove all friction in the filament path and you also play with the settings in order to get some good tips. But once you did all this, the results are very good.

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.

 

Good luck.

Posted : 03/06/2019 6:59 am
Kevin Rothi and liked
MTom
 MTom
(@mtom)
Trusted Member
RE: MMU2S not ready for public use

This sort of confirms the original post 😉

The MMU2 as it comes from prusa isn´t really ready to use. I think almost everybody did a modification to it to get it to work.

My suggestion is to completely get rid of the tubes feeding the MMU and move the buffer to your recycle bin 😉 replace it with the auto rewind spool holders. The blade is pointless as it only got work to do in case the filament retraction didn´t work out as it should. My one got pushed out anyway so I left it out now.

Besides of that I think the gcode for multicolor wastes way too much filament but that is another story.

Replacing the bowden will be my next step too.

Posted : 03/06/2019 7:46 am
Roy
 Roy
(@roy)
Eminent Member
RE: MMU2S not ready for public use

I agree to throw away the filament buffer.
It adds a big amount of friction to the filament path and in addition changing the filament is almost not doable.
I have my filament hanging on the wall and no kind of buffer in between, works like a charm.
If I take the printer with me, I use the auto rewind spools.
The blade is really useless, untill it got pushed out on its own, it never cut any filament.

You can adapt/reduce the amount of waste with set up under purging volumes/Show advanced settings. But still it is quite a lot of waste.
Or purge into the infill of an object if it is big enough.

Posted : 03/06/2019 10:05 am
TechTiger
(@techtiger)
Eminent Member
Topic starter answered:
RE: MMU2S not ready for public use
Posted by: roy.r3

Sorry, I can't agree on that.

Yes, you need to spend some time to set it up correct, remove all friction in the filament path and you also play with the settings in order to get some good tips. But once you did all this, the results are very good.

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.

 

Good luck.

You say you can't agree, then you provide a laundry list of changes you had to make to get it to work.   So, you completely validated my post above.  Those "changes" shouldn't be necessary to get this to work as it was advertised. This product as it was released to us, was not tested enough prior to being released to the consumer.  I have no problem doing simple calibration steps and alignment steps to get the unit installed just like we did when we built the printers.  We shouldn't have to be printing out different parts and getting different size ptfe tubes to make this work.   With color transitions, these prints can go for days, but the mmu2s isn't going to work for days without needing user attention (at least so far for me).  Hell, mine won't even go for 30 minutes without needing help.      It's pretty obvious the mmu2s has great potential and may actually work as intended....EVENTUALLY, but right now it needs major work.   The only benefit to it for me now is to have 5 colors loaded at once and being able to select one of those colors for a print without having to change spools everytime.

Posted : 04/06/2019 12:23 am
Elvir, Thunderhead and liked
Dick V
(@dick-v)
Eminent Member
RE: MMU2S not ready for public use

I agree with eric-b52,

That's exactly what I meant. If you want to sell a kind of framework which is meant like a DIY toolbox for this community, it's OK!

I am not complaining about the product I received in relation to it's price. It's worth it as long as you see it as a research tool for building up your knowledge and skills regarding multi-color FDM printing.

But I have some serious questions about the marketing communication concerning the MMU(2s). Presenting the MMU2s for disappointed customers of it's predecessors and also giving them a free upgrade from the MK3 to the MK3(s) while showing the testing of it on the Prûsa Blog...

Well, I don't think that's the most smartest marketing approach because we all love the exceptional performance of the I3MK3 single color!

@Prûsa research: Don't push your luck to far, because the silent majority of your disappointed customers will not even reply on this forum... They just quit and will never return.....

On the other side if you see something at a price level which sounds to good to be true..... well, it usually is not....:) There is nothing such as an almost free ride:):) 

I hope you will all see this as a critical but positive feedback.

It's all about managing expectations!!

This post was modified 5 years ago by Dick V
Posted : 04/06/2019 1:00 am
Pixel
(@pixel)
Trusted Member
RE: MMU2S not ready for public use
Posted by: eric.b52

There's a blade in the MMU2S but as far as I can tell, it never cuts anything.  Why not have it set to cut the tip of the filament prior to loading each time? 

if you look at how the blade is positioned and how the MMU works this is exactly what is happening but its not cutting the tips its just cutting what is protruding from the tips so any kind of stringing is cut of every time.

This is the exact reason why the MMU always tries to use alls extruders in sequence and then goes back to extruder one instead of going backwards from 5 to 4 and so on, the move of going from the extruder that is as much to the right side as possible to the first one automatically cuts all stringing of the tips.

Posted : 06/06/2019 6:21 am
tsamisa
(@tsamisa)
Estimable Member
RE: MMU2S not ready for public use

About the constant failing on multiple loading i found out (the frustrating way ) that a slightly deformed PFTE edge inside the extruder in conjunction with it having even the smallest gap with the heartbreak is a constant factor for loading failures. I changed the PFTE and placed a small plastic ring (it  comes on the bowden coupling if you buy a heatsink directly from e3d) reduced significantly my loading problems due to tip deformation.

Posted : 10/06/2019 5:35 pm
TechTiger
(@techtiger)
Eminent Member
Topic starter answered:
RE: MMU2S not ready for public use
Posted by: andreas

About the constant failing on multiple loading i found out (the frustrating way ) that a slightly deformed PFTE edge inside the extruder in conjunction with it having even the smallest gap with the heartbreak is a constant factor for loading failures. I changed the PFTE and placed a small plastic ring (it  comes on the bowden coupling if you buy a heatsink directly from e3d) reduced significantly my loading problems due to tip deformation.

Do you have a link to what you bought?

Posted : 11/06/2019 10:57 pm
Dave Avery
(@dave-avery)
Honorable Member
RE: MMU2S not ready for public use

https://www.thingiverse.com/thing:2478545

Posted : 11/06/2019 11:18 pm
TechTiger
(@techtiger)
Eminent Member
Topic starter answered:
RE: MMU2S not ready for public use

just tried what I think should be a simple 2 color print.   Guess what?   FAILURE...EVERY SINGLE TIME.  

Attachment removed
Posted : 12/06/2019 12:28 am
TechTiger
(@techtiger)
Eminent Member
Topic starter answered:
RE: MMU2S not ready for public use

It would be nice if the mods or admins (if there are any) were active and helping us solve these problems.  But, so far, they are nowhere to be found while we experience nothing but failures with this thing.

Posted : 12/06/2019 12:45 am
Dick V
(@dick-v)
Eminent Member
RE: MMU2S not ready for public use

@ eric-b52;

I understand your frustration as I mentioned before.

The I3MK3s/MMU2s is a great setup for research and education.

There are only a few types of energy, two of them are money and time!

If you want a full blown high end 3D full color printer... just buy one for more then €200.000,-

If you have a lot of time, obvious like the most of the >> "eminent members" at this forum.....:) and like doing FDM researching and

contributing to the "open source" community.... well, just go for it! 

At this moment don't expect a reasonable solution for multi color FDM printing at a very low price from PR.

Nothing wrong with that as long as you are aware of it!!

Posted : 12/06/2019 12:48 am
TechTiger
(@techtiger)
Eminent Member
Topic starter answered:
RE: MMU2S not ready for public use
Posted by: dick.v

@ eric-b52;

I understand your frustration as I mentioned before.

The I3MK3s/MMU2s is a great setup for research and education.

There are only a few types of energy, two of them are money and time!

If you want a full blown high end 3D full color printer... just buy one for more then €200.000,-

If you have a lot of time, obvious like the most of the >> "eminent members" at this forum.....:) and like doing FDM researching and

contributing to the "open source" community.... well, just go for it! 

At this moment don't expect a reasonable solution for multi color FDM printing at a very low price from PR.

Nothing wrong with that as long as you are aware of it!!

But that's the issue I have (and I'm sure many others do as well).  This wasn't advertised as a work in progress or a trial and error device.  This was advertised as a multicolor/multimaterial unit that would work after assembly and it simply DOES NOT WORK.     Filament load problems with every print and the manual doesn't tell you anything about how to correct it.  It says change the temperature.  wow.  How about telling us (in the manual) whether the temperature needs to go up or down to solve the load problems.   Why include a blade in the unit that does absolutely nothing but fall out.  lol.   If larger diameter ptfe tubes are needed for this to work, why didn't it ship with them?   I absolutely LOVE the MK3 and the MK3S printers that I have.  They print incredibly well on their own.  But, add the MMU2S into the mix and the only benefit is having 5 loaded (which I haven't even done yet) to pick from to print a SINGLE color print.

Posted : 12/06/2019 1:09 am
Elvir liked
Dick V
(@dick-v)
Eminent Member
RE: MMU2S not ready for public use

@ eric-b52;

My solution in terms of energy?

Well, take eg. the two coloured sheep and think about your MK3s/MMU2s multi coloured setup......

Case: "You have a customer who wants to have a two coloured sheep and wants to pay for it!"

Solution 1:

- The hard way and trying to get you gear (MK3s/MMU2s) at work....

- You succeeded, GREAT JOB!

- Then you have to print it, how many hours was it.....??

Solution 2: (My way...:)

- Just print it with the superb I3MK3s ONE color, no more

- Take whatever filament you like.

- Pick your airbrush (dual action gear required) with masking tape.

Result:

- <<< less than 10% of the printing time with a full functional I3MK3s/MMU2s multi coloured setup. 

- Totally UV and weather proof ready for outdoor use, even with PLA!!

Frustrated? Learn to think "Out of the box"..:)

- AND.... Customer happy and invoice payed...:)

Posted : 12/06/2019 1:18 am
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