Is the MMU2 finally starting to come together?  

Re: Is the MMU2 finally starting to come together?

Since I made changes to the extruder body and started using larger ID PTFE tubes, the only fails I have had have been the unusual ones (filament break in Bowden and top Festo undoing itself).

Other than that printing without problem or intervention.

Peter

Re: Is the MMU2 finally starting to come together?

i had problems on the first day which was just setting the machine up and working out the kinks. i fixed some mechanical defects in the prusa parts. then after 1 hour of fighting with things i started to replace all the spool holders with pmeyers redesign on thingiverse.
on the second day i had 2 layer skips that was my fault because i didn't prep a new spool and just started printing. there was additional fine tuning of slicer settings.

since then i've had 100s of hours of prints that were successful in having no skips or jams.

there is a lot to be taken from that as i have a large table setup and i'm not attempting to cram into a IKEA table with PTFE routing, and i'm using a standardized PLA brand, hatchbox pla for everything and do not plan to really mix PLA from different companies.

i have not run PETG or BOVH yet.

in this time i have also made modifications to my MK3 MMU2 machine to try and address issues with my MK3 machine and in the process i broke a few parts that i needed to reprint on another 3d printer (MK2S) in PETG.

Re: Is the MMU2 finally starting to come together?

Since I made changes to the extruder body and started using larger ID PTFE tubes, the only fails I have had have been the unusual ones (filament break in Bowden and top Festo undoing itself).

Other than that printing without problem or intervention.

Peter

What size ID PTFE tubes did you switch to? I assume you replaced the tube between the extuder and the MMU2, the little ones between the selector and the bontechs and maybe also the ones running to the filament trays?

Re: Is the MMU2 finally starting to come together?

What size ID PTFE tubes did you switch to? I assume you replaced the tube between the extuder and the MMU2, the little ones between the selector and the bontechs and maybe also the ones running to the filament trays?

I replaced the filament feed and Bowden with 2.5mm ID PTFE. I also removed the lower Festo and gripped the Bowden with an amended extruder body, so the Bowden is a little longer and is a tight push fit into the extruder body, but the filament path has no ledges to cause problems. I made both changes at the same time.

Peter

Re: Is the MMU2 finally starting to come together?

I replaced the filament feed and Bowden with 2.5mm ID PTFE. I also removed the lower Festo and gripped the Bowden with an amended extruder body, so the Bowden is a little longer and is a tight push fit into the extruder body, but the filament path has no ledges to cause problems. I made both changes at the same time.

Peter

This sounds like it could solve 99.8% of my problems. Where do you get 2.5mm PFTE?

The thing that saddens me most about the MMU is that it's not integrated with the MK3. It can't use the display or menu, it's doing silly LED blinking. The MK3 doesn't even know it's there if it had a boot failure mode. Also that the MMU reboots when Octoprint connects...

And things like temperature changes doesn't seem to be properly supported. (That's a slic3r PE problem though.)

Re: Is the MMU2 finally starting to come together?

I'm printing prusament blue and silver with bvoh at the moment. Blue works fine, with silver I get a lot of stringing (sometimes not from the beginning but after several hours of printing it starts stringing midprint), bvoh works 75% of the time.

Sometimes when I start the print the printer does "weird" things at the start and triggers crash detection. After restarting the print or the printer it usually works.

You can see that a lot of people doing “updates” to the system. There is even a custom firmware out which a lot of people are using.

Slic3ers pruge into infill is nice. But I need to set ramming temperature to get rid of stringing.

My MK3 printed without the MMU2 flawlessly for about a year.

But for 300€ you can have a lot of fun tinkering with the MMU2 unit so I think it is worth the money. But it is still a looooooong way to go until it reaches MK3 reliability (if it will ever).

Re: Is the MMU2 finally starting to come together?

This sounds like it could solve 99.8% of my problems. Where do you get 2.5mm PFTE?

eBay. Sorry, can't be more specific as I don't know your location.

Peter

Re: Is the MMU2 finally starting to come together?

This sounds like it could solve 99.8% of my problems. Where do you get 2.5mm PFTE?

eBay. Sorry, can't be more specific as I don't know your location.

Peter

Just to confirm, 4mm OD 2.5mm ID? This seems like it'll solve a lot of issues, so I'd like to look into this.

Did you chamfer the inside to 4mm, or just leave it as 2.5mm throughout?

Re: Is the MMU2 finally starting to come together?

This sounds like it could solve 99.8% of my problems. Where do you get 2.5mm PFTE?

eBay. Sorry, can't be more specific as I don't know your location.

Peter

Stockholm. Basically this stuff then? https://www.ebay.de/itm/Ptfe-Teflon-Rohrleitung-Rohr-4mm-Od-X-2-5-mm-Id-pro-Meter/131229025205?hash=item1e8ddc03b5:g:8koAAOxydB1Sfxo-:rk:4:pf:0 (I am not affiliated)
https://www.aliexpress.com/item/2-5x4mm-PTFE-F4-Teflon-Tubing-Pipe-ID2-5mm-OD4mm-Brand-New-Wire-Protection-Free-Shipping/32756143565.html

Re: Is the MMU2 finally starting to come together?

My MK3 printed without the MMU2 flawlessly for about a year.

But for 300€ you can have a lot of fun tinkering with the MMU2 unit so I think it is worth the money. But it is still a looooooong way to go until it reaches MK3 reliability (if it will ever).

Thanks for putting that nicer than I did. It's not just that it isn;t working, but there's no assurance they are working on it, that the problems matter, or even anyone to tell you if how it behaves is by design or a specific problem with your unit.

If not for the user community it would be useless. A few well meaning folks at Prusa have been great, but nothing has led to actionable solutions.

Re: Is the MMU2 finally starting to come together?

Just to confirm, 4mm OD 2.5mm ID? This seems like it'll solve a lot of issues, so I'd like to look into this.

Did you chamfer the inside to 4mm, or just leave it as 2.5mm throughout?

Yes, 4mm x 2.5mm. I purchased 5 metres of transparent so that I could see the movement. The upper end is transparent.

I have attached my extruder body fix which removes the optical sensor (which is just not needed at all) and allows the Bowden to be a push fit into the body. I have more than 150 hours of print without the PTFE coming out, so I think it works OK.

Basically this stuff then? https://www.ebay.de/itm/Ptfe-Teflon-Rohrleitung-Rohr-4mm-Od-X-2-5-mm-Id-pro-Meter/131229025205?hash=item1e8ddc03b5:g:8koAAOxydB1Sfxo-:rk:4:pf:0

That's it.

Peter

Re: Is the MMU2 finally starting to come together?

there's no assurance they are working on it, that the problems matter

The original designer of MMU (both 1 and 2) is working on it. And it does matter to him. Only problem is that he gets very little support from others.

There will be something new, but it's won't be for a while.

Peter

Re: Is the MMU2 finally starting to come together?

My MK3 printed without the MMU2 flawlessly for about a year.

But for 300€ you can have a lot of fun tinkering with the MMU2 unit so I think it is worth the money. But it is still a looooooong way to go until it reaches MK3 reliability (if it will ever).

Thanks for putting that nicer than I did. It's not just that it isn;t working, but there's no assurance they are working on it, that the problems matter, or even anyone to tell you if how it behaves is by design or a specific problem with your unit.

If not for the user community it would be useless. A few well meaning folks at Prusa have been great, but nothing has led to actionable solutions.

I just had to cancel a print after 17 hours (24 h total) because the mmu motor for the idler body suddenly stopped working. Restarting the printer and it worked again.
Very frustrating 🙁

Re: Is the MMU2 finally starting to come together?

hey peter.122.

I am using stock everything. and right now a test print is on tool change 1925 out of 3975. it does work.

Re: Is the MMU2 finally starting to come together?

Same thing for me. Everything stock (except the filament holders). Adjusted only the temp for the filament. Here is my most recent 27 hours print without any user intervention:

Re: Is the MMU2 finally starting to come together?

I sure would give anything to have someone tell me what's wrong with my machine.

I *has* done some great, many-hundred-changes prints.

But it's done 100's of booting up, feeding the wrong filament, Z-height suddenly 180 um off, etc. It just works one time in twenty.

It's not that it CAN'T work. It's that it doesn't work. Would you drive a car where the seatbelt holds just fine 20% of the time?

Re: Is the MMU2 finally starting to come together?

I sure would give anything to have someone tell me what's wrong with my machine.

I *has* done some great, many-hundred-changes prints.

But it's done 100's of booting up, feeding the wrong filament, Z-height suddenly 180 um off, etc. It just works one time in twenty.

It's not that it CAN'T work. It's that it doesn't work. Would you drive a car where the seatbelt holds just fine 20% of the time?

Part of the problem is that printing multimaterial has a lot more variables than a single material, with the result being that there's exponentially more combinations of things which might lead to a problem.

We're still at early stages and don't yet understand what actually matters and what doesn't. We know that if everything is just right it can work, but unexpected things (like using a certain brand of premium nozzle) will lead to failure.

It's cold comfort if your machine isn't working for mysterious reasons. But I'm optimistic because I can see that the community is gaining experience quickly and better understanding where the envelope of success is.

Re: Is the MMU2 finally starting to come together?

i am almost to the point of trying a 2nd material. if my 4000 tool change finishes throwing in a 2nd material is next on my list (after printing a nice fast 2 color print

Re: Is the MMU2 finally starting to come together?

The original designer of MMU (both 1 and 2) is working on it. And it does matter to him. Only problem is that he gets very little support from others.

Who is the original designer and how can I help him?