Extremely disappointed with MMU2S  

RE: Extremely disappointed with MMU2S

Posted by: Spectere

Posted by: gnat

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.

Yeah I assembled the buffer first which has bolts hold the tubes in place so when I got to that part on the MMU I had the same reaction as you. That mod appears to give the best of both worlds where you know the tubes aren't going to shift and cause problems, but they are still easy to remove for dealing with selector issues. There is no doubt I'll make that mod, I just want to see one successful (even if a bit of hand holding is required) print before I print any more parts that I will have no use for if I end up just giving up.

RE: Extremely disappointed with MMU2S

Posted by: Flaviu

Posted by: nikolai.r

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 😊 

And only because of the great community helping out and working together. Many community solutions went into the main hardware/software brunch. This is how OpenSource should work! 

RE: Extremely disappointed with MMU2S

Posted by: gnat

 

them promoting this as a ready to go tool

Where does it say that?

RE: Extremely disappointed with MMU2S

Posted by: Flaviu

Posted by: gnat

 

them promoting this as a ready to go tool

Where does it say that?

As they do not state that it is for advanced users or mention that it can be an involved setup/tuning process the implication is that the product is ready to be used by most/all users. In fact the S upgrade announcement said that it fixed many issues and made it more reliable (seems like we are still seeing as many complaints though). 

I'm not mad at them about that. No business is going to try to scare customers off. It's my fault that I made assumptions and didn't read this forum first. 

RE: Extremely disappointed with MMU2S

Alight I made two successful two-color prints yesterday. Today nothing works anymore, filament gets instantly unloaded again.

My suggestions and hints to anyone who wants to play with this :

1. best bet is you get two printers, one you use to print and one you use to play

2. make sure you are ready to waste much time and filament for multicolor prints

3. keep the gummy bears, don´t eat them while assembling, you will need them to calm down once you want to print just ANYTHING no matter if single or multicolor once you installed the MMU2S

I know I am complaining too much these days probably because I expected something different due to the fact that I had a realiable 3D printer before MMU2S.

I am not going to suggest anything further, that is smart aleck crap. I just see, that many people have serious problems with this thing and that tells me there are a "few" things that need improvement. I´d even redesign and reprint some parts but hey I can´t print anymore 🙁

RE: Extremely disappointed with MMU2S

I finally got a successful 2 color print!

It's not flawless and I did have to help one filament change, but I finally got a print!

There are 3 things that I changed since my last attempt:

• Switched to auto rewind spools.
• Used a mod for the extruder idler door that added a bit to the tab that trips the IR sensor and then filed it down for more consistent sensor readings. It's also looser than the original which allows filament to move through the gears easier. 
• Changed a setting for one of the retraction speed options to make it move faster when changing tools. 

I forget the name of that last setting, but I'll post it later when I pull out my laptop. 

Now I'll print off 3 more auto rewind spools (with dual color clutches!) And then give a 5 color Benchy a try. Hopefully this isn't just a fluke...

RE: Extremely disappointed with MMU2S

Which autorewind holders do you print? I am just not too keen on printing 5x >40h objects once I got the printer working again.

I am currently modeling my own holders, reduced to the minimum required items and using the existing bearings. Will need new 8mm axis though, cause the ones that cam with the MMU are just too short but I got enough 8mm material around here.

RE: Extremely disappointed with MMU2S

I used https://www.thingiverse.com/thing:3338467 and I only ran 2 off so far. Now that I have a 2 color print I'll run off 3 more (dual color for the parts that make up the dial). The only hardware you need for an initial pair is the 4 bearings from one of the MMU's holders (I actually had other bearings on hand so I didn't use the ones that came with the MMU).

My tips:

• Forget the little arm thing.
• Use the short PTFE tubes from the buffer for the back of the MMU instead of the long ones.
• Have your filament go over the top of the spool and head to the MMU from underneath the spool.
• Remove the seals from the bearings and clean them good so they roll super smooth.
  • If you don't have an ultrasonic cleaner handy, submerge them in 91+% IPA for 24 hours and stir them periodically.
  • If you do have a cleaner (and don't want to mess it up), put the bearings in a ziploc, fill it with enough IPA to submerge them, and put that in the cleaner. Mine is a jewelry cleaner and only runs for 8 minutes at a time, 4 rounds got them good and clean.
• Have something to weight them down to hold them in place. They won't fall over like the buffered spool I tried, but they will slide around. I pushed them up against the wall and set some old dive weights in front of them and that worked well enough.

You'll need to play with the spring tension, but I don't know how to tell you to test it. One spool (my first) I set to 10 (for no particular reason) and it seemed to do well. The second spool I only set to 5 (if that high) and there is quite a bit of filament that didn't make it back onto the spool. The first spool has maybe a single wrap that didn't make it back while the second has 4 or 5. Too loose and you obviously can have some tangle problems, too tight and I expect it might pull the filament out during a tool change.

Changes I can see that I want to make:

• https://www.thingiverse.com/thing:3233579
  • I would also make an adapter for the bases of the spools for the other end of the PTFE tube and would obviously switch back to the long tubes.
• Make an arm to better keep the PTFE/filament from the print area.
  • Something approaching the full height of the print area placed at the rear of the plate would hit tubes as they are right now.
  • I think it would also help with concerns about where the filament ends up going.

RE: Extremely disappointed with MMU2S

I would just like to know how anyone at Prusa ever had reliability enough for a 5 color print over 1 hour long with color changes every 5 or so minutes to ever allow this product to be sold. We all know this release was delayed for extended beta testing but it's an absolute failure, it does not work. I've used the adapters on the filament trays to prevent the filament from back flowing, no need for the retractable filament holder. I also put the attachment on just behind the ptfe tubes at the MMU2 to keep them from bending and causing any unusual feed angles on the filament. Things all look like they are fine for a while and then it stops loading again. Somewhere in the chain the filament is either malforming in shape causing issues or who knows what.

This is simply something I would not expect Josef Prusa to be putting his name on. I would not be selling it, I'd pull it from the market and get it done right. Make the MMU2 needs dual bondtechs like the extruder? Maybe a wider channel to ensure the filament angle is not an issue so it can go into the opposing PTFE with FINDA probe. Why are we all guessing on spring tension on these screws such as on the MMU2 that if too tight you get all flashing orange lights?

This is not Prusa quality. This is not something you pay $300 for and I will ask for a refund. Sorry but this is a very clear defective product.

RE: Extremely disappointed with MMU2S

I totally get where you are coming from and wish the marketing would make it's state more clear, but I think there are some important things to consider when you start saying things like "This is simply something I would not expect Josef Prusa to be putting his name on".

The implementation of multi-material with a single extruder concept is still new and there are only two commercial options at this time. The Palette seems to have just as many issues as the MMU, is almost twice the cost, and seems to have far worse support (e.g. you can probably get your money back for the MMU, you'd be stuck if you were in the same boat with the Palette if forums and Amazon reviews are even close to accurate).

Remember also that Jeff was helping lead the charge in 3D printers for the masses and the early printers were definitely not for the faint of heart (why I've only recently gotten into it even though I've been watching from the cheap seats for a long time). Even looking at the printers sold by Jeff's company, the MK3 didn't suddenly materialize in all it's glory. There have been multiple iterations where it progressively got easier to use.

I think MMU style printing is where consumer 3D printing in general was 5-10 years ago. It works, but it still has improvements to make.

I too am frustrated (I got one good print, but I'm not holding my breath until I get some more done) and I too based my expectations on the reputation of Prusa now rather considering that we are still in the early days of MM printing. Even though I'm still frustrated I'm trying to keep all that in mind as well as the fact that there are those out there that report that there are rainbows and unicorns on the other side when we get past all the initial headaches.

I'm sorry to see you give up on it, but I totally get it as I continue to hold that in my back pocket for now. On the global scale we are close together, but Northern VA is unfortunately too far to offer to commiserate and compare setups in person to try to help you out.

RE: Extremely disappointed with MMU2S

Posted by: NealC

I would just like to know how anyone at Prusa ever had reliability enough for a 5 color print over 1 hour long with color changes every 5 or so minutes to ever allow this product to be sold.

Well, I am not a PR employee, but I was on the beta test programme.

Have a look here: http://www.kisslicertalk.com/viewtopic.php?f=15&t=2371 for some pretty good prints, including 5C and 60+ hours.

Peter

RE: Extremely disappointed with MMU2S

Posted by: gnat

I finally got a successful 2 color print!

It's not flawless and I did have to help one filament change, but I finally got a print!

There are 3 things that I changed since my last attempt:

• Switched to auto rewind spools.
• Used a mod for the extruder idler door that added a bit to the tab that trips the IR sensor and then filed it down for more consistent sensor readings. It's also looser than the original which allows filament to move through the gears easier. 
• Changed a setting for one of the retraction speed options to make it move faster when changing tools. 

I forget the name of that last setting, but I'll post it later when I pull out my laptop. 

Filament Setting -> Advanced -> Unloading speed at the start = 120mm/s

I have no idea what that setting really does, but I the explanation that the person that posted it gave seemed to make sense. So I can't say if this fixed anything or not, it's just one of the changes I did make.

RE: Extremely disappointed with MMU2S

Just throwing my two cents in here...My MMU2 to MMU2S upgrade was bumpy, but mostly because my MK3 has seen heavy use for over a year and rebuilding the extruder uncovered some problems with partly broken wires. I wound up replacing my hot block and PINDA.

But now that I'm back up and running the MMK2S has been a definite improvement. Filament changes have been more reliable and the only error was recoverable with no defect in the final print.

However, it's worth noting that I started with a well-tuned MMU2. The MMU2 is a tricky beast, and it's picky about little things like how tight the idler cover is screwed down. There's still some gremlins, but far fewer today than with the first MMU2 units.

This still isn't something that's plug-and-play, and it's going to require some tinkering. But I like the trajectory we're on, and we're getting close to the point where a well-tuned unit in the hands of someone experienced in how to use it can be confident of getting perfect prints most of the time.

RE: Extremely disappointed with MMU2S

Posted by: peter.l22

However, it's worth noting that I started with a well-tuned MMU2. The MMU2 is a tricky beast, and it's picky about little things like how tight the idler cover is screwed down.

How tight should it be screwed down?

RE: Extremely disappointed with MMU2S

It's not much, but I ran off the clutch and dial of a third auto rewind spool last night (will do the forth this evening and fifth probably tomorrow night) with no issues. All layer changes happened with no assistance.

I adjusted the clutches on both the existing spools to 11 and there was no unspooled filament like I had with the dual color Benchy. 

The only issue I've had is that after finishing the base and hub, the PTFE holder pulled away from the extruder during the post print retraction and prevented the filament from retracting properly. I tightened it back down (with a wrench this time) and it started the next single color print with no assistance. 

I tend to give credit to the spool holders, but I suspect the new door on the extruder that allows better movement and more reliable IR function is really what helped the most. 

So my advice is to get the printer dialed back in and happy without the MMU installed. Pay close attention to that door and the IR sensor state. Once everything is smoothly operating, then add the MMU. That should give you less to tweak and focus on. 

RE: Extremely disappointed with MMU2S

Posted by: PJR

Well, I am not a PR employee, but I was on the beta test programme.

Have a look here: http://www.kisslicertalk.com/viewtopic.php?f=15&t=2371 for some pretty good prints, including 5C and 60+ hours.

 

Peter

Does This Kiss slicer have built-in profiles? If not, can you post yours? I am going to try that slicer next.

I havr a MMU2S with an MK3 and the S upgrade kit.

RE: Extremely disappointed with MMU2S

Posted by: Spectere

https://www.thingiverse.com/thing:3233579

I printed this last night and it drastically improved the filament path into the back of the selector. The PTFE tube installation went from being incredibly finicky to being simple and reliable. Just install the mod, screw in the couplers, make sure the ends of your tubes are properly trimmed, and push it until it presses against the selector. Done.

I'm probably going to print the spool holders that Gnat recommended as well, since the buffer is just...bad. It's a pain to load and seems to introduce some drag if conditions aren't perfect.

I also ended up ordering a Palette 2 Pro (I have some non-Prusa printers, so it'll still get plenty of use if my modded MMU2S proves to reliable), so I'll be able to compare the two of them fairly shortly.

RE: Extremely disappointed with MMU2S

Posted by: CybrSage

Does This Kiss slicer have built-in profiles? If not, can you post yours? I am going to try that slicer next.

 

I havr a MMU2S with an MK3 and the S upgrade kit.

 

My older Mk3 profiles are online on the main KISS site.  I will be making the "S" profiles available shortly.

Peter

RE: Extremely disappointed with MMU2S

I agree with nealc, I am very happy with the MK3s but the mmu2s is quite an other story.

I am using now my upgraded MK3s/mmu2s for over a month and tested it over and over including all the tips, tricks and user mods from this forum! I have to say the mmu2s is not a Prûsa Reseach quality product we are all used to. Sorry Josef you set the quality standards earlier yourself:) My conclusion is that the mmu2s is fine if you want to research a 3D printer yourself and have enough time! But the story rapidly changes if you have customers waiting for a multi coloured print. For the moment I switched back to the MK3s/MMU2s singel mode and wait for really good upgrade. They major problems I encountered are:

- Filament loading and unloading is extremely sensitive at the mmu2s unit and also dependent of the type of filament used. The filament path and transport in the mmu2s needs a serious redesign, even the layers of the 3D farm printed parts are causing serious problems! 

- The interaction between the mmu2s and the mk3s extruder and sensors during loading/unloading is not working correctly, probably a software issue.

- Forget for the moment extensive use of the PTFE tubings. Depending on the total length of the tubings from spool to extruder the friction will be very high. Poor bondtech gears!! Forget all kind of buffers just use push true Pneufits 10mm with short tubings when needed and use the PTFE tubes trick as a temporary buffer.

RE: Extremely disappointed with MMU2S

I expended a lot of hours trying different things and many hours printing without success (throwing a lot of falied prints filament)

I am really tired of it.

When I had the MMU2 finally I disconnected it.

When I listen about MMU2S upgrade I was excited again. I paid for the printed parts to sure they were perfect.

I upgraded my printer... It is not perfect perpendicular any more. I don't know what happened... It continues printing well but I would like to have any gide about how to correct it.

The MMUs continues failing. I am feeling that my MK3s is suffering the effects (nozzel stucks, many hours printing for nothing, changes and upgrades) and getting less reliable because of trying to make it work.

There are a lot of suggestions and ideas to make it work but I really miss an official guide for troubleshooting (I found the manual incomplete)

At this point I would return MMU if I had the option. I know that it is less expensive than the pallete2 and I prefer to support prusa but in my case the problems around MMUs make it not being worth it at all. At the end I can not print multimaterial and this was what I paid for.