Prusa Research PRUSA MMU3 User manual

3D PRINTING
HANDBOOK
FOR THE ORIGINAL PRUSA MMU3
ORIGINAL INSTRUCTIONS
ENG

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Original Prusa MMU3: Official Instructions
Version 1.00 - June 20th, 2023
This handbook covers only the Original Prusa MMU3 for the Original Prusa i3 MK3S+ 3D
printer. Instructions for Original Prusa MK4 are not included. The latest version of this
handbook can always be found at prusa3d.com/drivers.
Quick Guide to the First Print
Download and install Drivers & Apps from www.prusa3d.com/drivers and update printer1. firmware with PrusaSlicer if the MK3S+ or MMU3 firmware is out-of-date.
Place filament spool holders behind the printer, the filament buffer next to the printer and2. pull filament strands through the filament buffer using the slide-out cassettes.
Run the following calibrations: IR filament sensor, Z-Axis and First Layer.3.
Print your first test object!4.
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 MMU3 assembly instructions.
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.

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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. Before You Begin 13 ..................................................................................................................................................
1.1. Placement and Setup 13 ...............................................................................................................................
1.2. Flashing the Firmware 14 .............................................................................................................................
1.2.1. Flashing firmware on Windows 14 ...............................................................................................
1.2.2. Flashing the firmware on MacOS and Linux 16 ...................................................................
1.2.3. Initialization procedure 16 ...............................................................................................................
2. Filament Operations (Loading, Unloading and more) 16 .....................................................................
2.1. Preparing the filament 17 .............................................................................................................................
2.2. Inserting filament through the buffer 17 ...............................................................................................
2.3. Loading all five filaments at once 19 ......................................................................................................
2.4. Loading one of the filaments using the LCD Menu 19 ..................................................................
2.5. Loading one of the filaments using the MMU control buttons 20 ...........................................
2.6. Ejecting filament 20 ......................................................................................................................................
2.7. Load to the nozzle / Unload 21 .................................................................................................................
2.8. FINDA explained 21 .......................................................................................................................................
3. Calibration 22 ..............................................................................................................................................................
3.1. IR filament sensor calibration 22 ..............................................................................................................
3.2. Calibrate the Z-axis 24 .................................................................................................................................
3.3. First Layer Calibration 24 ............................................................................................................................
4. First Print 26 .................................................................................................................................................................
5. Printing in Multi-Material Mode 27 ..................................................................................................................
5.1. PrusaSlicer - Initial Setup and General Workflow 27 .....................................................................
5.1.1. Setting up Colors 30 ..........................................................................................................................
5.1.2. Coloring an Object 33 .......................................................................................................................
5.2. Smart wipe tower 35 .....................................................................................................................................
5.2.1. Wipe tower placement 35 ...............................................................................................................
5.2.2. Purging volumes 36 ..........................................................................................................................
5.3. Wipe to infill 37 ................................................................................................................................................
5.4. Wipe object 38 .................................................................................................................................................
5.5. Supported Materials 39 ...............................................................................................................................
5.5.1. Soluble Supports 39 ..........................................................................................................................
5.5.2. Soluble support interface only 40 ..............................................................................................
5.5.3. Completely soluble supports 41 ..................................................................................................
5.5.4. Removing Soluble Supports 41 ...................................................................................................
5.6. Slicing and Exporting 42 .............................................................................................................................
6. Printing in Single Mode 42 ...................................................................................................................................
7. Handling 43 ...................................................................................................................................................................
7.1. Mounting/Unmounting the MMU3 unit 43 .........................................................................................
7.2. Transporting the printer 43 ........................................................................................................................
8. Menu structure 44 ....................................................................................................................................................
8.1. Explanation of Advanced Features 47 ....................................................................................................
8.1.1. Preload to MMU 47 .............................................................................................................................
8.1.2. SpoolJoin 47 ..........................................................................................................................................
8.1.3. Loading test 47 ....................................................................................................................................
8.1.4. HBed on Load 47 .................................................................................................................................
8.1.5. Power panic support 47 ...................................................................................................................
9. Troubleshooting 48 ..................................................................................................................................................
9.1. Selector Cannot Home / Move Error 50 ..............................................................................................

9.2. Idler Cannot Move / Home 50 ..................................................................................................................
9.3. Pulley Cannot Move Error 50 ....................................................................................................................
9.4. Filament not extruded during the print (missing layers) 51 .........................................................
9.5. FINDA Filament Stuck Error 51 ...............................................................................................................
9.6. FINDA Didn't Trigger / Inspect FINDA 51 ..........................................................................................
9.7. Error Descriptions Online 52 .....................................................................................................................
9.8. Different filament tip shapes after the unload 52 ............................................................................
9.9. Pulleys covered in filament dust 52 ........................................................................................................
9.10. Can not update the MMU3 firmware 53 ...........................................................................................
9.11. Crash detection 53 ........................................................................................................................................

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Safety symbols and their meaning
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.
Unprotected moving mechanical parts can cause injuries, please take extra care.
This device is composed of components that must be disposed of in accordance with the
Directive on Waste Electrical and Electronic Equipment.

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Product Information
Name: Original Prusa MMU3
Manufacturer: Prusa Research a.s., Partyzánská 188/7a, Holešovice, 170 00,
Prague, Czech Republic
Contacts: Phone: [phone], e-mail: [email protected]
Usage: indoor use only
Power supply: 24 VDC, 2 A max., provided by the 3D printer
Operating temperature range: 18 °C - 38 °C
Maximum air humidity: 85%, non-condensing
Product dimensions:
Width: 204 mm
Depth: 120 mm
Height: 144 mm
Supported filament diameter: 1.75 mm
Weight (with / without
packaging) 3700 g / 900 g
The product serial number can be found on the type label located on the device and on the outer
packaging.
This device is intended for use in indoor environments only where it is protected against external
influences.
Warranty
The Original Prusa MMU3 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 MMU3 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 Original Prusa MMU3 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.
Make sure that the printer with the Original Prusa MMU3 is placed so that it cannot be
toppled over or dropped to the ground. If the printer or the device has suffered physical
damage, do not use it - damaged parts of the printer may pose a safety risk.
Do not leave the printer with the Original Prusa MMU3 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 body of the Original Prusa MMU3. It contains rotating and
moving mechanical parts and any foreign objects might damage it.
Electrical Safety
The Original Prusa MMU3 should only be powered with the original power cable that comes
with the product. Do not use any other power cables or power units, custom electronics or
anything of this nature to power the Original Prusa MMU3.
Do not use the Original Prusa MMU3 if the power cord is damaged in any way – damaged
cords can lead to electric shock.
When disconnecting the power cord from the Original Prusa MMU3, unlock the latch and then
pull the plug. Do not pull the cord, otherwise you might damage it.
Never disassemble the electrical parts of the device. Always take the printer to a qualified
service technician for repairs. Improper interventions may lead to damage to the device
The device is disconnected from the power supply by pulling out the plug out of the printer.
The electrical outlet must be easily accessible.

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Mechanical Risk
Moving mechanical parts of the device 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.
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 in the handbook for your 3D printer 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.

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About the product
Original Prusa MMU3 (Multi-Material Upgrade 3) is the latest revision of our unique multi-
material printing solution. It is compatible with the Original Prusa i3 MK3S+ and Original Prusa
MK4. Compared to the previous MMU2 unit, the new one features reworked hardware and brand
new firmware built from the ground up. The MMU3 comes with full two-way communication
between the printer and the unit, which enables much more detailed and comprehensive controls.
The MMU3 gives you the option to load up to five filaments at the same time, so you can print
even more detailed and intricate objects. With smart features, such as Wipe to Infill and Wipe
Object, you can save a lot of waste and time when printing. Or, you can combine more materials -
such as PCCF for the object itself and another (cheaper) material to print the supports, lowering
the total costs.
To unlock the maximum potential of your printer with the MMU3, use our latest PrusaSlicer
slicing software. Offering a multitude of unique features, PrusaSlicer is the go-to solution for
single and multi-material printing.
In case of an issue, the printer receives information from the unit and displays a full description of
the situation, and also suggests solutions to resolve it in case it's not possible to resolve the
situation automatically. Detailed troubleshooting guides can be found at help.prusa3d.com.

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Original Prusa MMU3 Description
See the picture below to learn the official names for each MMU3 part. We will be referring to
these names in our guide.
Idler motor - rotates the idler.1.
Idler - contains five pulleys. By rotating the idler, a single pulley gets in direct contact with the2. filament and applies pressure on it. Then, the pulley motor can push the filament forward into
the selector.
Left hardware button - moves the selector left.3.
Middle hardware button - preloads filament into the selected position.4.
Right hardware button - moves the selector right.5.
LED indicators - indicate the current status of the MMU (selected position, errors, etc.)6.
SuperFINDA (or FINDA for short) - MMU3 filament sensor built into the selector. 7.
Selector - selects a filament slot by moving to the requested position. Filament is then pushed8. through the Selector into the nozzle by the Pulley Motor.
Festo fitting - there are two Festo fittings on the front PTFE tube, the other one is mounted to9. the top of the extruder

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Reset button - triggers reset of the MMU3 unit only1.
MicroUSB port - for flashing MMU3 firmware via PC2.
Pulley motor - rotates the pulleys that move the filament inside the MMU3 unit3.
Selector motor - moves the Selector left and right4.
How the MMU3 Works
The MMU3 is designed to be pre-loaded with up to five filaments. In the MMU3 unit, all loaded
filaments are placed across the five grooved drive gears on the pulley axis. With the idler
disengaged and the selector in the right-most position (also called "service position"), the pulley
axis can rotate freely without moving the pre-loaded filaments.
When a filament is ready to be fed into the printer's nozzle, the selector moves to the appropriate
position, and the idler barrel rotates, causing a pulley to apply pressure to the selected filament. As
the pulley axis begins to rotate, the filament is grabbed and pushed by the drive gear. The motor's
rotation propels the filament forward, passing through the selector and entering the extruder.
When a material change is necessary, the printer unloads the filament from both the nozzle and
the extruder, aligning it with the other filaments inside the MMU3. Then, the selector moves to a
different position, and the idler rotates once again to apply pressure on a new filament. All of these
processes are automated, and information about filament changes is stored within the print file.

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1. Before You Begin
This handbook picks up where the Assembly Manual ends, and explains the basic usage of the
Original Prusa MMU3. It is absolutely essential to assemble, attach and initialize the MMU3
unit exactly as described in the assembly manual.
For clarity, reference and better overview, some of the steps from the Assembly Manual are
repeated in this handbook.
1.1. Placement and Setup
First of all, let's make sure your Original Prusa i3 MK3S+ with the MMU3 is placed as
recommended - with the filament buffer next to the printer and spoolholders spread out in a fan-
like formation behind the printer.
The placement described above is ideal as an initial setup. There are other possible layouts that
you can try (e.g., mounting the spools on a wall or a rack), so feel free to experiment. But
remember, that excessive bending of PTFE tubes causes high resistance when loading
filaments, which may result in various issues during printing.
Before you start printing, you need to make sure that you have the latest firmware so that your
printer can communicate with the unit. Let's do it now.

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1.2. Flashing the Firmware
Before you start using the MMU3, the printer’s firmware should be updated, otherwise, the
printer won’t communicate with the new unit. Always use the latest available firmware (v3.13 or
newer) to ensure compatibility with the MMU3 and take advantage of the latest (safety) features
and other improvements.
The MMU3 motherboard can be also updated with new firmware, which comes as a separate
file. Please keep in mind that there are slightly different flashing procedures for each board and
that firmware files for the printer and the MMU3 can be released independently. Drivers, apps and
firmware files can be downloaded from www.prusa3d.com/drivers.
WARNING: Do not disconnect the printer during the flashing process!
MAKE SURE YOU HAVE THE CORRECT FIRMWARE FILE FOR THE DEVICE YOU WOULD
LIKE TO UPDATE!
1.2.1. Flashing firmware on Windows
You can find information about currently installed firmware in LCD Menu - Support. Use the Knob
to scroll through the list and look for "Firmware" and "MMU Connected" - you'll find version info
under these items.
To flash the firmware:
Go to www.prusa3d.com/drivers and download the correct firmware for your printer and/or1. MMU3 unit. Please note that there is a different firmware for each of our printers and also a
different type of firmware for the MMU3.
Download the latest Drivers & Apps package from the same page and install it. Make sure2. that PrusaSlicer and Drivers are selected in the installation wizard.
Turn on the printer and wait for the initialization to complete.3.
Connect the device to your PC using a USB cable. The type of USB cable and the port4. depends on which type of firmware you want to flash.
TO FLASH PRINTER FIRMWARE: Use the standard procedure as described in the 3D printing
handbook that came with your printer. Connect the printer mainboard (RAMBo) to your PC using
a square-shaped USB-B 2.0 cable.

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Start PrusaSlicer and select Configuration -> Flash Printer Firmware (blue arrow).1.
A new window will appear. Your printer should be detected in the ‘Serial Port’ box. Open the2. drop-down menu in case it's not automatically selected (green arrow).
Click Browse to select the downloaded firmware file (orange arrow).3.
Press Flash! and wait for the process to finish (yellow arrow).4.
Once the flashing process is finished, you can disconnect the printer from your PC.5.
TO FLASH MMU3 UNIT FIRMWARE: Use a micro USB cable to connect the MMU3 unit to your
PC and follow the same procedure.
Start PrusaSlicer and select Configuration -> Flash Printer Firmware.1.
A new window will appear. Your MMU3 should be detected in the ‘Serial Port’ box. Open the2. drop-down menu in case it's not automatically selected.
Click Browse to select the downloaded firmware file. Select the MMU3 firmware, not the3.
MK3S+ 3D printer firmware!!
Press Flash! and wait for the process to finish.4.
Once the flashing process is finished, you can disconnect the printer from your PC.5.
If the flashing process fails, simply restart the printer and try again. There is an 8-second window
during the start-up when the bootloader (flashing) mode is active. You should start flashing the
device during this 8-second window.
Do not have both the printer and the MMU3 connected with USB cables at the same time to
prevent potential issues with serial ports.
MMU3 unit not recognized? it’s possible that your antivirus software has prevented the drivers
from installing. Try installing them manually from the destination directory - C:\Program
Files\Prusa3D\Drivers by default. Or try a different USB port or a micro USB cable.

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1.2.2. Flashing the firmware on MacOS and Linux
To flash the firmware on MacOS or Linux, please download the latest version of PrusaSlicer for
your system, then download the firmware files and follow the procedure described above.
Downloading and installing USB drivers is not necessary.
Firmware files for the lineup of our printers and devices are updated regularly. To ensure the
best possible experience when working with the printer and the MMU3, it is necessary to
always use the latest firmware.
1.2.3. Initialization procedure
The MMU3 unit is turned on simultaneously with the printer. After that, the homing procedure of
the idler body (extruder stepper) is started. During homing procedures, a repeated clicking sound
can be heard - this is a part of the procedure.
Please keep in mind that during the first few seconds, the MMU unit is in bootloader mode -
waiting for a possible firmware flashing procedure. Once this is done, the selector will move left
and right and the idler will rotate. After that the printer is ready to be used.
Go to the LCD Menu - Settings - MMU and make sure this option is set to "On". If it is set to
"Off", change it to "On" and then restart the printer using the rear power switch. This ensures that
the MMU3 unit is correctly recognized.
You can check whether the printer communicates with the MMU3 unit by going into LCD Menu -
Support and looking for "MMU connected" item.
2. Filament Operations (Loading, Unloading and more)
You can skip this chapter and go directly to the First Print chapter, if you already went through
this process in the Assembly Manual, filaments are already preloaded to MMU and you
performed the necessary calibrations (IR sensor, Z-Axis and First layer).
Now that the MMU is connected to your Original Prusa i3 MK3S+ and the firmware is updated,
you can start loading filament.

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You don’t need to preheat the nozzle as filament loading pushes the filament only to the MMU3
unit. Insertion of the filament into the extruder is done automatically during print.
2.1. Preparing the filament
Just like with the stock printer, it's necessary to make sure that the filament you are about to load
is correctly prepared - the tip is sharp, and there are no bumps or bends which could negatively
affect the movement of the filament strand. Use sharp pliers to cut the tip of the filament.
See the picture below for reference.
Most filaments absorb moisture from the air, so even if you printed from a certain filament and
everything was fine, letting it sit on a table for several days may degrade its quality, which then
leads to, i.e. stringing tips.
2.2. Inserting filament through the buffer
Make sure the filament buffer is correctly attached to the frame of the printer.
If you want to load all five materials now, go to LCD Menu - Preload to MMU - Load All. This will
activate the filament loading procedure. The selector will move to the first position, the idler will
engage and the pulley motor will start turning. This procedure will run until all five filaments are
correctly loaded, so you don't have to worry about timeouts.
Alternatively, if you want to load fewer filaments, go to LCD Menu - Preload to MMU and choose
individual positions (1/2/3/4/5) for each filament you want to load. Once the pulley motor starts
turning, you can start loading filaments.

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Pull the first cassette out of the buffer. All cassettes are numbered so you can easily tell which1. cassette corresponds to which filament slot in the MMU3.
Insert the tip of the filament into the bottom PTFE tube attached to the spoolholder.2.
Keep pushing the filament into the PTFE tube until it appears in the cassette you pulled out.3.
Take the tip of the filament and insert it into the other PTFE tube leading to the MMU unit.4.
To make things easier, do not return the cassette back into the buffer at this point. Push the5. filament through the PTFE tube towards the MMU3 unit until the plastic strand is caught by
the drive gear - see the rear transparent PTFE tubes to easily tell where the strand of filament
currently is. You can release the filament now and wait for the MMU unit to finish the
preloading procedure
Push the cassette back into the buffer and repeat the procedure with the other filaments (if6. applicable).

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2.3. Loading all five filaments at once
Go to LCD Menu - Preload to MMU - Load All.1.
The selector will move to the first position, the first LED will start blinking green.2.
Push the filament to the first PTFE tube until it’s caught by the drive gear.3.
The filament will be pushed until it’s detected by the FINDA, then it will be retracted from the4. selector, ready to be extruded when needed.
The selector will move to the second position.5.
Repeat the process for the remaining 4 filaments.6.
The loading procedure for each position runs indefinitely until filament is caught by the FINDA
sensor. This way, you can keep this procedure running and insert filaments one by one as
described in the previous chapter.
2.4. Loading one of the filaments using the LCD Menu
Go to LCD Menu - Preload to MMU - Load filament 1/2/3/4/5.1.
The selector will move to the selected position, the corresponding LED will start blinking2. green.
Insert the filament into the correct PTFE tube and push it until it’s caught by the drive gear.3.
The filament will be pushed until it’s detected by the FINDA, then it will be retracted from the4. selector, ready to be extruded when needed.
The LED will turn off.5.

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2.5. Loading one of the filaments using the MMU control buttons
Using the left and right control buttons, move the selector to the position corresponding with1. the filament number you’d like to load.
Insert the filament inside the white PTFE tube and continue pushing it until it’s not possible to2. push it any further.
Press and hold the middle control button for a few seconds.3.
The corresponding LED indicator will start blinking green.4.
Push the filament a little bit further into the white PTFE tube until it’s caught by the extruder.5.
The LED indicator should turn green after a short while, signaling a successful filament load.6.
To unload pre-loaded filament simply pull the filament string from the white PTFE tube
manually - move the selector away from the slot using the hardware buttons if it is engaged. If the
filament is loaded into the nozzle, you need to go to LCD Menu - Unload Filament first.
If you want to verify the proper load of all five filaments before print, select LCD Menu - Preload
to MMU - Load all. The MMU3 will quickly try loading and unloading all 5 filaments one after
another without any user interaction. Green LED should signal the success of load after each
position.
2.6. Ejecting filament
In the situation when you're about to finish a filament spool, the end of the filament may end up
halfway in one of the loading tubes. If it's too short, it's not possible to pull the filament strand
from the back. Instead, you can use the front ejection menu action.
Found in LCD Menu - Eject Filament - Eject Filament 1/2/3/4/5. It’s advised to run this
procedure after you use up filament scraps through the automatic depletion function (LCD Menu
- Settings - SpoolJoin [on/off]). It allows you to remove the last remaining piece of filament from
the loading tubes after a filament spool is completely used up.
Ejecting during the print:
Pause print via the LCD menu.1.
Select the Eject filament option and choose which filament you want to remove.2.
Then, the selector moves to the side and the filament string is ejected forward (through the3. MMU3 unit).
Remove the rest of filament string and press the knob.4.
Select the Load filament option and insert a new filament string as usual.5.
Resume the print process.6.
The ends of the filament string must be straight in order to perform the ejecting process
correctly.