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  1. Welcome to the tutorial how to upgrade your Original Prusa i3 MK3 to Original Prusa i3 MK3S Please prepare the upgrade kit received from Prusa Research.
    • Welcome to the tutorial how to upgrade your Original Prusa i3 MK3 to Original Prusa i3 MK3S

    • Please prepare the upgrade kit received from Prusa Research.

    • WARNING: This assembly guide is valid ONLY FOR SINGLE MATERIAL MK3S!!! For MK3S MMU2S, please follow this guide Original Prusa i3 MK3S/MK2.5S & MK3/MK2.5 to MMU2S Different parts are needed!

    • This MK3 to MK3S upgrade focuses only on the new Extruder design. Other parts of the printer can differ from yours, but there is no need to upgrade them.

  2. For this upgrade you will need:
    • For this upgrade you will need:

    • Needle-nose pliers (1x)

    • Allen key 2.5 mm (1x)

    • Allen key 2.0 mm (1x)

    • Allen key 1.5 mm (1x)

    • Slotted screwdriver for the belt insertion (optional)

    • No soldering is required. No wire crimping is required.

    • Tools are not included.

  3. All the boxes and bags including parts for the build are labelled.
    • All the boxes and bags including parts for the build are labelled.

    • This bag is used as an example.

  4. Most of the labels are scaled 1:1 and can be used to identify the part :-) For the most common screws, nuts and PTFE tubes. You can also use the enclosed letter, which contains Prusa Cheatsheet on the other side.
    • Most of the labels are scaled 1:1 and can be used to identify the part :-)

    • For the most common screws, nuts and PTFE tubes. You can also use the enclosed letter, which contains Prusa Cheatsheet on the other side.

    • You can download Prusa Cheatsheet from our site. Print it at 100 %, don't rescale it, otherwise it won't work.

  5. 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.

  6. Most of the 3D printed parts on  Original Prusa i3 MK3S are marked with their version.
    • Most of the 3D printed parts on Original Prusa i3 MK3S are marked with their version.

    • Cx series (e.g. C1) - those parts are printed on Prusa Research farm and are distributed with the kit.

    • Rx series (e.g. R4) - those parts are available for download and printing by the user. They are identical to the factory ones.

    • In case you have issues while assembling the printer with the 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 might be different.

  7. Before we start disassembly, you need to print (or purchase) all the necessary parts. If you already have the parts, you can skip to the next step. For MK3 to MK3S upgrade you need to print the extruder parts, which are separated into more G-codes. Use enclosed BLACK PETG or similar material. The colour should be black to avoid issues.
    • Before we start disassembly, you need to print (or purchase) all the necessary parts. If you already have the parts, you can skip to the next step.

    • For MK3 to MK3S upgrade you need to print the extruder parts, which are separated into more G-codes. Use enclosed BLACK PETG or similar material. The colour should be black to avoid issues.

    • G-codes and STL files are available on our website: prusa3d.com/prusa-i3-printable-parts

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

    • Fan-shroud must be printed from ABS only!!! We include this part in the upgrade package.

    • No need to print the Y-axis parts, their main purpose is easier assembly.

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

  9. 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.

  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.

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

    • READY? You can start by 2. Extruder disassembly

Finish Line

371 other people completed this guide.

Jakub Dolezal

Member since: 02/20/2017

222 Guides authored

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Prusa Research Member of Prusa Research

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364 Guides authored

2 Comments

Quick video on what’s in the box: https://youtu.be/zBUYRfBipKM

Byron Wingerd - Reply

What is the reasoning behind the allocation of items to the 2 plates? Why are they so unevenly populated?

Len - Reply

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