Extremely disappointed with MMU2S
I ordered the i3 MK3 last fall and have been enjoying it immensely. I figured I'd take it to the next level and ordered the MMU2 near the end of last year, maybe November and got it about a month ago. I finally got around to the major task of upgrading to the i3 MK3S and adding the MMU2S. Painful but kudos to the effort in the instructions that I was able to make it through.
Then to learn of this massive buffer required. The table real-estate I was not aware of, don't we all want a compact printer with some spool orientation maybe a wall or shelf? Yes, I've been through google and Thingiverse and looking at options. I have yet to get through a print without MMU failed to load or some attention required, I'm trying one of the sample multi color models downloaded from the Prusa site with about a 7 hour build time. I haven't gotten it past one hour yet.
After being baffled with the buffer initially I tried just setting the spools on the MMU2 included spool holders off to the side. It seemed like it was going to work and despite the mess there were just too many other things going on such as extruder not loading filament or MMU not loading, goodness, who knows but I think I got things tweaks to the right tensions. I also think there is a design flaw in that when the MMU fails to load the nozzle cools and then when you get that resolved it tries to push filament through the extruder that's not at the required temp.
Last night I tried the buffer again putting it behind the printer resting against the wall and the 5 spools on a shelf above the printer. I actually thought finally I got it to where I could complete a print, I monitored it through all 5 colors and it continued on printing. I went to bed to wake up hoping to finally see a completed print, nope, about one hour in it had failed to load and would not get filament through the extruder. The MMU was pushing/pulling it just fine.
I heated the extruder to 255 and pushed the metal pin gadget that came with the MMU kit down the hole after of course removing the ptfe and opening the extruder so the bontech gears allowed the rod to pass. Still some issues with getting filament in but after removing and wasting yet more filament and cutting the angled end again it finally printed. I have since gone back to single extruder print setup and just completed the first print since the rebuild.
I regret this purchase and mod, I just want my trusty prusa back. I know I can revert it but won't, I will probably figure out something with the buffer and my setup but this has really changed the printing experience for the worse, so far. It takes time, I know, I'll keep at it. I also enjoyed taking the printer in my RV on trips and printing even during travels in my motorhome, that may be a thing of the past but I think with a shorter ptfe in extruder 1 and using single filament mode I can get back to portability.
I guess now I'll spend time looking at buffer options, printing, architecting ptfe holders for my shelving setup, etc.
If you're looking at adding a MMU2 be sure to really think through why as I'm not sure the good outweighs the bad. The buffer concept needs a complete rethink, some retractable spool design sure would be nice.
I hope others are more successful but this has been a royal PITA so far and I really miss my printing addiction with the Prusa i3 MK3.
Neal C
Richmond, VA
RE: Extremely disappointed with MMU2S
Your post makes me want to commiserate and voice my own complaints, but I think I've done that enough already and need to tone it down.
I'll leave it that I agree with everything you've said and have some additional complaints on top of if. I suppose there is solace in knowing we aren't alone, but this is a really disappointing experience.
RE: Extremely disappointed with MMU2S
I don't like original Prusa buffer solution and even v2 but nowadays there are already tons of different solutions made by community memebers. Wall mounted, separated stands, in-box solutions ...
You can use this as a starting point https://www.thingiverse.com/thing:3338467
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
RE: Extremely disappointed with MMU2S
If you're looking at adding a MMU2 be sure to really think through why as I'm not sure the good outweighs the bad. The buffer concept needs a complete rethink, some retractable spool design sure would be nice.
I hope others are more successful but this has been a royal PITA so far and I really miss my printing addiction with the Prusa i3 MK3.
@nealc, I sympathize with you, I've had more than my share of problems with the MMU2 and then the S version, as well. Prusa should include a warning on the box: DO NOT attempt this upgrade unless you have a) the patience of a sloth, b) weeks-worth of spare time to spend on research, tweaking and printer baby-sitting and c) no pressing need to get anything printed right away.
Many thanks to @nikolai-r for mentioning the rewinding spool holder, I'm definitely going to make one.
Fair farren
RE: Extremely disappointed with MMU2S
I really sympathize. After following the excellent instructions i tried my first print. It was downhill since then. FINDA false readings, more time going though loading failures than actual printing and more PITA that its worth. I bought it when i read Joseph blog about the months of testing and the great results. I really want it to work since it the only option i can think about soluble supports. But i dont know. My personal advice is to buy this thing only if you like gambling, or it comes in an assembled pretested version.
100 % agree
To tell it with gnats words: I have to tone down a bit too. Otherwise I´d just rip the thing off and throw it in the trashcan. I´d even print a rewinding spool holder but the problem is the prusa doesn´t print anything right now. So I either wait for PRUSA to come with some solutions or I´d downgrade to MK3.
RE: Extremely disappointed with MMU2S
@thomas-m83 disconnect the MMU (PTFE and power) and then you should be able to print as a plain MK3S. I had to disable the filament sensor too.
That should hopefully either let you print or it at least takes the MMU out of the equation if there are other issues that need to be fixed. Other than the filament sensor and the warping housing mine has been doing great like that.
Finishing a second rewind spool today, then I'll reprint the filament door to see if that helps with the filament sensor issues. After that I'll try the MMU again and if it still doesn't work I'll tear the extruder apart again this weekend for the Butterworth mod.
RE: Extremely disappointed with MMU2S
I don’t understand why people (and Prusa) are overcomplicating the spool holder solution. Everything you need before the filament gets into the first long MMU2 PTFE is a second (smaller) PTFE. That’s it. For example, something like this: https://www.thingiverse.com/thing:3094325
If you have the spool holders in a container it’s even easier. Just screw the Festos on to the container. And obviously make sure that the spool holder itself doesn’t create much friction.
That’s it. Works for me for months now with no problems at all.
RE: Extremely disappointed with MMU2S
I don’t understand why people (and Prusa) are overcomplicating the spool holder solution. Everything you need before the filament gets into the first long MMU2 PTFE is a second (smaller) PTFE. That’s it. For example, something like this: https://www.thingiverse.com/thing:3094325
It's an issue because the tool chain ejection is the source of many MMU issues and is why Prusa finally added the buffer as many users had already figured out on their own. The reason it is "over complicated" is that not all of our work spaces are equal. I personally don't have the space for the way Prusa wants things laid out.
While your solution looks simple and I believe could help, that still won't work in my situation as the only place for ejected filament to go would be into the path of the printer or another spool.
RE: Extremely disappointed with MMU2S
I have found 2 things that have been invaluable for diagnosis. First, add an led to the Ir sensor so a camera can see it light up. Second, set up a camera to record the print.
I used a web cam and recorded to my computer. After a failure I could replay the video when it stopped printing and figure out where the error occurred.
knowing where the tip of the filament is when it acts up is half the battle.
RE: Extremely disappointed with MMU2S
I can only agree with OPs oppinion. I have seen all the issues you noticed myself and am too very disappointed in the product. I too wasn't able to get one single multi material print to work. In my oppinion the product is simply not yet ready and just feels lika a payed public alpha... I really hope they manage to make improvements in the design and the firmware in order to improve reliability.
RE: Extremely disappointed with MMU2S
Just to give you guys the other side. I'm glad PR released MMU2 kit. It's an improvement to MMU1 and it's at unbeatable price.
The price tag for Palette2 Plus is way too high for me. But with MMU2 I'm printing real multi material already for half a year and got really nice looking printed objects. The features like filament run-out are still working fine and start/end procedure is even improved because filament is always unloaded.
Yes, it's not plug and print experience. There are a lot of things which can and will go wrong but at the end of the day I have a very high success rate on prints. The shelf full of colorful prints is making me happy.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
RE: Extremely disappointed with MMU2S
Another disappointed MMU2S user here. Since fitting it that Mk3 sits mostly idle. I do not have the time or the patience to babysit ten hour prints because that is the only way I can get a successful print out of it. I keep meaning to take it off and regain my second printer, but stupidly I still hope that Prusa will come up with a fix. A forlorn hope I fear.
RE: Extremely disappointed with MMU2S
I've only done my first print, and I had to intervene a lot of times with load/unload issues. I'm learning... but I used the Autorewind spool systems, and they worked a charm right off the bat.
After finding that I had the springs on the mmu2s way too tight (I ground out the filament that was supposed to be loading), it got started.. but my main persistent issue was stringing I think after ramming/or whatever its called... getting stuck enough in the FINDA spot to raise the ball bearing enough to trigger the FINDA -- therefore a "not unloaded" state. I raised the FINDA a tiny bit higher and it helped. But then there was a proper blob that got stuck. Can't help that. That's filament.
I've also seen a mod somewhere that uses a magnet to properly pull the FINDA ball down when not engaged. This would probably help a lot because the FINDA isn't totally vertical when the MMU2s is hung from the i3 mk3s frame - so gravity isn't at max.
RE: Extremely disappointed with MMU2S
I'm printing real multi material already for half a year and got really nice looking printed objects.
But only thanks to your very good temperature script 😊
RE: Extremely disappointed with MMU2S
Considering how reliable my MK3 has been since I received it (Jan 2018--the only reason it ever went down during the 100 days of print time I've had with it was because of a bad Y-axis bearing) the MMU2 has been a bit of a disappointment for me. I wasn't expecting it to be nearly as convenient as the MK3 itself, but I was expecting it to be far less finicky than it's been. The prints that were successful look good--really good, honestly--but I've definitely sunk more time into tinkering than I have into printing.
Now that the fiddly length-based calibration is a thing of the past with the MMU2S, my main pain point continues to be the PTFE fittings in the back of the selector. I have a handful of successful prints that look very nice, but the way the tubes fit into the back has always felt a bit dodgy to me and even after a lot of fiddling I've never managed to quite get that quite right. My first attempt after doing the MK3S/MMU2S upgrade (a 2-color Benchy) actually went pretty well up to about the 15mm mark before the second filament slot (which had, until that point, been able to smoothly load filament) started binding to the point where the MMU2S gears were grinding the filament despite the idler actually being a bit too loose. Yikes. My best guess is that the tube was slightly loose and shifted slightly with every retraction, but I'm not sure.
There is an [url= https://www.thingiverse.com/thing:3233579 ]alternative to the stock PTFE holder[/url] on Thingiverse (courtesy of [url= https://www.thingiverse.com/vertigo235/about ]vertigo235[/url]) that I'm going to try. From the look of it, it seems as though it should hold the tubes firmly in place without pinching them, and it would make it easier to disconnect the tubes if necessary. If you're at your wits end it might be worth a shot, especially if you already have some M10 fittings lying around.
I'm going to print the part for that tonight. Amazon willing, the fittings that I ordered should be arriving tomorrow. Fingers crossed!
RE: Extremely disappointed with MMU2S
I guess now I'll spend time looking at buffer options, printing, architecting ptfe holders for my shelving setup, etc.
Hi,
Sorry to hear about your problems. The upgrade to MMU2S actually made my printer reliable. One possible cause for stop in the extruder could be some foreign material blocking the plastics in which case a cold pull (preferably using nylon) is recommended.
Anyway, here's an alternative filament buffer:
https://www.thingiverse.com/thing:3634268
Good luck!
RE: Extremely disappointed with MMU2S
Just to give you guys the other side. I'm glad PR released MMU2 kit. It's an improvement to MMU1 and it's at unbeatable price.
The price tag for Palette2 Plus is way too high for me. But with MMU2 I'm printing real multi material already for half a year and got really nice looking printed objects. The features like filament run-out are still working fine and start/end procedure is even improved because filament is always unloaded.
Yes, it's not plug and print experience. There are a lot of things which can and will go wrong but at the end of the day I have a very high success rate on prints. The shelf full of colorful prints is making me happy.
Yeah I know it is leaps and bounds ahead of the original and it's from people like you, Joan, and a few others that give us hope that once we get it going it will be a great tool. I think some of the frustration stems from them promoting this as a ready to go tool and that the S upgrades were touted as improving/solving many of these issues. Compare the MMU to the printer itself, people certainly have some trouble with initial prints but they are almost always resolved quickly and then operation is easy. Not so with the MMU.
I looked at the Palette, but went with the MMU based on Prusa's rep for their printers (and thus made the mistake of not reading the MMU forum...). While waiting on my MMU (5 months) there were multiple times that I considered canceling and ordering the Palette, but every time I looked at it I found that it appears to have just as many issues and the support is MUCH worse.
I guess in all their marketing promoting the MMU a little honesty would have been nice to make it clear that it isn't as plug and play as the printer itself and is more for the person that has the time to fiddle with things. It also feels like rather to continue working on it and improving the usability, they put all/most of their eggs in the SL1 basket. Hopefully with the SL1 finally coming to market they'll put some effort into making the MMU more reliable.
I'm still trying with mine, but after a month of ignoring my family more than usual all I have to show for my effort and frustration are a couple of spool holders, a couple of extruder housings, a Benchy, and a couple handfuls of "Life Z" and test cube prints without any being multi-color and the Benchy being the only one utilizing the MMU. Keeping with it's personality, when I finally reconnected it last night and tried to load it up filament stuck in the selector in a manner that I'm going to have to disassemble the thing to remove.
On the upside, I have almost burned through a roll of filament that I otherwise had no idea what I was going to do with (needed it for like 75g)...
RE: Extremely disappointed with MMU2S
There is an [url= https://www.thingiverse.com/thing:3233579 ]alternative to the stock PTFE holder[/url] on Thingiverse (courtesy of [url= https://www.thingiverse.com/vertigo235/about ]vertigo235[/url]) that I'm going to try. From the look of it, it seems as though it should hold the tubes firmly in place without pinching them, and it would make it easier to disconnect the tubes if necessary. If you're at your wits end it might be worth a shot, especially if you already have some M10 fittings lying around.
Oh I like the look of that mod. As I have limited space being able to pull the tubes and reinsert them when dealing with a jam is a PITA. That would make things significantly easier. I'm going to have to wait until there is at least a hint of light at the end of the tunnel though before I spend any more money on it...
RE: Extremely disappointed with MMU2S
Oh I like the look of that mod. As I have limited space being able to pull the tubes and reinsert them when dealing with a jam is a PITA. That would make things significantly easier. I'm going to have to wait until there is at least a hint of light at the end of the tunnel though before I spend any more money on it...
The mod's design makes a lot more sense to me than the normal design (which made me go "wait, what?!" from day one). I'll try to remember to post an update after I get everything installed.