MMU3: How well is it working for you?  

RE: MMU3: How well is it working for you?

Mine has been 100% reliable and works really well. I can't remember ever having any issues.

The following 3 items have been game changers for me:

- Filament sharpener......gives the filament a nice rounded tip so it doesn't snag when loading
https://www.printables.com/model/850863-mmu3-tool-tip-sharpener

- Loading fork.....the single most useful tool I have ever used for my setup. Makes loading a breeze
https://www.printables.com/model/829946-mmu-loading-fork

- Filament speed loader......does all the work and loads filament easily from spool, through buffer, all the way to the MMU3
https://www.printables.com/model/1219294-bowden-speed-loader-for-prusa-xl-and-core-one-and

RE: MMU3: How well is it working for you?

If you're printing PLA, it works decently.   Anything over a day in printing is bound to experience something that needs attention.  Trying to add silks to a model almost ensures that.    If I ever get my core upgrade, there's no way I'd ever stick the darn thing on top of the enclosure like Prusa does, but mount it on the side.   While issues are somewhat infrequent, the last thing I want to do is climb over an enclosure to manipulate filament.  The whole thing needs to be redesigned from scratch.  I couldn't believe that they still required tools to open v3 of the MMU. I tossed that and printed an ultimulti and its functional.

Does the Bambu AMS have loading issues?  Is the AMS design a better design mechanically?

RE:

Upgraded mode Core One not long ago to the enclosed MMU3 version. 

The MMU3 unit itself seems fine and works as intended, but the spool holder system is hot garbage and should never have been done the way it has.

The amount of fiddling around to load spools, adjust the spool holder to match spool etc is much more delicate and annoying than it needs to be.

• Having the feed tube be almost under the spool means that you cannot load the spool while it is on its stand
• Having the spool holders be connected in a quarter of a circle next to the machine takes up way too much space
• Having the spool holders be connected makes it hard to see if spools are in their proper slots
• Having the spool holder slots move independently makes them have a lot of play and you often end up having a spool on 3 wheels only so you need to check all 4 wheels when adjusting
• Having the spool holder slots be convex instead of concave in its design makes it easy for the spool to fall off when adjusting or feeding filament

One thing that I am unsure of though, is whether the enclosed chamber part of my core one is now broken/ineffective and if the vents actually do anything now, because there is a big gaping square hole on the backside of the MMU3 enclosure where the PFTE tube between MMU3 and the printhead is. It is something that I’d need to do some testing on.

There are a few gripes with how the MMU3 itself works.

• I wish the selector doesn’t run into one of the sides as hard as it does on startup. It cannot be good for the motor in the longrun. For a few seconds it sounds like back in the day when you didn’t connect the endstop correctly.
• I wish the loading/unloading was done better. It’s currently the loudest part of the print by a longshot because its unloading/loading at full strength and the motor is outside of the enclosure. If “stealth” mode could also make it load/unload slower to make less noise I would be very happy.
• I wish the whole MMU3 part was inside of the MMU3 enclosure. The buttons on it are not needed, since everything can be handled in the display, except for stopping the loading, if you accidentally pressed the wrong loading function. Please add this function to the display Prusa. 
• I wish that on loading filament it will prompt me to choose what filament I put in, instead of having to go into a separate menu afterwards and change filament type. 
• And then I wish that you could select a color as well when you set filament type, just for some added help/insurance that you’ve connected the correct spool to a color in the print menu.

But those gripes aside, the actual printing works and works good and consistent. I haven’t had any failures or misbehaviors in the loading/unloading process so far. And I do love that you can connect which spool corresponds to which color / filament type before you print so you dont need to unload/reload multiple spools to get the correct ordering for your print.
And I think many of those gripes I have can be fixed by simple software/firmware upgrades, luckily

RE: MMU3: How well is it working for you?

It doesn't. I upgraded it and tried to make it work but no, not reliable at all. I'm currently in the process of removing from my MK3S+ and going back to single material. A huge waste of time.

RE:

It's going pretty badly for me so far.

I've played with a few 3D printers so far and built the MK3 from kit and upgraded to MK4S with zero trouble.The MMU3 is a whole other beast. It might be because of my choice of filaments or something else but it has been  nothing but pain.

The MMU3 idler tension was extremely sensitive for me. Too tight and it grinds the filament into a powder at the teeth. Too loose and it can push the filament into the extruder but not retract it. Or vice versa. There seemed to be a sweet spot but it was never stable. Ten changes later, that sweet spot is somewhere else.

The FINDA sensor is finicky as well. There's no filament in it, but in just half an hour of printing it accumulates so much dust that it thinks there's a filament in it when there isn't.

The cascade of failures is also quite problematic. I set the temperature too  high once. The filament started stringing as it was being retracted from the extruder. FINDA thought the filament was still there, and the MMU3 kept retracting. The filament got ground up near the teeth and wouldn't move any more. So the only fix was to tug it out, open the MMU3, and clean it up. On another occasion the teeth were grinding at a filament in place but eventually the filament got pushed out to the extruder. Once in there, it got stuck in the gears and wouldn't move any more.

I can't believe that this is the state of the art. In comparison MK4S without MMU3 has printed hundreds of models for me without once needing an intervention. Also, I've paid about the same for the kit that Bambulabs' AMS would cost, fully assembled. And I've seen this one in action - it's somewhat slower and wastes more filament but I'm yet to see it fail.

RE: MMU3: How well is it working for you?

OK, here's mine: Assembled from kit a few days ago, shortly after the printer. 

BTW, a "difficult" build? The MMU3 less so than the printer but difficult in its own ways. Both would be extremely difficult for non-enthusiast industrial technicians, e.g. the margin to strip some of the threads appears to be negative - you need intuition which screws not to tighten.

And it tried to bite me when I "calibrated" the FINDA sensor. I was faster. Heh.

After that, curiously, it just works (a few hours test prints, several hundred tool changes). No need for iterative adjustments or the like. Maybe the ABS I'm using (as it's the least moisture sensitive) is unproblematic. Fingers crossed.

RE: MMU3: How well is it working for you?

BTW the advertised numbers for wasted filament on the web might be pessimistic if I tweak the settings.

Default purge volume seemed very high - I dialed this down quite a bit, and the size of the wipe tower shrinks drastically. If there is any color mixing (print is running), I can't see it.

For example, the custom marble-rail lego bricks below use 6.4 grams, with 1.85 grams of wipe tower. But I could fill the whole print bed with copies, and the wipe tower would remain unchanged. 

The MMU3 is efficient.

RE:

One observation, not directly MMU related but maybe of interest:

Printing an object from several colors creates boundaries that are necessarily weaker than the same printed in one color. There are some slicer settings e.g. beam interlocking to overcome this, but I didn't find a good automatic solution to my self-imposed "brick challenge" (which turned out quite a bit harder than originally envisioned... just a Lego brick...). Connection to the side walls was nowhere as robust as a single-color print.

Workaround: fix the design, "step joint". This is again robust. But the sidewalls aren't pretty anymore (note, this is ABS for extra challenge. PLA would be easier).
The journey continues...

Another random observation: it seems the overall material throughput has dropped below three grams of ABS per print hour.
MMU turning this into a very cost-efficient hobby 🙂

RE: MMU3: How well is it working for you?

It's pain in the ass. Really waist of time. Only benefit of MMU3 is that I can have prepared 5 colors and maybe it's easier to change the spool. Nothing else. I was able to print two color object only onece in three months I have MMU3.

RE: MMU3: How well is it working for you?

Hello Everyone!

It doesn't work for me. Im not saying that MMU3 itself isn't a great tool, just not for me. I had a good result with PLA and PETG, but in 95% I'm using ABS / ASA.

With ABS and ASA I had a lot of problems with quality on top surfaces, even worse if I use ironing. Never had this problem with single colour printing. I tried playing with settings etc.

I don't  have any complaints because MMU3 works just fine with what was designed for ( PLA / PETG).

I take a risk because I didn't want to buy second 3D printer just for couple products printed in multicolour, so I decided for add on to my Prusa Core ONE. I sold MMU3 and CoreBoxx and invested in printer with different multicolour system. But Core One is still my go to printer. Now Im waiting for INDX 😀 

RE:

Posted by: @veete_ch

It doesn't work for me. ...but in 95% I'm using ABS / ASA. 

I use with ABS and recently ASA. Learnings things the hard way but the MMU does what it's supposed to do.

One hint: I have tried only one brand of ASA so far, but found moisture to be a serious issue. The material came unusable out of the sealed bag, but the filament drier makes a night-and-day difference.

Check whether moisture is an issue. I don't leave it loaded but retract it into the drier after prints.

When bone-dry, my brand of ASA gets fairly brittle and needs to be handled carefully. Manageable, though, just demands a bit more diligence when handling.

One "gotcha": After mistakes, check the filament ends for pulley damage (e.g. unsuccessfully retracting after stuck in the nozzle will damage the filament, causing issues in the next print).

RE: MMU3: How well is it working for you?

I have had my MK3S+ with MMU3 for a couple years now and regret the purchase. My longest successful print was this - just a few layers. 

I hate the original spool design and how much table space they take up. Also, when something goes wrong, it' challenging to recover. When I have to disaassemble and troubleshoot, I invariably bump or loosen something else and the troubles continue. I ended up going back to single color and buying a bambu p1s for multicolor. 

The MMU3 really is the bane of my existence. Somehow I can't just give up on it and am going to try to mess with it again after this.

RE: MMU3: How well is it working for you?

Mine works well. BUT I have never used the Buffer... 
Before I Got my Enclosure, 
I had my printer on a workbench, and I had five spool holders on the shelf, above and behind the printer. 
 
I drilled a 4mm hole through the middle of each spool holder and through the shelf below it, and installed a short piece of 4x3mm PTFE through the shelf. 
then I Put lengths of 4x3PTFE into the back of the MMU3, that were just long enough to form a gentle curve up to the tube through the shelf. 

Like this... (I am not very artistic so this is my best impression of a side view of one filament path, there are actually five filament spool holders and five sets of PTFE)

This setup effectively has unenclosed buffering in mid air, between the long and short PTFE

Note... I started using this setup with My MMU1 many years ago, so the left hand side of my workbench has an almost identical setup with four more filament spool holders, for My MMU1, which is still working . 
When I had the MMU2, I also used this setup... (My MMU3, is one of the first MMU2 to MMU3 upgrades)

Last year, at SMRRF in Manchester England, the chaps on the Prusa stand, were pushed for time and space, and they used the Air Buffer Idea instead of the 'proper' Prusa Buffer...

now that I have an enclosure I have 4 spool holders on the outside of the enclosure, and one on the inside of the enclosure, and I use a similar setup with the PTFE sticking out of the sides of the enclosure... It's a bit ugly, but it works.   

When I am using BVOH, I put that on the fifth spool holder inside the enclosure, where the humidity is lower...

(After a long time using this process... I am going to try rewinding spool holders on my next MMU3)
that's due to arrive Mid December... (I Hope)