[Geschlossen] MK2/S upgrade to MMU --> disastrous?  

Re: MK2/S upgrade to MMU --> disastrous?

Well don't expect official support here, but you'll find loads of threads (some of which are helpful) by other frustrated users. Sorry, but I'm afraid you'll have to do a lot of reading.
It seems to me your filament snags on the metal tube inlet in the multiplexer. You'll probably hear a cracking noise right after the filament enters the Festo couplers. The way to fix this: Make sure you have no burrs in the printed part channels, if you do clean them out with a bit of sharpened filament (or very carefully with a needle). Put in the metal tubes. Loosely attach each Festo, then put a length of filament all the way through to center the whole thing. With the filament still in, fix the Festo. The filament should move freely without much resistance. Remove it, then rinse and repeat for the other three channels.

When loading, it helps to position the print head somewhere in the center of X, and at about 50-60mm Z. It doesn't matter how long you wait before you press the button, I usually hit it as soon as I fell the gears pull. Also before loading it is crucial to cut the filament end at about 45°, otherwise the corners are likely to grind against the metal tube edge. Even with all those, sometimes loading fails (maybe one in 10 for me). Check the priming line(s) carefully before starting prints.

Re: MK2/S upgrade to MMU --> disastrous?

Remove the Y splitter from the hotend, load filament and then go in settings and manually move the extruder. Check if the filament comes out the other side of the Y splitter.
If that is the case, install the Y splitter with 1cm of filament sticking out back on the hotend, thereby sliding the filament in the plastic tube that goes in the hotend and try printing.

If it doesn't come out, check where/why it blocks.

If the above works try unloading the filament after the print and loading it again, in the same extruder. See if it works this time.

Re: MK2/S upgrade to MMU --> disastrous?

If it is stuck in the Y splitter, the easiest is to just remove the coupler from the top and look if everything is clear on the inside and remove any obstacles.

Re: MK2/S upgrade to MMU --> disastrous?

Another thing: how is the tension of the bolts at the extruder motors? It should not be too tight, but if it is not tight enough it can't push hard enough and you'll get skipping. Check that too

Re: MK2/S upgrade to MMU --> disastrous?

https://shop.prusa3d.com/forum/original-prusa-i3-mk2-multi-material-f26/monoplexer-and-multiplexer-redesigns-no-metal-part-t12801.html

Y-splitter is where all my problems were as well.

I redesigned the part for your convenience, although at this point, having a mod around to sticky the topic would be nice.

Re: MK2/S upgrade to MMU --> disastrous?

Hi Nils, Joris, Seth,

first of all thanks for all your quick feedback - that's very very nice.
What has happened between yesterday and now.
a) I did figure out how to contact the official support and posted the same question. Will see what their answers will be
b) I removed the splitter and everything connected (PTFE, metal) and checked the PTFE of the hotend first. During assembly I ran into the same issues as most other users (tube too long) and when I tried to cut it short, I think I made a mess. Last night I figured out that I had a replacement tube in my set and after managing to remove the PTFE tube out of the hotend, I inserted the new one (with the proper cone on one side that has possibly a smoother cone than the original one) and managed to assemble it. First improvement that I noticed: The filament that goes through the splitter manages to enter the PTFE tube of the hotend - at least in 2 out of 4 cases without any resistance, and a bit of resistance in the other 2. Now I will try to work on that, although up to now I have no clue how I could remove any "shoulder" that is inside this 4-1 channel of the splitter (which to my understanding is the main problem right now)
c) I checked the idler screws and tightened them a bit - but you are right when saying that too tight is not good either --> will have to work with that.
d) I am still wondering about the position and the resistance of the 4 filament feeders. Regarding the position: At the moment they are on the same level as my printer - I was planning to put them on a higher or lower position - but so far I did not find a good one yet. Regarding the resistance of the feed: I would have expected the filament roll to move much easier - considering the fact that they are running on 4 ball bearings each. That is not the case and I am still to figure out how to lower the pull resistance - as I believe that this adds to the stress of the filament feeding process.
d) I managed to get one filament fed into the hot end and started a print - the result was very very bad, as it seemed that the feeding process was not smooth. It resembled a "hick up" and sometimes there was no filament and the next time it came back - very strange.

That's it for now. In case you are managing to follow/comment my thread, I'd very much appreciate that.

BR, Harald

P.S When inserting the PTFE tubes into the Festos, it made some kind of "click". Removing the tubes from the Festos seems to be impossible. Is there any trick?

Re: MK2/S upgrade to MMU --> disastrous?

When using the original filament holders I put them on top of a box, behind the printer, at approx 20cm from my desk. I also think they aren't smooth enough, especially when your spool is running low on filament.

Plenty of spool holders to be found on thingiverse, and that's what I ended up doing.

Re: MK2/S upgrade to MMU --> disastrous?

https://shop.prusa3d.com/forum/original-prusa-i3-mk2-multi-material-f26/monoplexer-and-multiplexer-redesigns-no-metal-part-t12801.html

Y-splitter is where all my problems were as well.

I redesigned the part for your convenience, although at this point, having a mod around to sticky the topic would be nice.

A mod making your topic sticky would equal to Prusa admitting that you have a better solution than they do.
Not gonna happen I am afraid.

Re: MK2/S upgrade to MMU --> disastrous?

When using the original filament holders I put them on top of a box, behind the printer, at approx 20cm from my desk. I also think they aren't smooth enough, especially when your spool is running low on filament.

Plenty of spool holders to be found on thingiverse, and that's what I ended up doing.

IMG_9518.JPG

Awesome Joris, Will do the same! Would you mind posting your thingiverse model(s). While I found the bar for holding the bearings, I haven't come across the lower connection bars.

Thanks a lot!

Found it - guess it's something similar to this here - :
https://www.thingiverse.com/thing:2521463

Re: MK2/S upgrade to MMU --> disastrous?

This is the one I used:

https://www.thingiverse.com/thing:2451368

Re: MK2/S upgrade to MMU --> disastrous?

No trick with the Festos. Push the blue ring in, push PTFE further in if possible, then pull. If it's stuck use more force, do not wobble. Note that these couplers are not meant to last forever, every time you release one it might break (there are little metal teeth inside which can break off). Also it bites into the tube, so try not to remove it too often - at some point it will fail to connect properly.
In hydraulics where these come from I would say maybe 20-30x before they're useless, 3-10x if they need to be air- or watertight. For our purpose they can last much longer, but there's a small risk of breakage each time.

Re: MK2/S upgrade to MMU --> disastrous?

...and this is my spool holder:
https://www.thingiverse.com/make:411118

I like the design, very space-efficient and it keeps the filament untangled. I've since replaced the 1.85mm PTFE tubes with 3mm to remove a friction and make loading easier. You can remove them altogether but on one occasion it got messy for me when filament got pushed back and unwound the spool too much in the holder.

Re: MK2/S upgrade to MMU --> disastrous?

P.S When inserting the PTFE tubes into the Festos, it made some kind of "click". Removing the tubes from the Festos seems to be impossible. Is there any trick?

Push the blue tab into the fitting and then pull the PTFE tube out, it requires a little force, but shouldn't be too difficult. Just make sure the blue tab is depressed all the way.

Re: MK2/S upgrade to MMU --> disastrous?

https://shop.prusa3d.com/forum/original-prusa-i3-mk2-multi-material-f26/monoplexer-and-multiplexer-redesigns-no-metal-part-t12801.html

Y-splitter is where all my problems were as well.

I redesigned the part for your convenience, although at this point, having a mod around to sticky the topic would be nice.

A mod making your topic sticky would equal to Prusa admitting that you have a better solution than they do.
Not gonna happen I am afraid.

Prusa is based in the Czech Republic. I'm not even sure the English forum mods are associated with the company Prusa other than to moderate these forums.

I'm going to PM Jakub and see if I can get anywhere with it, I feel like if the mods were paid positions, they would be more active.

Re: MK2/S upgrade to MMU --> disastrous?

Prusa is based in the Czech Republic. I'm not even sure the English forum mods are associated with the company Prusa other than to moderate these forums.

It's been a while since I posted here (lack of PR support for the MMU). You will note that I am a "moderator" here; there are currently 4 moderators, of which only one is reasonably active (JeffJordan).

Moderators have been chosen as "knowledgeable" and active forum members willing to help (basically to do the stuff nobody from PR wants to do); their powers are extremely limited and we are unable to make topics sticky or "hard delete" posts. We can move topics/posts, soft-delete spam and warn/ban users, as well as edit posts which for example contain bad language.

Moderators are unpaid volunteers who give up their time to try to assist others. There are no perks for us and neither is there any direct hotline to PR (although knowing how to contact certain staff members has helped in the past).

Only admins (PR staff) can make topics sticky and, since I have been posting, not one single user-created topic has ever been made sticky - although there are a few which would merit being sticky.

Now I am returning to hibernation until such time as PR properly support the MMU and publicly address all the problems that have been raised by unfortunate users.

Peter

Re: MK2/S upgrade to MMU --> disastrous?

Good to know you're still around. Thanks for the explanation.

Re: MK2/S upgrade to MMU --> disastrous?

Now I am returning to hibernation until such time as PR properly support the MMU and publicly address all the problems that have been raised by unfortunate users.

Peter

Glad to see again the slovenian chicken 🙂

Re: MK2/S upgrade to MMU --> disastrous?

Prusa is based in the Czech Republic. I'm not even sure the English forum mods are associated with the company Prusa other than to moderate these forums.

It's been a while since I posted here (lack of PR support for the MMU). You will note that I am a "moderator" here; there are currently 4 moderators, of which only one is reasonably active (JeffJordan).

Moderators have been chosen as "knowledgeable" and active forum members willing to help (basically to do the stuff nobody from PR wants to do); their powers are extremely limited and we are unable to make topics sticky or "hard delete" posts. We can move topics/posts, soft-delete spam and warn/ban users, as well as edit posts which for example contain bad language.

Moderators are unpaid volunteers who give up their time to try to assist others. There are no perks for us and neither is there any direct hotline to PR (although knowing how to contact certain staff members has helped in the past).

Only admins (PR staff) can make topics sticky and, since I have been posting, not one single user-created topic has ever been made sticky - although there are a few which would merit being sticky.

Now I am returning to hibernation until such time as PR properly support the MMU and publicly address all the problems that have been raised by unfortunate users.

Peter

That's pretty much what I figured lol.

Do you have the ability to contact admins at all? Could you possibly PM me some info on how to get in contact with those certain staff members you mentioned?

Keep in mind I'm on the English forums for a reason haha

Re: MK2/S upgrade to MMU --> disastrous?

Now I am returning to hibernation until such time as PR properly support the MMU and publicly address all the problems that have been raised by unfortunate users.

Good to know Peter

Let’s make some common pressure on Prusa and let them come out of their hiding and help all their unsatiesfied customers with MMU - i’m still waiting to see some kind of report about the issues, a plan from them of how they have decided to help all their customers, and last how we will have new parts or some kind of refund.