Prusa Research Original Prusa MK4 User manual

3D PRINTING
HANDBOOK
FOR THE ORIGINAL PRUSA MK4 3D PRINTER
ORIGINAL INSTRUCTIONS
ENG

Original Prusa MK4: Official Instructions
Version 1.01 - March 30th, 2023
The latest version of the MK4 handbook can always be found at prusa3d.com/drivers.
Quick Guide to the First Print
Read the Safety Instructions carefully (page 8)1.
Place the printer on a flat and stable surface (page 13)2.
Download the latest firmware from prusa3d.com/drivers and install it (page 30)3.
Calibrate the printer using the Selftest Wizard (page 19)4.
Insert the USB drive that came with your printer and print your first object (page 25)5.
Tips, advice or important information that will help you when working with the printer.
This part of the text is very important, please read it carefully! It is directly related to the correct
operation of the printer and its safe operation.
This information applies to the Original Prusa MK4 3D printer assembly kit.
How to contact Prusa Research technical support:
First, check the last sections of this manual that deal with common problems, or go to
https://help.prusa3d.com where you will find a complete list of the most common problems
and their solutions. If your problem is not listed here, or the solution does not work, please send
an email to [email protected] and/or use our chat at prusa3d.com. Try to describe your
problem as accurately as possible - ideally include pictures or videos.
JOSEF PRUSA®, PRUSA RESEARCH®, PRUSA POLYMERS®, PRUSA ORANGE®, ORIGINAL PRUSA®, PRUSA 3D®, and PRUSAMENT® are registered
trademarks of Prusa Development a.s. used by Prusa Research a.s. under license from Prusa Development a.s. | JOSEF PRUSA, ORIGINAL PRUSA, and
PRUSAMENT are registered trademarks (or trademark applications) of Prusa Development a.s. and are used by Prusa Research a.s. under license from Prusa
Development a.s. in the following countries: Australia, New Zealand, Israel, Mexico, South Korea, Turkey, Ukraine, Russia, Kazakhstan, Switzerland, China,
Colombia, Uzbekistan, Philippines and Norway. | All other company names and product names mentioned in this publication are trademarks and registered
trademarks of their respective companies.

About the Author
Josef Průša (*23. 2. 1990) became interested in 3D printing when he began studying at the
University of Economics in 2009 - it started off as a hobby, a new technology open to
modifications and improvements. The hobby quickly became his passion, and Josef became one
of the main developers of the international open-source (all works are freely available for any use)
RepRap project by Adrian Bowyer. Today, Prusa's design in various versions can be seen all over
the world; it is one of the most used printer designs. The goal is to increase public awareness of
3D printing technology.
All of Josef Průša's 3D printers are open-source. In the spirit of the RepRap project, you can use
your printer to produce parts for other 3D printers. The Original Prusa product range is constantly
being expanded with new models and improvements.
His main goal is to make 3D printing technology more understandable and easier for ordinary
users. Josef Průša also holds workshops for the public, participates in professional conferences,
and promotes 3D printing. He has lectured at TEDx conferences in Prague and Vienna, at the
World Maker Faire in New York, at the Maker Faire in Rome, and at the Open Hardware Summit
at MIT. He has also taught the Arduino course at Charles University and was a lecturer at the
Academy of Arts, Architecture and Design in Prague.
In his own words, he envisions a not-so-distant future where 3D printers will be available in every
household. If anything is needed, you can easily print it out. The boundaries in this field are being
pushed every day… We are glad you are part of it!

Table of contents
1. Introduction 11 ..............................................................................................................................................................
1.1. Nextruder 11 ........................................................................................................................................................
1.2. Quick-Swap Nozzles 12 ................................................................................................................................
1.3. 32-bit Connected Architecture 12 ...........................................................................................................
2. Unpacking and Package Contents 13 .............................................................................................................
2.1. How to Move the Printer 13 .........................................................................................................................
2.2. Contents of the Package and Accessories 14 ....................................................................................
3. Original Prusa MK4 Overview and Glossary 15 .........................................................................................
3.1. Connecting and Disconnecting the Power Cable 17 .......................................................................
3.2. Error Screens 17 ..............................................................................................................................................
4. Your First Print 18 ......................................................................................................................................................
4.1. Basic controls 18 ..............................................................................................................................................
4.2. Selftest Calibration (Wizard) 19 ...............................................................................................................
4.3. Preparing Flexible Print Sheets 20 .........................................................................................................
4.4. Running the Selftest 21 ................................................................................................................................
4.5. Inserting (Loading) filament 22 ................................................................................................................
4.6. Unloading (Removing) Filament 24 ........................................................................................................
4.7. Starting the First Print 25 ............................................................................................................................
4.8. Removing a Printed Object from the Print Sheet 27 ......................................................................
4.9. Selftest Troubleshooting 28 ......................................................................................................................
4.10. First Print Troubleshooting 28 ................................................................................................................
4.10.1. First layer peeling off from the bed 28 ....................................................................................
4.10.2. Nozzle moves too high/low, or extrudes plastic outside the print area 28 ...........
4.10.3. The nozzle does not start extruding, even after multiple attempts 29 ....................
4.10.4. After a few hours of printing, the nozzle stops extruding filament 29 ....................
4.11. Updating the Firmware 30 ........................................................................................................................
4.12. Sample Models 31 ........................................................................................................................................
4.13. Factory Reset 31 ............................................................................................................................................
5. Advanced User Guide 32 .......................................................................................................................................
5.1. Prusa Academy Courses 32 ........................................................................................................................
5.2. Network Connection 33 ...............................................................................................................................
5.3. Using Nozzles with Various Diameters 34 .........................................................................................
5.4. Multi-Material Upgrade 3 35 .....................................................................................................................
5.5. Flashing an Unofficial (Unsigned) Firmware: 36 ..............................................................................
6. Printing Your Own Models 37 .............................................................................................................................
6.1. Obtaining Printable Models 38 .................................................................................................................
6.2. Create Your Own Model 39 .......................................................................................................................
6.3. What is a G-code File? 39 ..........................................................................................................................
6.4. PrusaSlicer 40 ..................................................................................................................................................
6.5. PrusaSlicer Interface Explained 41 .........................................................................................................
6.5.1. Initial Setup and General Workflow 42 ....................................................................................
6.5.2. Using Supports 43 ............................................................................................................................
6.5.3. Speed vs Print Quality 44 ...............................................................................................................
6.5.4. Infill 45 ....................................................................................................................................................
6.5.5. Brim 45 ...................................................................................................................................................
6.5.6. Printing Objects Larger than the Print Volume 46 .............................................................
6.5.7. Printing Multicolored Objects (without MMU3) 47 ............................................................
6.5.8. Slicing and Exporting 48 ................................................................................................................
7. Material Guide 49 ......................................................................................................................................................

7.1. PLA 49 ...................................................................................................................................................................
7.2. PETG 50 ..............................................................................................................................................................
7.3. ASA (ABS) 51 ....................................................................................................................................................
7.4. PC (polycarbonate) and PC Blend 52 .....................................................................................................
7.5. PVB 53 .................................................................................................................................................................
7.6. Flexible Materials 54 ......................................................................................................................................
7.7. PA (Polyamide) / PA11CF 55 ......................................................................................................................
8. Regular Maintenance 56 .......................................................................................................................................
8.1. Flexible Print Sheets 56 ................................................................................................................................
8.1.1. Double-Sided TEXTURED Print Sheet 58 ..............................................................................
8.1.2. Double-Sided SMOOTH Print Sheet 58 ..................................................................................
8.1.3. Double-Sided SATIN Print Sheet 59 ........................................................................................
8.1.4. Improving the Adhesion 59 ............................................................................................................
8.2. Keeping the Printer Clean 59 ....................................................................................................................
8.3. Bearings 59 .......................................................................................................................................................
8.4. Fans 60 ................................................................................................................................................................
8.5. Extruder Feeding Gear 60 ..........................................................................................................................
8.6. Electronics 60 ...................................................................................................................................................
8.7. Extruder is Clogged or Jammed 60 ........................................................................................................
8.8. Cleaning the Nozzle 61 .................................................................................................................................
8.8.1. The filament does not come out of the nozzle. 61 ...............................................................
8.8.2. The filament does not come out of the nozzle or only a small amount comes
out 61 ...........................................................................................................................................................
8.9. Troubleshooting Faulty Sensor Readings and Removing Errors 61 ........................................
8.10. Filament Sensor 61 ......................................................................................................................................
9. FAQ - Frequently Asked Questions and Basic Troubleshooting 62 ..............................................
9.1. Mesh Bed Leveling Fails 62 ........................................................................................................................
9.2. Printer Does Not Recognize the Inserted USB Drive 62 ..............................................................
9.3. Loose Belts 63 ..................................................................................................................................................
9.4. Homing Failed 63 ...........................................................................................................................................
9.5. Heating Error 63 ..............................................................................................................................................
9.6. Fan Error 63 ......................................................................................................................................................
9.7. Reverting to an Older Firmware 63 ........................................................................................................
9.8. Nozzle Hitting the Sheet / Other Z-axis Issues 63 .........................................................................
10. Advanced Hardware Troubleshooting 64 ..................................................................................................
11. Troubleshooting Print Quality Issues 64 .....................................................................................................

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Safety symbols and their meaning
Careful: strong magnetic fields
Careful: mechanical parts. Take care to avoid injury to hands when in close proximity to
the device with mechanical parts.
Further information regarding function and service can be found in this user manual or
online at help.prusa3d.com.
Before any service intervention, it is necessary to first disconnect the 3D printer from the
power source and familiarize with the instructions.
Take extra care when handling or touching parts marked with this symbol, and avoid
further risks specified by specific symbols, such as hot surface hazards — burns may
occur.
Hot surface! The marked object may be hot and extra care should be taken when
touching it.
Unprotected moving mechanical parts can cause injuries, please take extra care.
Do not print directly on this surface.
High electrical currents are being switched on and off in the immediate proximity of parts
marked like this. Persons with an implanted cardiac stimulator or other devices for
controlling and regulating heart functions must take extra care and consult their doctor
before using the 3D printer.
This device is composed of components that must be disposed of in accordance with the
Directive on Waste Electrical and Electronic Equipment.

7
Product Information
Name: Original Prusa MK4
Manufacturer: Prusa Research a.s., Partyzánská 188/7a, Holešovice, 170 00
Prague 7, Czech Republic
Contacts: Phone: [phone], e-mail: [email protected]
EEE category: 3 (IT / Telecommunications Equipment), device usage: indoor use
only
Power supply: 100-240 VAC, 2.8 A max., 50-60 Hz
Operating temperature
range: 18 °C - 38 °C
Maximum air humidity: 85%, non-condensing
Printer dimensions:
Width: 460 mm
Depth (with bed centered): 420 mm
Height (without spool and spoolholder): 385 mm
Build volume (width ×
depth × height) 250×210×220 mm
Installed nozzle diameter: 0.4 mm
Supported filament
diameter 1.75 mm
Weight (without
packaging): 7.6 kg
The product serial number can be found on the type label located on the back of the printer and
on the outer packaging. This device is intended for use in indoor environments only and is
protected against external influences.
This device is intended for use in indoor environments only where it is protected against external
influences.
Warranty
The Original Prusa MK4 3D printer is covered by a 24-month warranty for end customers in the
EU, and a 12-month warranty for business customers and end customers in the rest of the world.
Consumables and parts subject to wear and tear are excluded from this warranty. The warranty
period starts on the day the customer receives the goods.
The seller is not liable for any damage caused by improper handling of the purchased product, or
damage caused by handling in violation of the information and recommendations given in the
official manuals and instructions. The warranty also expires in the event of unskilled interventions
and the use of unofficial hardware and software modifications.

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Safety Instructions and Disclaimer
Acting in contravention of the information provided in the manual may lead to injury, poor print
results, or damage to the 3D printer. Make sure that everyone working with the printer is
familiarized with the content of this handbook and understands it correctly.
As we cannot control the conditions under which the Original Prusa MK4 printer is used, we do
not assume any responsibility and expressly disclaim any liability for losses, injuries, damages or
expenses arising out of or in connection with the assembly, handling, storage, use or disposal of
the product.
The information in this manual is provided without any warranties, expressed or implied. Be very
careful when handling the 3D printer. It is an electrical device with moving and heated parts.
Placement and Basic Use
Make sure that the printer is located and operated in a safe place to avoid potential risks.
This device is intended for indoor use only. Do not expose the device to water or snow. Contact
with water and other liquids may lead to damage to the electronics, short circuits, and other
types of damage. Always operate the printer in a dry environment.
Place the printer in a safe dry place on a horizontal and stable surface - e.g., a work table.
Around the printer should be at least 30 cm of space. If there are obstacles close to the
printer, it may affect its operation or cause excessive wear of the textile cable sleeves or even
the cables themselves. Worn cables can pose a risk (electric shock, fire).
Make sure that none of the exhausts/fans is blocked. The printer has a built-in fan speed
monitoring, but in some cases (incorrect assembly, damage to components, unofficial
firmware) the monitoring may not work correctly. Insufficient cooling can lead to overheating
and serious damage to the printer (risk of damage to electronics, fire).
Make sure that the printer is placed so that it cannot be toppled over or dropped to the
ground. If the printer has suffered physical damage, do not use it - damaged parts of the
printer may pose a safety risk.
The power cable must be placed so that it cannot be tripped over, stepped on, or otherwise
damaged. Place the printer on a stable, solid surface (e.g., a work desk). If the printer is
damaged, stop using the device, turn it off immediately and contact us for assistance.
Damaged cables pose a safety risk - there is a risk of electric shock or fire.
Do not leave the printer switched on without supervision! The printer has temperature
monitoring and a number of smart features for increased safety, but in the case of use
contrary to the instructions in this manual or failure of components, there is a risk of fire.
Never place anything into the printer under the heatbed - the heatbed is a moving part and
could crash into objects underneath it!

9
Electrical Safety
The printer should only be powered through a standard 230 VAC, 50 Hz or 110 VAC, 60 Hz
outlet. Never use alternative power sources as they can cause problems or damage the printer.
Do not use the printer if the power cord is damaged in any way – damaged cords can lead to
electric shock.
When disconnecting the power cord from the outlet, pull the plug, not the cord, to reduce the
risk of damaging the plug or outlet.
Never disassemble the power supply of the printer as it contains no parts that can be repaired
by an untrained worker. Always take the printer to a qualified service technician for repairs.
Improper interventions in the power supply may lead to damage to the printer and an
increased risk of electric shock.
The device is disconnected from the power supply by pulling out the plug. The electrical outlet
must be easily accessible.
The printer is equipped with a replaceable fuse located in the fuse holder near the connecting
connector of the power source and it protects the entire printer. Before replacing the fuse, switch
off the printer and disconnect the power supply by pulling out the power cord from the outlet.
Push the fuse holder out using a flat screwdriver, remove the fuse and insert a new one. Push the
fuse holder back in place. Always make sure the new fuse has the same value as stated on the
label. If the fuse blows repeatedly, contact the tech support.
Mechanical Risk
Moving mechanical parts of the printer can cause injury.
Never interfere with the inner components of the printer when it is connected to the power
supply or running – there is a risk of injury from mechanical parts or electric shock.
Prevent children from manipulating the printer without the supervision of an adult – even
when the printer is not printing.
Burn Risk
Do not touch heated parts of the printer – heatbed, print plate, and parts of the printhead.
There is a risk of burns.
Warning! During printing, parts of the printhead and the print plate can heat up to very high
temperatures! Do not touch them until the printing ends and the printer cools down –
otherwise, you may get burned.

10
Proper Use of Double-Sided Print Sheets
Each type of print sheet requires slightly different maintenance. Improper handling and use can
lead to damage to the print sheet, heatbed or other parts of the printer. Print sheets are
consumable and subject to wear.
The surface of the textured and satin print sheet must not be cleaned with acetone!
Please refer to the Flexible Print Sheets chapter for maintenance instructions.
To degrease the sheet’s surface, use highly concentrated isopropyl alcohol (90% or higher).
Do not use products that contain IPA as one of the components (e.g. hand sanitizers) - these
products usually contain other additives that may negatively affect the properties of the
printing plate.
Do not wash under running water - the sheet may start to rust.
Do not remove the PEI film from the plate surface.
If the sheet is dirty, clean its surface with an isopropyl alcohol-dampened wipe before you start
printing.
Printing sheets are held in place on the heated bed with strong magnets - be careful when
placing the sheet on the heatbed to avoid injury.
Do not slide the sheet when it is attached to the heatbed with magnets - the friction may lead
to damaging the heatbed.
Working with Filaments
When handled correctly, working with filaments is straightforward and safe. Please read the
following recommendations.
Always use the recommended temperatures for the selected material.
Beware of molten plastic - it can cause burns! If there is molten plastic stuck in the nozzle, do
not remove it by hand - use pliers or other tools.
Some materials may emit a strong odor when printing - regularly ventilate the room.
Handle the filament according to the instructions on the following pages of the manual.
Always make sure that the end of the filament is properly secured (either in the extruder or in
the spool). If you accidentally release the end of the filament, it may easily tangle up and create
knots.

11
1. Introduction
Thank you for purchasing the Original Prusa MK4 3D printer from Prusa Research! Your support
allows us to invest in further development of 3D printers and other 3D printing products, such as
PrusaSlicer, our amazing slicing software. We also have our own in-house line of resins and
filaments (Prusament), operate Printables.com and partake in many other awesome activities -
check it out on our Blog at blog.prusa3d.com!
The MK4 is a collective effort of many talented developers, teams and individuals. It evolved over
the course of several years. We kept all the proven features from the award-winning Original
Prusa i3 MK3: simple operation, easy maintenance, heatbed with double-sided print sheets,
filament sensor, high-quality PSU, long-term support, upgrade packages, optional add-ons and
many more. Still, roughly 90 percent of all parts have been changed. Here are some of the
things making their debut in the MK-series product line.
1.1. Nextruder
Nextruder is our next-generation extruder built around a solid aluminum heatsink and an all-
metal hotend. Featuring the Loadcell tech, the Nextruder can deliver an absolutely pristine first
layer every time, no matter what material or print sheet you use. Compared to the PINDA sensor
in older models, the analog Loadcell sensor is much more precise. At the beginning of each print,
the Nextruder uses the nozzle to tap the sheet in a grid pattern and measures the tension
inside the extruder to quickly create a virtual heightmap of the print sheet with impeccable
accuracy. The printer also measures only the actual print area where the object will be printed.
The Nextruder also contains an electronics breakout board with connectors for all parts of the
extruder. This means that all fans, thermistors and other parts are connected to the board.
Then, only a single cable bundle leads from the Nextruder electronics to the main motherboard
(xBuddy). This makes replacing parts of the extruder much faster.
The Nextruder is lighter than the MK3 extruder and its center of gravity is closer to the X-axis
rods, improving the overall performance. Inside the Nextruder, there is a brand-new planetary
gearbox connected to a large drive gear that pushes the filament into the nozzle.

12
1.2. Quick-Swap Nozzles
Changing nozzles is super quick with our new thumbscrew system. Simply flip open the side fan
(print fan) to reveal two thumbscrews. Unscrew them to release the nozzle assembly. Then
disconnect two cables from the LoveBoard in the Nextruder and pull out the entire hotend
assembly (nozzle and heater block) and swap it with a different one. Or simply remove only the
nozzle and replace it with a different diameter model.
1.3. 32-bit Connected Architecture
The MK3's 8-bit EINSY motherboard was replaced by a brand new 32-bit xBuddy board
featuring improved parameters, even better safety features, additional connectors and support
for color LCD touchscreen among other things. The MK4 has a built-in ethernet port and a port
for an optional Wi-Fi module (ESP-01), which opens new remote management options with
Prusa Connect (connect.prusa3d.com). The xBuddy board comes with highly advanced hardware-
based safety features, such as overcurrent protection, overheat detection, dual voltage
monitoring, loose heatbed connector detection and many more. For example, the xBuddy can
measure the consumption (by measuring the current) of the heater block and heatbed, and
compare them with the temperatures reported by thermistors.

13
2. Unpacking and Package Contents
If you purchased the printer as a fully assembled model, simply remove the top foam inlay from
the box. Find a good place for the MK4. You need at least 520×520mm of space for the printer
to operate. Keep in mind that the heatbed moves back and forth during printing and the cables
must not hit a wall when the heatbed is in the rearmost position. Grab the top part of the metal
frame and lift the printer from the box - see the chapter below: How to Move the Printer.
If you purchased the assembly kit, head on over to help.prusa3d.com to learn how to assemble
it!
2.1. How to Move the Printer
If you want to move the Original Prusa MK4 printer, use the recommended method - grab the top
of the printer frame and lift the printer. Never lift the printer by the cables, filament holders or X-
axis.

14
2.2. Contents of the Package and Accessories
Your Original Prusa MK4 printer package includes:
Documentation
USB drive with sample prints (G-codes)
MK4 Toolset
Uni-wrench
13-16 wrench
Philips screwdriver
Nose pliers
Allen and torx keys
Alcohol-saturated wipe (for initial calibration), acupuncture needle
Double-sided Smooth PEI Print Sheet
1 kg spool of Prusament filament (only with Assembled printer)
Spoolholder
Spare parts
Prusa lubricant for bearings
A pack of Haribo gummy bears
These are the basic tools necessary for assembly and basic maintenance. We recommend
purchasing a few extra accessories, such as:
Cutting pliers for cutting the end of filaments or removing supports from printed objects
Isopropyl alcohol (90% or more) for cleaning the print sheet
Paper wipes for cleaning the print sheet
Plastic spatula for removing plastic from the print sheet - you can actually print one!
The latest version of this handbook can be found at prusa3d.com/drivers in PDF format.
If you encounter any problems while using the printer, do not hesitate to contact us at
[email protected]. We will be happy to answer your questions or hear your ideas for
improvement. You can also visit our Knowledge Base at help.prusa3d.com or the user discussion
forums at forum.prusa3d.com.

15
3. Original Prusa MK4 Overview and Glossary
Filament spool - The MK4 is compatible with 1.75mm filaments.1.
Frame2.
Z-Axis - vertical, consists of threaded and smooth rods, moves the Nextruder up and down.3.
Nextruder - Our new next-generation extruder with a planetary gearbox and Loadcell sensor.4.
X-axis stepper motor - moves the Nextruder left and right.5.
Electronics box - housing for the xBuddy board. Ethernet and Wi-Fi ports are accessible from6. the rear.
Z-axis stepper motor - one of two total. Z-axis motors move the Nextruder up and down.7.
LCD - used for control and configuration of the printer.8.
Spoolholder9.
X-axis - a general name for the entire horizontal assembly consisting of two smooth rods, an10. X-axis motor, a belt and plastic parts. The Nextruder moves along the X-axis from left to right.
Power Supply Unit11.
Print sheet - easy to maintain, held in place with strong magnets embedded in the heatbed.12.
Heatbed - proven Prusa MK52 heatbed.13.
USB port and USB drive - use the USB drive to print G-Codes (print files) and flash firmware.14.
Rotary knob - main control device with the Reset button directly below it.15.

16
Filament insertion point (from the top) - the MK4 is compatible with 1.75mm filaments.1.
Idler lock (swivel) - flip upwards to unlock the idler door.2.
Idler - maintains pressure on the filament strand as it is moved further into the extruder by the3. extruder gear.
Planetary gearbox and extruder motor.4.
Print fan (on the side) - the fan mount is on a hinge and held in place by magnets. You can flip5. it open to access the thumbscrews.
Thumbscrews - secure the nozzle in place.6.
Fan shroud - directs the air from the print fan towards the printed object.7.
Electronics cover - covers the break-out board.8.
Idler screws - these screws are used to adjust the pressure of the idler.9.
Heatsink fan - cools the aluminum heatsink behind it.10.
Heater block - contains heater core and heater thermistor.11.
Nozzle - by default, a 0.4mm nozzle is installed.12.
DO NOT remove the cover of the gearbox under any circumstances. The gearbox is aligned and
calibrated from the factory. Removing the housing could easily cause the gearbox to dislocate.

17
3.1. Connecting and Disconnecting the Power Cable
Always pull the connector, do not pull on the cable itself! Incorrect handling can lead to damage
to the connector or cable.
The power supply port is located on the rear side of the printer. Before you plug or unplug the
cable, turn the printer off using the physical switch on the power supply unit next to the power
supply port. See the picture below to learn how to correctly disconnect the power plug from the
power supply.
3.2. Error Screens
If the printer encounters a critical error, an error screen will be displayed with a description of
the error. The information on the screen is intended to facilitate easy identification, diagnosis and
resolution of the error. Pay special attention to the text on the screen. Most error messages are
supplemented with a QR code - scanning it (e.g. using a camera on a mobile phone) will take you
to a relevant article with instructions on how to proceed.
This is a sample QR error code serving as an example of an error message.

18
4. Your First Print
To get your printer up and running, please pay attention to the information in the following
chapters. We will go through the basics together - you’ll be printing in no time!
In this chapter you will learn how to:
Control the printer
Prepare the print sheet for the first print
Perform initial calibration
Insert filament
Start the first print
Remove the print
Troubleshoot basic issues
Update the firmware
4.1. Basic controls
All configuration steps and overall control of the printer are done with one control element - a
rotary knob. Rotate it to select items on the screen and press it to confirm your selection. The
reset button is located under the rotary knob. Pressing the reset button is the same as quickly
turning the printer off and on again. It is useful in cases where it is necessary to immediately stop
an action that the printer is currently performing.

19
4.2. Selftest Calibration (Wizard)
When you first power on the Original Prusa MK4, the Selftest calibration wizard will start. The
wizard will walk you through the initial calibration and all necessary tests to start printing.
Completing the entire checklist is mandatory. But don't worry, it's gonna be super easy, barely an
inconvenience!
Do not select Continue yet, let's make sure your printer is ready for the Selftest. We'll return to this
screen in a minute.
The purpose of the calibration is to check whether your printer is in a good shape. It's a one-
time process that doesn't need to be repeated before every print. Run it again if you encounter
issues with your printer (more on that in the advanced sections of this handbook).
The Wizard will provide you with text descriptions and illustrations of the individual steps. It
is designed to make the process as automated and understandable as possible. For clarity, some
actions are further described in the following chapters. You can also start the Selftest manually
using the LCD menu - Control - Run Full Selftest. You need to install the print sheet onto the
heatbed to successfully pass the Selftest.
So, let's start with placing the print sheet that came with your MK4 onto the heatbed - turn to
the next page.

20
4.3. Preparing Flexible Print Sheets
Make sure there is no debris on the heatbed before you install the print sheet. It could either
throw off the first layer calibration or possibly even damage your printer.
Do not drag the print sheet while it's attached with magnets, you could scratch and damage the
heatbed. If you need to readjust the print sheet, always lift it up by grabbing the front two
corners, adjust its position and then place it back down.
The Original Prusa MK4 comes standard with a double-sided smooth PEI print sheet. If you have
a different type, we recommend that you carefully study how to properly treat the surface in the
Regular Maintenance chapter.
There are high-temperature magnets embedded into the heatbed that hold the removable flexible
print sheets in place. On the back of the heatbed, you will find two pins that fit exactly into the
cutout of the print sheet. Before installing the sheet onto the heatbed, make sure that it is
perfectly clean. Never print directly on the heated bed!
Attach the sheet by first aligning the rear cutout with the locking pins on the back of the
heated bed (marked in orange in the picture above). Hold the sheet by the front two corners and
slowly lay it down onto the heated bed - watch your fingers!
For your first print, it is enough to wipe the bed using the supplied cleaning wipes soaked with
isopropyl alcohol. You can do it now, but make sure not to touch the surface of the sheet
afterward.
Now, let's return to the Selftest wizard. Select "Continue" on the screen and start the
calibration.