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MMU2 ruining my enjoyment of printing  

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elvin.v
(@elvin-v)
New Member
MMU2 ruining my enjoyment of printing

Hi all,

Since a few weeks i upgraded my MK3 to a MK3s with MMU2. The update had been laying around for a few months due to lack of time.

Finnaly assembled it and started testing it. I really like the prusa products, but this one really sucks. Didnt knew what i needed to do with the buffer assembled. It's not mentioned in assembly instruction.

At the end of the assembly instruction they point to the middle of the mmu2 manual about the IR sensor calibration (chapter 7). Why not mention this in the preflight check? It weird to start halfway into the manual. Didn't have any idea how to load the filament with the mmu, but the chapter 7 says that you have to load the PLA... Still didn't knew what to do with the buffer.

At chapter 3 I discovered that the buffer takes a lot of space, wich i don't have. When you order the MMU2, nothing is mentioned about the 70x100m thats needed. Also loading into the buffer is almost impossible with tangeling filament.

So i decided to print the autorewind spoolholder. After printing a few parts the MMU2 doesn't load to the nozzle anymore. When loading to the nozzle it stops around the IR sensor en then spools it back. All kind of light sequences are flashing on the MMU2. Can't find any good explanation of the flashing lights. Sometimes its just eating the filament, causing a dent in the filament and it cant move it cause of no grip. 

I live on the third floor and almost trew it out of the window. It a piece of crap, unable to work with it. Waste of money. Badly written manual. When i search for MMU2 i only find people with troubles with the MMU2.

 

Please point me to decent manual about loading and printing with the mmu, im fucking annoyed about it.

Posted : 15/11/2019 9:38 am
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Joe Prints
(@joe-prints)
Estimable Member
RE: MMU2 ruining my enjoyment of printing

It should be assumed that since it prints with up to 5 spools you will need some room.

As for the filament coming up short- I have found that the best way to calibrate it is to enter the MMU2 calibration menu( https://manual.prusa3d.com/Guide/Service+menu+-+Individual+Filament+Calibration/842 ) and load the filament for each "slot" until it triggers on the LCD(Support>Sensor Info) Also check the MMU2 idler tension

What do your tips look like? Badly shaped tips can show up as a monotony of things "wrong"

Hope this helps keep your sanity.

Anything can be made better
https://www.myminifactory.com/users/Joe%20Prints

Posted : 15/11/2019 3:49 pm
gnat
 gnat
(@gnat)
Noble Member
RE: MMU2 ruining my enjoyment of printing

So first I will say that it sounds like you have an issue with your extruder, likely the IR sensor needs some help. I STRONGLY suggest looking into the LED mod for the IR sensor as it makes diagnosing and tuning the IR sensor much easier.

Next, I started off similar to you and initially wrote off the buffer, but it actually doesn't have to take up much space. I don't have a good picture, but I built a 2020 frame to hold my spools above the printer. I found, however, that the rewind spools I was using weren't working as well up there, so I modified a part on the buffer so I could hang it off the back of the frame. Once I got the buffer->MMU path dialed in (switched to Capricorn XS and am using M10 pass through fittings on the MMU and buffer) it has been working great with minimal change in the footprint of the printer.

Picture of the frame:

Buffer hanging off the back:

The link in my sig has some pointers to things to look at and tweak.

I would suggest you start by disconnecting the MMU and printing as a normal MK3S. Once you can get through reasonable test prints (I use a 20x20x20 cube) without the printer falsely thinking it has run out of filament you probably have the IR sensor close to dialed in and can add the MMU back into the mix. While testing and/or before re-adding the MMU is also a good time to print other parts (e.g. a rewind spool or two) that you want to use.

Then start simple with the MMU and work your way up. Make sure you can get trouble free single color prints out of all the tools. Then move up to a simple (<50 tool changes) 2 color print. Read up on filament tips so you can examine them and make appropriate adjustments. Then keep tweaking and work your way up to your first 5 color print. Aim for tests that can print in under 30 minutes so it's not too painful to hang out and watch it and also so a late failure doesn't mean an entire day has been wasted.

As far as the title of the thread, yeah me too. I had my MK3 running almost non-stop the first 6 months I had it, then the MMU showed up. While I did get it working nice and smoothly after a few weeks, the printer has been mostly idle for the last 5 months. My issue, however, is more in converting single objects into multi-material prints. I'm not much of an object designer so most of my prints are of other people's objects, but I have had no success "coloring" other people's objects and have wasted a ton of time trying to.

MMU tips and troubleshooting
Posted : 15/11/2019 8:29 pm
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