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  1. Welcome to the tutorial on how to upgrade your single material Original Prusa i3 MK3S/MK3/MK2.5S/MK2.5 to Original Prusa i3 MK3S/MK2.5S MMU2S
    • Welcome to the tutorial on how to upgrade your single material Original Prusa i3 MK3S/MK3/MK2.5S/MK2.5 to Original Prusa i3 MK3S/MK2.5S MMU2S

    • Directly compatible printers:

    • Original Prusa i3 MK3S and MK3

    • Original Prusa i3 MK2.5S and MK2.5

    • Incompatible printers:

    • Original Prusa i3 MK2/S (please upgrade first to MK2.5S)

    • Original Prusa i3 MK2/S MMU1 (please use a different package MMU1 to MMU2S)

    • For those upgrading MMU2 to MMU2S, please follow chapters 2 and 3 to rebuild the extruder, then skip to chapter 6 (around step 22), assemble buffer in 7 and calibrate printer according to chapter 8.

  2. The kit includes:
    • The kit includes:

    • Needle-nose pliers (1x)

    • Philips screwdriver (1x)

    • Allen key (4x)

    • 8mm wrench

    • No soldering is required.

    • No wire crimping is required.

    • The colour of the tools might differ.

  3. Most of the labels are scaled 1:1 and can be used to identify the part :-)
    • Most of the labels are scaled 1:1 and can be used to identify the part :-)

    • Label on the picture is used as an example, yours might be different.

  4. When you browse the guide on manual.prusa3d.com, you can view the original  images in high resolution for clarity.
    • When you browse the guide on manual.prusa3d.com, you can view the original images in high resolution for clarity.

    • Just hover your cursor over the image and click the Magnifier button ("View original") in the top left corner.

  5. Original Prusa i3 MK3S/MK2.5S MMU2S has most of the 3D printed parts marked with their version.
    • Original Prusa i3 MK3S/MK2.5S MMU2S has most of the 3D printed parts marked with their version.

    • In case you have issues while printing or assembling certain printed part, please try to find this label and tell it to our support team.

    • Printed parts in the picture are used as an example, yours will be different.

  6. All parts necessary to finish this upgrade are included in the kit. Only exception is that if you are upgrading MMU2 to MMU2S and decided to print the parts on your own. In case some parts get broken during the assembly, you can reprint them. Please check all plastic parts before starting your build to make sure there are no issues. The package with all MMU2S STL files  is available at prusa3d.com/prusa-i3-printable-parts/
    • All parts necessary to finish this upgrade are included in the kit. Only exception is that if you are upgrading MMU2 to MMU2S and decided to print the parts on your own.

    • In case some parts get broken during the assembly, you can reprint them. Please check all plastic parts before starting your build to make sure there are no issues.

    • The package with all MMU2S STL files is available at prusa3d.com/prusa-i3-printable-parts/

    • The recommended material is PETG, but you can use also ABS or any material with similar properties to PETG.

    • For printing individual parts, it is recommended to use Slic3r PE with 0.2 mm layer height, GRID infill at 20%, no supports!

  7. Lost in the instructions, missing screws or a cracked printed part? Let us know! You can contact us using following channels:
    • Lost in the instructions, missing screws or a cracked printed part? Let us know!

    • You can contact us using following channels:

    • Using comments under each step.

    • Using our 24/7 live chat at shop.prusa3d.com

    • Writing an email to info@prusa3d.com

  8. 3D printed parts are very precise, however, there still might be a tolerance in the printed part and same goes for the size of the nut. Therefore it might happen, that the nut won't fit easily in or might be falling out. Let's see, how to fix it: Nut won't fit in: use a screw with a thread along its entire length (typically: M3x10, M3x18) and screw it from the opposite side of the opening. While tightening the screw, the nut will be pulled in. Remove the screw afterwards.
    • 3D printed parts are very precise, however, there still might be a tolerance in the printed part and same goes for the size of the nut.

    • Therefore it might happen, that the nut won't fit easily in or might be falling out. Let's see, how to fix it:

    • Nut won't fit in: use a screw with a thread along its entire length (typically: M3x10, M3x18) and screw it from the opposite side of the opening. While tightening the screw, the nut will be pulled in. Remove the screw afterwards.

    • Nut keeps falling out: Use a piece of tape to fix the nut temporarily in place, as soon as you insert the screw in, you can remove the tape. Using glue isn't recommended as it can partly reach into the thread and you won't be able to tighten the screw properly.

    • Every time we recommend to use the "screw pulling technique", you will be reminded with Joe's avatar ;)

    • Parts in the pictures are used as an example.

  9. Building a 3D printer is a challenge unlike any other and you should treat yourself for every milestone you reach. That is why a bag of Haribo Bears is included!
    • Building a 3D printer is a challenge unlike any other and you should treat yourself for every milestone you reach. That is why a bag of Haribo Bears is included!

    • The biggest issue from the previous builds (MK3, MK2/S) which we had to address was inadequate bear consumption. Many of you didn't have enough bears for all chapters, some even ate them all before they started!

    • I'm glad to announce that after countless weeks of academic research (hundreds of eaten bears), we came to a solution! Thank us later ;)

    • At the end of each chapter, you will be told a specific amount of bears to consume.

    • Eating more or less bears than prescribed in the manual might lead to fatigue or nausea. Please consult a professional in the closest candy store.

    • Hide the Haribo for now! From our experience an unattended bag with sweets tends to suddenly disappear. We are currently investigating this phenomenon.

  10. To successfully finish the assembly please follow all these: Always read all the instructions at current step first, it will help you to understand, what you need to do.
    • To successfully finish the assembly please follow all these:

    • Always read all the instructions at current step first, it will help you to understand, what you need to do.

    • Don't follow pictures only! It is not enough, the written instructions are as brief as they could be. Read them.

    • Read the comments from the other users, they are great source of ideas. We read them too and based on your feedback improve the manual and the entire assembly.

    • Use a reasonable force, the printed parts are tough, but not unbreakable. If it doesn't fit, check your approach twice.

    • Eat the gummy bears as instructed! Disobedience won't be tolerated :D

    • Most important: Enjoy the build, have fun. Cooperate with your kids, friends or partners. However, we take no responsibility for possible fights ;)

  11. IMPORTANT: Make sure you have selected correct printer from below! MK3/MK2.5 design with "chimney" and two idler screws requires complete extruder disassembly. You have to use new printed parts. Please follow 2A. MK3/MK2.5 - extruder disassembly
    • IMPORTANT: Make sure you have selected correct printer from below!

    • MK3/MK2.5 design with "chimney" and two idler screws requires complete extruder disassembly. You have to use new printed parts. Please follow 2A. MK3/MK2.5 - extruder disassembly

    • If you start with the old MK3/MK2.5 printer, then follow the chapters with this type of the printer (chapters “A”)

    • MK3S/MK2.5S design without "chimney" and one idler screw requires partial extruder disassembly. You have to replace just few parts. Please follow 2B. MK3S/MK2.5S - extruder disassembly

    • If you start with the new MK3S/MK2.5S printer, then follow chapters with this type of the printer (chapters “B”)

Finish Line

501 other people completed this guide.

Jakub Dolezal

Member since: 02/20/2017

225 Guides authored

Team

Prusa Research Member of Prusa Research

Community

3 Members

367 Guides authored

13 Comments

It seems to me that the published upgrade process could be improved by largely completing the assemblies before dismantling the extruder, which takes the printer out of service until the process is complete.

Is there a good reason why the upgrade should be carried out in this way?

Les Grosvenor - Reply

Hi Les, you need parts from the old extruder to assemble the new one. If you know what to do, then you can initially omit them.

Filip M - Official Prusa CS -

Ok Filip,

Thank you for speedy response. I will follow my modified build order while continuing to print parts until the final stage , when partial dismantling of the extruder becomes essential to procede with the upgrade.

Les G

Les Grosvenor - Reply

Suggestion: for those who are upgrading using self-printed parts, could be good to have here, at this moment, a set (or a link to) of parts’ images (with its names) to act as a checklist, since they do not come with the kit and the download page is not so clear (especially if you are doing more than one upgrade at same time).

Gutenberg Barros - Reply

That seems like a good idea, I will pass it upstream.

Martin L. - Official Prusa CS -

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