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.

Hi geoffrey-c2, you must have had all the problems that anyone could actually experience. I can sort of feel with you. Reading through your post I am not really convinced you are asking anything of the community. If you wanted help I/we could you help you fix it. It is capable of working really well, just to mention that (and I was at your point 6 months ago).

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

Posted by: @geoffrey-c2

TLDR:  If you haven't bought an MMU2S, don't.  If you have and have problems, good luck.  Prusa support doesn't exist, their email and chat services never have answers, and the only people who know anything about this are in the community.

When I first got the MMU2S, I had the board DOA.  Went through multiple boards and two months of waiting till the 4th board finally worked.  I know 4 other people that had DOA boards.

After I got a couple test prints to work by luck after dozens of failures, I learned to call the MMU-2-S by its proper name "MMU-failed-2-load-S" and I gave up on it.  Now months later I updated firmware and then tried to print a set of 2 color dice, a 7 hour print.  It failed every other load on PLA-PLA two color or PETG-PETG.  I tried different filaments, re-did the gcode from slicer, but it failed to load every 13 minutes or so.

Now I remember why I took it off the printer.

If the MMUever spooks and thinks that the filament is out, it forces that filament to the next slot, so while my gcode said I was using spool 1 for the outer shell and spool 2 for text, it then uses slot 2 for both, which breaks the print.  You CAN NOT re-load spool 1 or fix this mid print from any menu, and resetting the MMU does NOT fix the problem as it messages the MK3S that the filament is out so on the display it clearly says what spool it wants to feed from.

Occaisonally the MMU will get goofed so that the selector is in the wrong position compared to the LEDs.  You cannot re-calibrate its position, your only hope is to manually move it.  Resetting the MMU does NOT consistently fix the problem, because if you confuse it on a max travel it'll go to the "all LEDs blinking" error of death that kills your print with no way to resume.

It continuously over-shoots when loading (I've tried calibrating and calibrating and recalibrating the lengths for the filament between the MMU and the MK3S) so it puts a big glob on the purge block from time to time, and I've watched the filament sensor on the MK3S to see that yes, it sees filament.  This causes the head or probe on the MK3S to crash into the purge block and jump position, nuking your print.  There's no way to fine tune this, and the only solution is to have an offset to length or change the math formula for how it pumps filament between the MMU and the MK3S.

Not literally caused by the MMU, but due to the long delays and heat cycling, the idler screw on the MK3S fused with the nut, causing it to become permanently attached.  The only way to fix this was to disassemble the hot end from the printer and then dremel the nut in half.  A shot on a desktop microscope I got from surplus shows corrosion between the threads.  Users should put anti-sieze on this socket head screw, I know I will now.  I tried even putting the hot end in the freezer before I broke out the dremel, no dice.

Where the tubes go into the backside of the MMU, the part has developed a "step" due to wear, so filaments can't insert and make the gap between the end of the teflon tube and teeth to be loaded and selected.  The only solution will be to disassemble the entire MMU and re-print the main housing.  It has done it on the most used filament slots (1 and 2 are bad, 3 is okay, 4 and 5 are fine still).  No idea what causes this incredible wear on the printed housing.  I guess don't change your filaments?  It means I have to eyeball the filament and load it and then put in the teflon tube in the back of the unit and tighten the screw to hold it in place.

The forums here are a litany of issues I've seen since launch, nothing has been fixed from Prusa.  As evidenced by the new Mini and new main board, I'm guessing there won't be any support for the MMU2S because it'll be obsolete with their next "main" printer to replace the MK3, and likely will use an entirely different setup.

/rant.

I've tried fixes and advice from here in the community, but I've yet to find any solutions that work consistently and make the problems go away.  I think the only solution on a lot of this would be edit the design of the MMU2S housing and try to figure out how to make it work "consistently".  I am shocked people get good prints out of this thing time and again, for me it wastes more filament than it prints.

You get it to work? If not I'll buy it from you.

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

That seems like a fair position :-/

I wanted my mostly single filament prints to just reliably work so I disconnected my MMU2S and am slowly working on getting my MK3S to work reliably and with quality for long prints again before I reconsider enabling the MMU2S again.

The community upgrades and information is amazing and I think I will eventually get the MMU2S working well. I've already printed upgrades to the extruder idler door, MMU & buffer festo fittings, PTFE upgrades. A selector upgrade with the latest firmware may make it usable.

This amount of tinkering shouldn't be needed. The product is way too alpha/beta and should be advertised as such.

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

@egalanos

can you please post list of upgrades your printed/want to use?

(I'm facing issues with extruder stopped extrude in the middle of the print (even in single color print), mainly when there is many retractions)

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

@kumters

Hi Kumters,

I take it you are printing PLA from your description. What you will need to do is to make sure you will have air flowing around your extruder. I specifically describe it like that as the extruder can work reliably under some conditions (mainly A/C or anything that stirs the air a bit). A dead sure solution is an active cooler on your extruder. Works well in any conditions up to 35 °C (tested) and enclosure with PLA.

See lots of community posts for it or even mine.

Michael

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

@egalanos

I agree. The MMU should be more robust. Looking at my solution (which is minimalistic and working as reliable as a MK3s without MMU2s) I can imagine that one could actually do without it. Unfortunately I rather rely on a more robust hardware and I don't have much of an aircon plus I don't want to service the machine after every medium long print. But, as I said, it could work as it is.

As most of us aren't in an industrial environment a bit of fine tuning is required to gain the necessary robustness. Whether that is the responsibility of the manufacturers or ours is debatable. I would have preferred Prosa to do that part of the job, but looking at what it only took I expect this to be part of the MK3.5 in the future. If it wasn't for the hundreds of wasted hours (not especially mine, but as a sum of every user). We should all receive lots of Haribos 😉  

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

@michael-t66

Still with heat-creep. I checked ptfe tube in the head = everything’s ok. I. Checked the temp in enclosure = no more than 24 C (and this problem started before I placed it to enclosure).

As another step I will try to low retraction settings 0.2mm and Then I see. I checked many videos and forums but I’m confused, any suggestion I found are not my case...

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

@kumters

I would still check for heat creep. Look at one of my first posts. Temperature is not relevant, it is rather airflow. Learnt it the hard way, same as you. And the issue is so persistent that you wouldn’t believe it. I hope that it is something different for your sake, but in my experience it would rule this certainty out before checking anything else. 

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

@kumters

By the way, had this in an enclosure down to 22-24 degrees and outside 20-35 degrees. Once eradicated I was able to run PLA at 32 degrees without any problems. 

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

Actually I get first 6cm height print with no problem with retraction set to 0.6mm. And I ordered NOCTUA for that extruder cooler then I will try to move retraction settings back to 0.8mm and we will see:)

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

While I cannot comment on the support help or dead board. I did a bunch of research before building my MMU2S and printed all the recomended upgrades. (Selector with open side and magnet, pc4-m10 through connector adaptor for back of mmu2, pc4-m10 adaptor and pass through extruder body, changed the ptfe between mmu2s and extruder with 3mmX4mm, and a better buffer with bearings, changed all cooling moves to 4 instead of 2). I have been printing for the last two months and I have only had to intervene twice. Both times a 4-6" peice of fillament broke off at the extruder end during retract which is more than likely a error of bad fillament (once PLA and once PVA) other than that the MMU2S has been bullet proof. 

For the heat creep I installed two heat sinks on the side of the extruder motor as many others have and have never had a problem. Currently I have a pla print (10 hours so  far) printing in my enclosure thats closed with no issues. 

Hang in there. When you get the MMU running it becomes well worth the fight!

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

@kumters

Lowering the retraction might help to mitigate the issue as potentially the extruder stepper doesn't have to work that much. So it might give yield the same results, but either passive or active cooling seems the more robust solution.

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

@anthony_davis

Same here: The moment it was all figured out the first machine worked like a band saw. The second one was modified the same way and showed the same experience. Right now or actually since October I expect the machine to be running in the morning and I am pretty surprised (once a month) that it stopped. Half a year ago the expectation was the other way round. 🙂

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

Posted by: @geoffrey-c2

TLDR:  If you haven't bought an MMU2S, don't.  If you have and have problems, good luck.  Prusa support doesn't exist, their email and chat services never have answers, and the only people who know anything about this are in the community.

When I first got the MMU2S, I had the board DOA.  Went through multiple boards and two months of waiting till the 4th board finally worked.  I know 4 other people that had DOA boards.

After I got a couple test prints to work by luck after dozens of failures, I learned to call the MMU-2-S by its proper name "MMU-failed-2-load-S" and I gave up on it.  Now months later I updated firmware and then tried to print a set of 2 color dice, a 7 hour print.  It failed every other load on PLA-PLA two color or PETG-PETG.  I tried different filaments, re-did the gcode from slicer, but it failed to load every 13 minutes or so.

Now I remember why I took it off the printer.

If the MMUever spooks and thinks that the filament is out, it forces that filament to the next slot, so while my gcode said I was using spool 1 for the outer shell and spool 2 for text, it then uses slot 2 for both, which breaks the print.  You CAN NOT re-load spool 1 or fix this mid print from any menu, and resetting the MMU does NOT fix the problem as it messages the MK3S that the filament is out so on the display it clearly says what spool it wants to feed from.

Occaisonally the MMU will get goofed so that the selector is in the wrong position compared to the LEDs.  You cannot re-calibrate its position, your only hope is to manually move it.  Resetting the MMU does NOT consistently fix the problem, because if you confuse it on a max travel it'll go to the "all LEDs blinking" error of death that kills your print with no way to resume.

It continuously over-shoots when loading (I've tried calibrating and calibrating and recalibrating the lengths for the filament between the MMU and the MK3S) so it puts a big glob on the purge block from time to time, and I've watched the filament sensor on the MK3S to see that yes, it sees filament.  This causes the head or probe on the MK3S to crash into the purge block and jump position, nuking your print.  There's no way to fine tune this, and the only solution is to have an offset to length or change the math formula for how it pumps filament between the MMU and the MK3S.

Not literally caused by the MMU, but due to the long delays and heat cycling, the idler screw on the MK3S fused with the nut, causing it to become permanently attached.  The only way to fix this was to disassemble the hot end from the printer and then dremel the nut in half.  A shot on a desktop microscope I got from surplus shows corrosion between the threads.  Users should put anti-sieze on this socket head screw, I know I will now.  I tried even putting the hot end in the freezer before I broke out the dremel, no dice.

Where the tubes go into the backside of the MMU, the part has developed a "step" due to wear, so filaments can't insert and make the gap between the end of the teflon tube and teeth to be loaded and selected.  The only solution will be to disassemble the entire MMU and re-print the main housing.  It has done it on the most used filament slots (1 and 2 are bad, 3 is okay, 4 and 5 are fine still).  No idea what causes this incredible wear on the printed housing.  I guess don't change your filaments?  It means I have to eyeball the filament and load it and then put in the teflon tube in the back of the unit and tighten the screw to hold it in place.

The forums here are a litany of issues I've seen since launch, nothing has been fixed from Prusa.  As evidenced by the new Mini and new main board, I'm guessing there won't be any support for the MMU2S because it'll be obsolete with their next "main" printer to replace the MK3, and likely will use an entirely different setup.

/rant.

I've tried fixes and advice from here in the community, but I've yet to find any solutions that work consistently and make the problems go away.  I think the only solution on a lot of this would be edit the design of the MMU2S housing and try to figure out how to make it work "consistently".  I am shocked people get good prints out of this thing time and again, for me it wastes more filament than it prints.

I am right there with you on the whole "upgrade". It isn't worth the struggle that the MMU2S causes. My printer is much worse off than it was before I decided to spend $300+ on a piece of trash to attach to the frame. I thought I was going to love the new enhancement to my printer but it made everything 10X worse. I can deal with supports that I need to break off afterwards if it means that I can have reliable prints again. Waste of time and money.

**********Prusa please update the last parts of your documentation to better reflect how to properly setup the spools and get test prints/calibration going.**********

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

MMU2s was actually a step forward from MMU2. The fact that you don't need to calibrate the length of the tube and the MMU2/MK3s are talking to each other is a huge benefit. On the other hand the chimney sensor require to be perfectly calibrated, otherwise you will have random loading/unloading issues.

I see why people have so many issues to make the MMU2/MMU2s work. There are many things which need to be observed and understood. Even with all the mods out there, it's still an additional device which inserting and retracting the filament into another device all the time. Once you had a bowden printer, you know how many things can go wrong by doing that.

That's why I never recommend people to get MMU2 with the first printer. Only if you're bored with your single filament prints and there are no issues you can't handle with your printer, then you can do a next step going MMU. But I'm glad we can buy MMU2s for such a low price tag. Otherwise I wouldn't print MMU at all.

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

Posted by: @nikolai-r

I see why people have so many issues to make the MMU2/MMU2s work. There are many things which need to be observed and understood. Even with all the mods out there, it's still an additional device which inserting and retracting the filament into another device all the time. Once you had a bowden printer, you know how many things can go wrong by doing that.

It's been awhile since I got mine working happy, but I still think there is some fault on Prusa here. They have a stellar reputation for their printers just working. Based on what I continue to read a year in I am still thrilled that I went with a MK3 as my first printer. It has given me very little trouble and what trouble I have had has been easy to support.

Where I think this is a problem for the MMU is that Prusa doesn't make it clear that this is still a Beta level product that requires time and effort beyond just the assembly. I think it's a great unit and I can see the improvement from the 2 to the 2S (though most of the advancement was due to the MK3S IR sensor), but it is still far from a plug and play product. I trust that they'll continue to improve the product over time (after all, the MK3S is the result of many more years of development and usage than the MMU has yet seen). If they make the current status more clear up front I think they'll sacrifice a few orders, but there will be fewer posts calling the unit garbage.

As far as the title subject of the thread, I've only reached out to support for hardware related issues (dinged up PEI sheet with my printer and missing cable with my MMU). Otherwise I come here to get support as there are lots of helpful people with lots of real world experience and advice based on that.

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

I echo Gnat's sentiment, the MMU2S simply isn't ready for anyone expecting  an out-of-the-box experience to work correctly. It takes a certain knack to understand what's going on, what's wrong, and get your system tuned and working. Once I got over that hurdle I've done a number of zero-intervention prints and everything seems to be stable.  It's a good item when it works, but definitely lacking on the "significant technical acumen required" warning up front.

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

I joined a forum on Facebook last year to try and get 'help' for my MMU2S struggles - I ended up leaving as I was shouted down for criticising it.  Stepping back a bit, I am a qualified Electro-Mechanical Engineer, 30yrs+ experience, and I am struggling with the damn thing!  When someone on the FB group posted asking whether it was worth it, I posted honestly, with my experiences, stating, as has been mentioned here, that it requires far too much work to make it worthwhile unless you're up for the challenge.  I may as well have been sending death threats to Josef Prusa, with the level ad content of replies I had!  Quite simply, it's not fit for purpose as a plug and play product, and as has been mentioned, is very much a beta product.  I have been running 2 x MK3s' quite happily, and when I purchased the second one, bought the MMU2S.  After 3 or 4 frustrating months, I removed it.  I needed a working printer, and it just wasn't happening.  A few days ago I decided to fit it on and try it again.  I have just had to walk away from the damned thing after a day of playing with it, before I smack it with a sledgehammer.  It's consistently inconsistent.  I have tried different brands of filament, and that seemes to be the key to getting the consistent 'tip' needed, but even then, every so often it just stops and blinks at me.  I follow the help guides for the relevant lights, and it does nothing.  It's like it's challenging me 'hey, Andy, guess what my problem is.....nope, that's not it.....nor that......guess again'.  I've left it for the night now before I lose my rag and smash the damn thing up.  My other non MMU2S MK3S is chugging along brilliantly making money for me, but this one is something else.  I think that's the problem - my first 3D printer was a Creality Ender 3 that I modded like a madman, and it took a lot of work.  Then I bought my Prusa, twice as fast, and worked effortlessly after I had built it.  I think we have that expectation that the MMU2S is going to be the same, but it's far from it.  I hate to criticise Prusa, as they had been helpful to me with other matters, but the MMU2S is just a major disappointment.  I aim to load it up with 5 reels of Prusament, and just see what happens then.  The key for me is getting that tip just right so it doesn't foul in the PTFE tube.  when that happens, it leads to all sorts of other errors.  I just need to justify buying reels of Prusament that technically I shouldn't need to, given my 20+ rolls of other branded filament lying around!

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

Posted by: @apromain

I joined a forum on Facebook last year to try and get 'help' for my MMU2S struggles - I ended up leaving as I was shouted down for criticising it.  Stepping back a bit, I am a qualified Electro-Mechanical Engineer, 30yrs+ experience, and I am struggling with the damn thing!  When someone on the FB group posted asking whether it was worth it, I posted honestly, with my experiences, stating, as has been mentioned here, that it requires far too much work to make it worthwhile unless you're up for the challenge.  I may as well have been sending death threats to Josef Prusa, with the level ad content of replies I had!  Quite simply, it's not fit for purpose as a plug and play product, and as has been mentioned, is very much a beta product.  I have been running 2 x MK3s' quite happily, and when I purchased the second one, bought the MMU2S.  After 3 or 4 frustrating months, I removed it.  I needed a working printer, and it just wasn't happening.  A few days ago I decided to fit it on and try it again.  I have just had to walk away from the damned thing after a day of playing with it, before I smack it with a sledgehammer.  It's consistently inconsistent.  I have tried different brands of filament, and that seemes to be the key to getting the consistent 'tip' needed, but even then, every so often it just stops and blinks at me.  I follow the help guides for the relevant lights, and it does nothing.  It's like it's challenging me 'hey, Andy, guess what my problem is.....nope, that's not it.....nor that......guess again'.  I've left it for the night now before I lose my rag and smash the damn thing up.  My other non MMU2S MK3S is chugging along brilliantly making money for me, but this one is something else.  I think that's the problem - my first 3D printer was a Creality Ender 3 that I modded like a madman, and it took a lot of work.  Then I bought my Prusa, twice as fast, and worked effortlessly after I had built it.  I think we have that expectation that the MMU2S is going to be the same, but it's far from it.  I hate to criticise Prusa, as they had been helpful to me with other matters, but the MMU2S is just a major disappointment.  I aim to load it up with 5 reels of Prusament, and just see what happens then.  The key for me is getting that tip just right so it doesn't foul in the PTFE tube.  when that happens, it leads to all sorts of other errors.  I just need to justify buying reels of Prusament that technically I shouldn't need to, given my 20+ rolls of other branded filament lying around!

If you want to sell it and recoup some money send me a message. I’d be interested.