At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.  

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

@apromain

The key for me was to understand what’s happening in the firmware and not only hardware. You can’t really see the different error states by the blinking indicator 

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

Actual info from my MMU2S:

• still without cooler fur extruder motor (will be next week = too much work in the office)
• still with lower retraction = 0.6 mm
• still with standard buffer + PTFE fittings PC4/M10 MOD

Results:

• 10+ hours prints without any issues (single color)
• 5+ hours prints with 2 colors
• 3rd color/slot was big issues last weekend and I discovered a problem with a buffer / 3rd slot = too much traction in it. I haven't time to solve it, so, for now, I don't use a buffer for the 3rd slot. I have REPBOX2 for filaments so I ordered parts to build their REPWinder:)

Conclusion:

• Everything you all have written in the last weeks is 100% true. MMU2 can be a nightmare and you have to tune it to a working machine...
• It's a shame that these MODS are not suggested by PRUSA on their GUIDES as strongly recommended... Should be sticky in all forums, help pages, etc.

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

@jagr_200

Hi, sorry but I'm not selling it.  That seems to be a common response on many forums 'having trouble?  Wanna sell it?'.  I just want to get it working and performing it's purpose rather than offload it.

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

@nikolai-r

I have sat and watched it through a number of prints, so I can track exactly what it's trying to do, why, how and when.  When it does fail, it's not very intuitive.  The error light sequences and purpose of the MMU2S buttons seems a bit of a dark art.  I have ordered 5 reels of Prusament now, as I find that it seems to perform a lot better than other manufacturers (ymmv), and it works great in single filament mode (obviously).  As the price of Prusament is now a lot more competitive with alternative brands, that may be my way forward.

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

the lights and button functions are all documented in the MMU2S user guide ( they do change depending on the MMU's current mode)

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

@david-a66

Hi David, many thanks.  I found the information I was looking for, but not in the hardcopy manual, was on the on-line help.  It just seems to me that on many forums (and not just this one), it's a bit like insulting the mafia.  If you even tangentially question the product, you may as well be insulting the nearest and dearest of fellow posters as people seem to take things very very personally and not objectively.  I'm not pointing my finger at you, nor any others on this forum thus far, but it has been my experience elsewhere.  In this case it was a case of RTFM, just a case of finding the correct 'M' to 'R'!

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

The MMU2s is definitely not for the faint of heart, there are a lot of pieces that have to go together correctly and even if done perfectly you can still have problems. My MK2 and MK3 have worked near perfectly over several years, so I think there is an expectation that a properly assembled MMU2s will be the same however that's not always the case for a variety of issues such as filament characteristics. However when properly working it works very well and is a very inexpensive way to print multi-filament.

All that being said, it's also the case that people don't take the time to assemble it correctly. When you read the comments in the instructions it's obvious people are not following directions, taking shortcuts or making mods before they ever get it working. I am not shocked that people have issues after you read comments like:

"I tightened mine too much as I didn’t read all the way down the instructions before proceeding. I cracked it and tried to glue it, but I believe the crack was exacerbated by tightening the two tension spring screws down too far on the idler assembly. Because the screws were loose on the extruder motor shaft due to the crack, the idler was shifting off the filament and not allowing the gears to grab it sufficiently to either load or eject properly" [Using a cracked part instead of printing a new one]

"M3x10 screws didnt work for me for the top two holes, I had to use M3x14 screws for them." [Wrong screws used, may interfere with other parts and will again use the wrong screws later where it requires the M3x10]

"I flared the ptfe tubes behind the selector on all 2 parts and now it's much better. I don't understand why you insist on saying that they are flared only on the outside" [Modding the design before it's even working and not even knowing why]

"After some jams during assembly I also had to use superglue." [No directions anywhere ever call for gluing components together]

"The thermistor I got is a cartridge with a short “pigtail” connector" [Using after-market non-Prusa parts and complaining it doesn't have the correct connector.]

There are hundreds of quotes like these, and these are only the people that post. Who knows how many others are not assembling correctly. Folks should remember that it pays to go slow and carefully the first time or you may be setting yourself up for failure down the road.

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

I assembled my MMU2S from a kit I bought 'open box' from someone else here in the States who decided not to use it.  It was totally unused and complete except he had saved me the calories by swiping the bears.  😉

Yes, I RTFMed very carefully before and during the assembly looking at the photos on a tablet very explicitly while putting it together.  Before assembling I also printed a couple of the versions of remixed filament sensor flags as some reported trouble with it.

I can honestly say that it worked the first time, other than the learning curve issues.  It takes some patience and attention to detail to get it right.  In particular I had no issues with the filament sensor.  '1' and '0' exactly as they were supposed to be.

The only thing I've printed so far in true multi-color are the test 'pucks' and the sheep, all which came out fine.

The only real issue I had was when I unloaded, or attempted to unload all the way to the reel, a filament that had a bit too large of a 'blob' on the end, and it jammed in the tube.  It required disassembly and careful coaxing to get it resolved.  Again, learning curve.

Right now I have it disconnected, in place, with the power connector pulled.  I plan to use it when I need it, for multi-color and for soluble supports.  I'm collecting the pieces to do a few mods before I permanently put it in place.  Things like ...

Bowden fittings on the input.  I have all of the pieces now, just have to assemble.

Large orange PETG knobs on those two tension screws.

Switch and housing to turn off the power to the MMU2S.  I have this printed, the switch just arrived, and I have to assemble.

One thing I did right off the bat is to make a 'base' (remixed the Prusa piece) to allow the buffer to stand vertically behind the printer.  This is due to the space on the counter in my office where I have the printer.  I also did two brackets to direct the input tubing upward toward the spool rack.

When I get this all set up, I want to start playing with soluble supports, particularly using the soluble filament only for the interface.

However, I plan for most of the work to be done using it without the MMU2S.  I've found it to be much easier, for single color work, to simply load the filament directly instead of selecting it and having the MMU2S load the requested one.  I've found it to be very easy to load the filament by pressing gently on the 'flag' piece to start the gears turning to load the filament.

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

Posted by: @jsw

When I get this all set up, I want to start playing with soluble supports, particularly using the soluble filament only for the interface.

Before using expensive soluble filament, you can try to use PLA/PETG combination as they don't stick well to each other.

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

Thanks, I may just try that.

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

"This amount of tinkering shouldn't be needed."

Mantra for all prusa products except the MK3S.

Should have ended on a good one.  I have two dead minis, and I just put together the MMU2S for myMK3S and came across this thread.  Here's hoping I got a product that works :-/

The new XL looks awesome, but it costs 13 arms and 7 legs.  Thaaaanks Josef.

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

I have the same problems with the position of the MMU selector. The position one light will be on and it is sitting at number 3 and so on. The MMU never knows where it is and never resets after a problem. Just sick of reading forums for fixes on so many issues. It is funny that I can print five different objects in all five colors (not at the same time) with no problem but if I try to print one object with five colors it will crash every time. Love the MK3S but the MMU is a major problem.

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

More information would be crucial to identify your problem. When exactly does it happen that your selector gets out of sync? When you start up your printer and the MMU, does it calibrate correctly and move to the position it shows (and does the filament move unobstructed at that position? If so, than the startup is not your issue. Like I mentioned before check if all screws, especially the selector grub screws, locking the selector in place on the selector axis are tight in place, that means it is absolutely impossible to turn the selector without turning the motor by exactly the same amount. If you can identify a precise event where the out of sync move happens, what is predating that move exactly? Is there any load/unload complication predating it? If so, check the reliability of the two filament sensors.

 Those are just some major points, of course there could be another problem causing your out of sync selector but for that one would need to know more about what is happening exactly. 

The MMUS causes a lot of issues when one thing is not working reliably. 

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

We are slowing getting the issues worked out but we did notice Filament is one of the big issues. If you find one that works then stick with it. We love Prusa filament but the cost for shipping to USA and higher price just is not in our budget at this point. It  is a very steep learning curve for the MMU. My son wants to buy our printer at full price. We are thinking about it so we can get the XL once we know others are printing with it without any issues. I must say there is a lot of information on the forums that will help. Still a lot to learn but we are getting there. Thanks for all the info.

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

How is it capability of working really well even? Even I get the MMU to load and the filament to make it to the nozzle, both sensors are showing it is loaded. I tell to do a first layer height, and it heats, does bed leveling, and then unloads the filament and all the red lights start flashing on the MMU and then must start over and it does the same thing. 

RE: At what point do we get actual help from prusa for the MMU2S? Tons of constant issues.

The MMU works terribly as long as you have major issues. Don't even bother trying to make it through larger prints as long as you have not resolved them. 

The MMU refuses to fully load the filament to the nozzle and purge if there is too much resistance at the nozzle. That is however usually only the case if you have clogging issues and doesn't involve flashing red lights. 

All red lights flashing is something I know only if the MMU is trying to move the selector but can not do so because it is blocked (usually because there is still filament loaded or remaining filmament or strings blocking the selector physically. 

If you restart the entire MK3s+MMU2s, does it startup properly with no red lights? If you then press any of the middle button on the MMU long enough until it starts doing something, does it home properly and then have one red light flashing? If so it is acting as it should and tries to load the filament in the position the selector is in. If you preheat the nozzle in printer settings and then load that filament channel to nozzle, does it do so as it should without any error lights or messages?

One thing that is important. Before you start an MMU print, unload any filament currently in the nozzle, even if you have the one path loaded it actually needs first. If you start a test MMU print, what happens during the first load? Does it load properly and do the priming line or do you get this weird unload and then flashing all red lights right away?