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1. Introduction

1. Introduction
Relevant for:
Last updated 12 days ago
1. Introduction
 Available languages

Step 1 Preparing the upgrade kit

Preparing the upgrade kit
Preparing the upgrade kit
Welcome to our step-by-step guide on upgrading your Original Prusa i3 MK3S/MK3S+ to the Original Prusa MK3.5.
This upgrade manual is intended for MK3S and MK3S+ printers only. The MK3 version is not supported.
Prepare the upgrade kit received from Prusa Research.
WARNING: Before you start disassembling the printer, ensure that you have successfully printed all the required parts for the upgrade.

Step 2 Getting the necessary tools

Getting the necessary tools
Getting the necessary tools
Getting the necessary tools
Tools required for the upgrade are:
Needle-nose pliers (1x)
Philips (PH2) screwdriver (1x)
Universal wrench (1x)
2.0mm Allen key
2.5mm Allen key
T10 / T8 Torx key

Step 3 Labels guide

Labels guide
Labels guide
Labels guide
All the boxes and bags including parts for the build are labeled.
The labels include the list of contents and part count.
You can download a Cheatsheet with 1:1 fastener drawings from our site prusa.io/cheatsheet-mk4. Print it at 100 %, don't rescale it, otherwise, it won't work.
For PRUSA veterans: Fasteners are divided into individual bags according to its type. Not into packages for individual chapters, as it was with previous printers.

Step 4 Spare bag

Spare bag
Spare bag
Spare fasteners are included in each bag of fasteners.
At the end of this manual, you'll find a helpful list detailing any extra fasteners remaining in the package. It will prevent you from worrying that you have more than one of the same type of fasteners left.
There is a bag with spare parts like thermal pads, springs, etc.

Step 5 Printed parts - self printing

Printed parts - self printing
Printed parts - self printing
Printed parts - self printing
Before we start disassembly, you need to print all the necessary parts.
Filaments (PETG) for printing all necessary parts are included in the UPGRADE package.
G-codes and STL files are available on our website: prusa.io/printable-parts-mk35
For printing individual parts it is recommended to use PrusaSlicer with 0.2 mm layer height, GRID infill at 15 %, no supports!
Before installing the MK3.5 upgrade in your Original Prusa Enclosure, be sure to download and print the compatible xLCD supports for Enclosure.
Find the G-code files on prusa.io/printable-parts-mk35.

Step 6 Printable parts - Silver to Black PSU

Printable parts - Silver to Black PSU
Printable parts - Silver to Black PSU
Printable parts - Silver to Black PSU
Printable parts - Silver to Black PSU
This step is for users who have purchased the black 24V 240W PSU (Power Supply Unit) and would like to replace an existing silver power supply unit during the upgrade.
For this replacement, the following parts need to be printed in addition:
PSU-cover (1x)
Download the part from PSU Upgrade category on prusa.io/printable-parts-mk35
Print the parts according to the prescribed print settings in the description on Printables.com.

Step 7 Printed parts post-processing

Printed parts post-processing
Printed parts post-processing
Printed parts post-processing
Printed parts post-processing
Some parts might require post-processing in order to be ready for assembly.
In general for all printed parts (We will use just a few parts as an example):
Each hole for a screw, nylon filament, etc. must be clean and free of any strings. If there are any remnants of filament inside the hole, hand drill the holes with a 3mm drill bit. Do not use electric power tools!
All other holes, for example for the smooth rods, must be perfectly clean. If there is any filament residue inside the hole, use a heat gun to melt it.
Optimal temperature for the heat gun is 250 °C (482 °F) and blow on the parts from a distance of 10 - 15cm (4 - 6 inches).
Check the square and hexagon nut holes. There must be no filament debris inside.
Check the parts for straightness. For example, by placing it on a clean table surface. Bent parts can cause problems during installation and subsequent use of the printer.
Do not modify any parts unless instructed to do so.

Step 8 We are here for you!

We are here for you!
We are here for you!
We are here for you!
Lost in the instructions, missing screw or cracked printed part? Let us know!
You can contact us using the following channels:
Using comments under each step.
Using our 24/7 live chat here at help.prusa3d.com
Writing an email to [email protected]

Step 9 Pro tip: inserting the nuts

Pro tip: inserting the nuts
Pro tip: inserting the nuts
Pro tip: inserting the nuts
Pro tip: inserting the nuts
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.
Alternative option: you can use X-holder tool included in the package. Insert any screw (typically: M3x10 or M3x18) and screw the nut fully on the tip of the thread. Push the nut into the printed part and remove the screw with X-holder.
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 using the "screw pulling technique", you will be reminded with Joe's avatar ;)
Parts in the pictures are used as an example.

Step 10 View high resolution images

View high resolution images
View high resolution images
When you browse the guide on help.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.

Step 11 Important: Electronics protection

Important: Electronics protection
Important: Electronics protection
WARNING: Make sure to protect the electronics against electrostatic discharge (ESD). Always unpack the electronics right before you need them!
Here are some tips to prevent damage to the electronics:
Keep the electronics inside the ESD bag right until you are asked to install them.
Always touch the sides of the board only while handling it. Avoid touching the components on the surface.
Before you touch the electronics use any conductive (metal) structure nearby to neutralize the possible static charge from your hands.
Be extra cautious in rooms with carpets, which are often a source of electrostatic energy.
Clothes made of wool or certain synthetic fabrics can easily gather static electricity too. It is safer to wear cotton clothing for the assembly.

Step 12 Reward yourself

Reward yourself
Reward yourself
Based on the feedback, building the MK3.5 printer is even more enjoyable compared to the MK3S+. However, you should still treat yourself for every finished chapter. Look in the box and find bag of Haribo Bears.
The biggest issue from our experience (MK3S+, MK3S, MK3, MK2S, ...) is inadequate bear consumption. Many of you didn't have enough gummy bears for all chapters, some even ate them all before they started!
After years of thorough scientific research, we came to a solution => At the end of each chapter, you will be told a specific amount of bears to consume.
Eating incorrect amount than prescribed in the manual might lead to sudden boost of energy. Please consult a professional in the closest candy store.
Hide the Haribo for now! From our experience an unattended bag with sweets will suddenly disappear. Confirmed by multiple cases all around the World.

Step 13 How to successfully finish the assembly

How to successfully finish the assembly
How to successfully finish the assembly
To successfully finish the upgrade please follow all these:
Always read all the instructions at the current step first, it will help you to understand what you need to do. Don't cut or trim unless you are told to!!!
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 a 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.

Step 14 Prepare your desk

Prepare your desk
Prepare your desk
Tidy up your desk! Tidying up decreases the probability of losing small parts.
Clear your workspace. Make sure you have enough room. A nice clear flat workbench will get you the results you are aiming for.
Let there be light! Make sure you are in a well-lit environment. Another lamp or even an extra flashlight will probably come in handy.
Prepare something to contain the plastic bags and the removed packing materials so you can recycle them afterwards. Make sure there are no important parts being discarded.
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