I'm done  

RE: I'm done

@nikolai-r

I'm on those FB groups.  Its the same stuff. Doubly so for those of us who bought it to print mixed material for supports.

As for "Manual intervention is part of this design." Source? I ask because to say "this was designed to specs that will require the user to regularly intervene and correct errors" seems far fetched or an admission that the product isnt ready. 

RE: I'm done

WOW do I understand your frustration.

I have had my MMU2 for well over a year and have never been able to get a single multicolor print.

Not only that it made my printer a piece of garbage.

I had found a 3D printer repair guy and had him look at it a few times but he could get it to print a 3 color lizard, me still nothing.

Just trying to use it as a single color printer and the MMU was making every load a chore.

One night Im at work trying to load a filament and start a single color print, I tell my wife im leaving in 5 minutes, 45 minutes later I still had not been able to load the filament. At this point I was only trying to print with prusament, but no.

I literally backhanded the machine and the MMU snapped both of its attachments and bit me pretty good as well.

I called the 3D printer repair guy and he found problems at least one was deep inside the MMU. I have had it back now for almost 2 weeks and it is truly amazing. When we got it back we immediately started a 3 color lizard. The first multicolor print to print successfully for me. I then printed a 5 color Spongebob for my son and it printed amazingly well. I have been printing non stop multicolor and single color prints and it is truly amazing. Gone are the MMU needs attention errors. I am truly amazed that I just print from SD and select a filament and it just works.

Believe me Im not bragging, Im just trying to let everyone know that it is possible, it just took someone who knew much more than me to make it work. I am just a happy customer of LA 3D Printer repair. Lee never gave up and was not satisified until I was happy. You gotta love service like that.

RE: I'm done

@ira-g

Good for you but could you ask your repair guy what problems he has found exactly and how he has resolved these.

Many thanks, hope you / the repair guy can help others resolve their problems.

Greetz Chris

RE: I'm done

Posted by: @ira-g

WOW do I understand your frustration.

I have had my MMU2 for well over a year and have never been able to get a single multicolor print.

Not only that it made my printer a piece of garbage.

I had found a 3D printer repair guy and had him look at it a few times but he could get it to print a 3 color lizard, me still nothing.

Just trying to use it as a single color printer and the MMU was making every load a chore.

One night Im at work trying to load a filament and start a single color print, I tell my wife im leaving in 5 minutes, 45 minutes later I still had not been able to load the filament. At this point I was only trying to print with prusament, but no.

I literally backhanded the machine and the MMU snapped both of its attachments and bit me pretty good as well.

I called the 3D printer repair guy and he found problems at least one was deep inside the MMU. I have had it back now for almost 2 weeks and it is truly amazing. When we got it back we immediately started a 3 color lizard. The first multicolor print to print successfully for me. I then printed a 5 color Spongebob for my son and it printed amazingly well. I have been printing non stop multicolor and single color prints and it is truly amazing. Gone are the MMU needs attention errors. I am truly amazed that I just print from SD and select a filament and it just works.

Believe me Im not bragging, Im just trying to let everyone know that it is possible, it just took someone who knew much more than me to make it work. I am just a happy customer of LA 3D Printer repair. Lee never gave up and was not satisified until I was happy. You gotta love service like that.

 

LA 3D Printer repair as in Los Angeles? I'm in Orange County, I could take it there and have them fix it.

RE: I'm done

He is actually located in Arcadia, CA just outside of Los Angeles.

RE: I'm done

Yeah, I looked into them few months ago - just before I yanked MMU2 off. They built lot of MK3S's. I wasn't sure if they'll fix the MMU2 so I passed it. Now, with your experience with them that got me wanting to take it to them. 

RE: I'm done

I can’t say enough good things about them. Lee was determined to make sure it worked and I was happy 

RE: I'm done

I am done as well, I have been on the github in the past about this. 

Tried to fix it for months. 

Have a 1:1 ratio of failures to success.

Have 1 single MMU print success. 

Too many failures to want to continue.

Left the printers aside for months hoping it would be corrected in the firmware.

Now after a 6 month hiatus, updated the firmware from the December updates.

The MMU was poorly engineered, it incorporates to many changes compounding points of failure.

In order: 

1) Extruder Fan cable tearing 

2) filament loading malfunctions.

3) MMU loading motor failures 

4) MMU selector motor failures

5) IR sensor failures

6) selector blade slippage 

7)  I could go on. 

Conclusion, I am ripping off the MMU2 and setting it back to the mk3 and manually switching filaments. 

RE: I'm done

Oh wow i just got my mmu2s today and build it. It did do the selector mod en the ptfe tube festo mod. But I already printed the 2 colour torture test and one other test print. But it actually worked right away i have to succesful prints now.

RE: I'm done

The sensor is responsible for 99% of the incorrect behavior of the MMU2S. The MMU2S sensor communicates with the extruder sensor. If one fails, this leads to the problems mentioned above. There are good updates for the extruder, e.g. the "chimney" variant. The MMU2S should be checked for filament residues in the sensor area and cleaned if necessary. Correct setting of the MMU2S sensor, spring tension on the drive gears is just as important as the precision when assembling the MMU2S. Despite everything, the MMU2S can of course still be optimized, including the principle of the Wipetower.

RE: I'm done

What is the right tension for de extruder drive gear with the new tower? How far should we screw in?

RE: I'm done

What is the right tension for de extruder drive gear with the new tower? How far should we screw in?

RE: I'm done

@ruben-w

It depends on the filament. I would first tension the spring only 1 1/2 turns and starting some tests. If necessary, retighten the spring a little until the filament is loaded and unloaded correctly.

RE: I'm done

@drew-b4

I bought the mmu2s  May 2019. I did everything i could. Printing modifications using skinnydip or dribbling methods. I could never get the tips right in order to achieve even one successful print. Skinnydip and dribling method helped by improving the tips a bit but still i needed too much tweaking and almost always an intervention.

What helped though was the reduction of ambient temperature. I live in Cyprus where summer spawns from May to October and  temperatures reaching 40 degrees. The last two months without changing anything on my mmu2 and only because the ambient temp is significantly lower, i get almost every time very good tips and successful intervention free prints. I tried it with PLA and VBOH and PETG and VBOH . At the one hand im happy that now i cant print using mmu2 but on the other hand this product is prone to even the slightest variable change. Yes one of the main reason of failure are the filament tips but those can are sensitive to a lot of parameters.

Finally all this loading and unloading causes a lot of delay, and sometimes even tripling the printing time. This along with the fact that for a lot of us is not trustworthy and needs babysitting makes it a not so good of a product. A 10 hours print that turns to 24 and fails at halftime is not efficient. I hope they follow a different approach on the new core-xy printer. I know that for a lot of people it works. But for a product to be a success it should fail for fewer customers that the ones we read in the forums.

RE: I'm done

Also what I just found out. Whenever you have a filament load or unload faillure. You have to take out about 30cm of filament and throw it away. Beceause the gears will have dug a hole in the filament and you will keep having issue next load and unloads beceause you constantly come across the same hole. 

RE: I'm done

Actuallly it says it here in the video:

https://forum.prusa3d.com/forum/original-prusa-i3-mmu2s-mmu2-assembly-and-first-prints-troubleshooting/mmu2-button-functionality/

RE: I'm done

Just finished my second mmu2s print the 3 coloured lizzard in pLA (8 hour print with lots of tool changes). I only had 2 load fails. For the rest it printerd perfect. I did do a lot of mods right away:
-Slightly larger ptfe to the extruder and the 5 small pipes in mmu.
-Cooling fan on the mk3s extruder motor, that got to hot for my likings the first MMU print yesterday
-Updated selector with the magnet and the Pinda hole
-Updated m10 passthrough fitting on the selector
-Updated m10 passthrough fittings on the back op the unit to slide in the 5 ptfe

With these mods its seems to be working ok on pla.

RE: I'm done

@ruben-w

Mechanical mods are just half the way. You Need also to be careful About the tips. See also :Tips on unload

RE: I'm done

I fully agree with the original post.  Prusa should pull this off the shelf.  While I know there are people who can get it dialed in and working fine, I was not one of them.   I have 40 to 60 hours into experimenting with different settings to fix filament tip issues as discussed on the "MMU2S filament tips on unload" thread.  I had 4 of 5 filament colors dialed in on Sunday.  And in a print last night, everything was screwed up again.
I have made many hardware mods.  I have tried countless filament and printer settings.  Prusa chat support said I was trying all the right things.
I'm removing my MMU2 tonight, and going back to single color printing.

If you are thinking about buying the MMU2.  Don't.

RE: I'm done

me too - the product is half baked . i am rolling back. It will suddenly say the fialament is ejected - no reason . 5 times in a row !!!  I hate printing .