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10B. MK3S+ Setup and Calibration

10B. MK3S+ Setup and Calibration

10B. MK3S+ Setup and Calibration
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Last updated 6 days ago
10B. MK3S+ Setup and Calibration
 Difficulty
Very difficult
 Steps
31
 Available languages
CSPLDEESITFR
Tools necessary for this chapter
Tools necessary for this chapter
Please prepare tools for this chapter:
Unikey for tightening up the Festo fittings.
1.5mm Allen key for Filament sensor calibration
2.5mm Allen key for M3 screws
Phillips screwdriver for power cable terminals
Attaching the MMU unit (part 1)
Attaching the MMU unit (part 1)
Attaching the MMU unit (part 1)
Attaching the MMU unit (part 1)
The MMU3 unit should be placed in the middle of the top part of the printer's aluminum frame.
Place the MMU3 unit onto the frame.

Attach it just by the top hooks.
Look from behind, there are "clamps", which will be used to lock the unit to the frame in the next step.
Attaching the MMU unit (part 2)
Attaching the MMU unit (part 2)
Attaching the MMU unit (part 2)
Make sure the unit is in the middle of the frame. Once we engage the clamps, it won't move left and right as easily anymore.
Press the back part of the MMU3 unit downwards slightly, until the clamps lock to the frame.
Check that both bottom clamps on the unit are fully engaged.
If you need to remove the unit from the frame, simply lift the back part up to disengage the clamps.
Attaching the cable bundle
Attaching the cable bundle
Attaching the cable bundle
Let’s move onto the electronics box side of the extruder cable bundle.
Tighten up the sleeve around the cable bundle. Hold it tight before you fix it in place with the clip and the screws. The textile sleeve should be held by the cable clip
Fix the cable bundle in place by tightening the two M3x10 screws holding the Extruder-cable-clip. Make sure no cable is getting pinched!
For easier cable-management inside the electronics box, attach the extruder cable bundle to the hooks on the inside of the Einsy-base with two zip-ties in the marked positions.
Guiding the MMU cable
Guiding the MMU cable
Guiding the MMU cable
Now, we will guide the cables from the MMU unit into the printer.
Make sure the printer is turned OFF and unplugged from the wall outlet. Do not ever connect or disconnect the MMU unit while the printer is ON.
Guide the cable bundle from the MMU unit towards the printer’s electronics. The cable should be placed just next to the printer's frame.
You can fix the cable to the MMU3 holder using a zip-tie in marked location. Make sure it points to the side - not down. Otherwise, it might interfere with the extruder cable while printing.
Guide the cable towards the electronics box.
MK3S+ Trimming the electronics box door
MK3S+ Trimming the electronics box door
MK3S+ Trimming the electronics box door
MK3S+ Trimming the electronics box door
WARNING: We need to cut part of the plastic on the electronics box door to make some room for the MMU cable. Make sure you wear protective eyewear!
If you’re upgrading from the MMU2S to MMU3 and your door has been trimmed already in the past, you can skip this step.
Release and remove the M3x10 screw in the upper hinge. Remove the door together with the hinge by pulling it up.
Using pliers, carefully cut the inner corner of the door. The MMU cable bundle will need some more clearance in the marked location.
Comparison between the trimmed door (left) and its original shape (right).
MK3S+ Trimmed electronics door installation
MK3S+ Trimmed electronics door installation
MK3S+ Trimmed electronics door installation
Re-attach the door back onto the bottom hinge.
Make sure the top hinge is in place.
Attach the top hinge to the printers frame using the M3x10 screw.
Make sure there is enough clearance for the MMU3 cable when you close the door.
The cable should be held by the door but must not be squished too much. Otherwise, you risk damaging the cable!
MK3S+ Electronics wiring diagram
MK3S+ Electronics wiring diagram
In the following step, we will connect the cables to the already existing connections on your Original Prusa MK3S+. Please, proceed very carefully.
Follow the diagram shown here in case you need to reconnect any of the extruder cables into the Einsy Rambo control board.
Since, MK2.5S printer isn’t officially supported in combination with the MMU3, this guide doesn’t cover connecting the electronics on it. Instead, it is described in the MK2.5S MMU2S guide.
MK3S+ Connecting the data and FS cables
MK3S+ Connecting the data and FS cables
MK3S+ Connecting the data and FS cables
MK3S+ Connecting the data and FS cables
Note the marked position. The MMU Signal cable connector should go here. (upper row of the pins, brown wire in the plug must be facing left)
Upper row of the pins, the brown wire in the plug must be facing left!
IR filament sensor cable is just below the MMU signal cable.
Bottom row of the pins, the white wire is facing left.
Verify the IR Filament sensor connector is installed correctly. Make sure it is plugged in correctly as there are several ways for it to go wrong!
Make sure the signal cable is properly connected to all pins!
MK3S+ Connecting the power cables
MK3S+ Connecting the power cables

Connect the Power cable fork connectors.

First, loosen the screws on the terminals so that there is enough space.

Stack the MMU power connectors on top of the the PSU cable connections in the first two clamps on the left side of the Einsy board.

The power cable connector "fork" has bent ends. Make sure they point up. See the picture for a reference.
Red (+ / positive) wire goes into the first slot.

Black (- / negative) wire goes into the second slot.
Tighten up the power cables firmly!
Confirm that the cables are connected in the correct order to avoid causing damage to the device.
MK3S+ Closing the electronics box
MK3S+ Closing the electronics box
MK3S+ Closing the electronics box
Close the door. Make sure no wire is being pinched while you close the door.
Tighten up the M3x40 screw from the other side to lock the door.
Software Download
Software Download
Software Download
Find the ORIGINAL PRUSA MMU3 on the list. In the Drivers & Apps section, download the latest package.
Leave this page open for the next steps!
Install the package on your computer and open PrusaSlicer.
PrusaSlicer app is part of the Drivers package. It includes the firmware upgrade tool. The Drivers package also includes some sample objects to be printed.
PrusaSlicer setup for MMU3
PrusaSlicer setup for MMU3
PrusaSlicer setup for MMU3
Open the PrusaSlicer Assistant / Wizard. (Configuration > Configuration Assistant > Prusa FFF)

Scroll down to MK3 Family and make sure that the corresponding printer + MMU3 option is selected, depending on which printer model you have.

The default nozzle is 0.4mm from factory.
Click Finish to close the Wizard.
In Printer: menu, select the MMU3 printer profile for future slicing.
Note, the MMU3 on MK3S+ is reverse-compatible with the older MMU2S Slicer profile and G-codes - but not with the MMU2 profiles!
Firmware files download
Firmware files download

You will need to update both the firmwares for the printer as well as the MMU unit. Use only a combination of the newest firmware versions for both devices together.

Please refer to the MMU3 Firmware Compatibility article to find out exactly which firmware version you need.
Go back to the help.prusa3d.com/downloads
Find the ORIGINAL PRUSA MMU3 on the list. Download the latest FIRMWARE file bundle.
Selecting a Printer firmware file
Selecting a Printer firmware file
Selecting a Printer firmware file
Open up the firmware bundle you have downloaded earlier. Open one of the folders depending on the printer model you have (select "MK3S" for MK3S+ model)
There are two firmware files in the folder. One for the printer, the other one for the MMU unit.
As a firmware file for the MK3S+, select the MK3S+  .hex file
On MK3S+ printer, MMU3 requires printer firmware 3.13 or newer!
If you are updating from a printer firmware 3.11 or older, the printer will require you to do a thermal model calibration first.
MK3S+ Firmware flashing (part 1)
MK3S+ Firmware flashing (part 1)
Connect the printer to the electricity and turn it on.

Now, let’s flash the printer’s firmware.

To flash the MK3S+, use the bundled USB Type B cable to connect the computer to the top of the black electronics box on the printer.

Then, continue to the next step.
MK3S+ Firmware flashing (part 2)
MK3S+ Firmware flashing (part 2)
MK3S+ Firmware flashing (part 2)
MK3S+ Firmware flashing (part 2)
Open PrusaSlicer and select Configuration ->Flash Printer Firmware from the top menu.
First, select the printer's firmware file on your computer.
(e.g. FW3.13.0-MK3S-EINSY10a_MULTILANG.hex)
Hit Rescan to make sure your printer appears in the Serial port: column
Hit the Flash button.
Wait until you see the Flashing succeeded message.
In case of any issues with flashing the firmware please visit our troubleshooting article.
MK3S+ Turning the MMU on and reset
MK3S+ Turning the MMU on and reset
MK3S+ Turning the MMU on and reset
After finishing the firmware update, make sure there are no filaments loaded neither in the extruder, or in the MMU unit.

Navigate to the LCD menu > Settings > MMU

and make sure it is set to MMU [On]

Hit the reset button on the printer's LCD box.
From now on, the reset button on the printer resets also the MMU unit. Wait for a while, the MMU unit will go through the self-test routine. (accompanied by flashing LED lights on the MMU unit) Wait until it boots up properly, before issuing any commands to the printer.
In case of necessity, the reset button is also useful to help you get out of some unrecoverable situations even for the MMU unit. But remember, it also aborts an ongoing print immediately.
MMU3 Firmware flashing (part 1)
MMU3 Firmware flashing (part 1)
MMU3 Firmware flashing (part 1)
MMU3 Firmware flashing (part 1)
The MMU3 firmware file needs to be flashed into the MMU unit itself. Find the microUSB connector on the right side of the MMU3 unit.
Connect the unit to your computer using the bundled microUSB cable.
On your computer, select the appropriate MMU firmware file compatible with your printer model.
MMU3 Firmware flashing (part 2)
MMU3 Firmware flashing (part 2)
MMU3 Firmware flashing (part 2)
MMU3 Firmware flashing (part 2)
Open PrusaSlicer and select Configuration ->Flash Printer Firmware from the top menu.
Hit Browse and select the MMU3 firmware image file on your computer.
(e.g. MMU3_3.0.0.hex)
Serial port should be auto-detected.
Hit the Flash button.
Wait until the Flashing Succeeded! message appears.
After the flashing finishes, disconnect the USB cable.
In case of any issues with flashing the firmware please visit our troubleshooting article.
IR filament sensor calibration (Part 1)
IR filament sensor calibration (Part 1)
IR filament sensor calibration (Part 1)
IR filament sensor calibration (Part 1)
In the following steps, we will calibrate the IR Filament sensor iside the Chimney on the extruder. Follow the instructions carefully, this part is very important!
Using a 2.5mm Allen key, make sure the lock screw for the chimney is not tightened up. Don't remove it entirely. It holds the chimney together.
Carefully tighten the calibration screw on the side so that the chimney moves all the way to the left.

When tightening the calibration screw, the chimney moves to the left, making it less sensitive to triggering.

When loosening the calibration screw, the chimney moves to the right, making it more sensitive to triggering.
Tighten the calibration screw until the chimney moves all the way to the left.
Insert a 1.5mm Allen key into the extruder. Don't push it all the way in yet.
Make sure you are using the thinnest of the bundled Allen keys; 1.5mm. Do not use the 2mm one!!
IR filament sensor calibration (Part 2)
IR filament sensor calibration (Part 2)
IR filament sensor calibration (Part 2)
IR filament sensor calibration (Part 2)

Go to Menu > Support > Sensor Info > Fil. sensor on your MK3S+

The Fil. sensor should indicate value 0 when the Allen key isn't pushed all the way in so the idler door isn't tilted outwards.

Now push the 1.5mm Allen key down until it reaches in between the Bondtech gears.
(don't be afraid to apply a fair amount of downwards force in order to get the key in between the gears)
The idler door on the right of the extruder should tilt outwards slightly simulating an inserted filament.

The Fil. sensor: line on the LCD now should indicate value 1 with the Allen key (or a filament) inserted. Keep releasing the calibration bolt until there is number 1 on the LCD.

Then, release it another half turn.

By rotating the calibration screw, we need to fine-tune the chimney position so that the number on the LCD reliably changes when inserting and removing the Allen key or filament from the Bontech gears.

IR filament sensor calibration (Part 3)
IR filament sensor calibration (Part 3)
IR filament sensor calibration (Part 3)
Calibrating the IR filament sensor is super-crucial in order for MMU3 unit to work properly!
Please, repeat this check several times.
Confirm the sensor works correctly: See the LCD again if the Fil. sensor number
displays 1 when Allen key (/filament) is inserted all the way
or 0 when it´s not inserted all the way in.
When the sensor works reliably and correctly, please lock the chimney in place by tightening the lock screw from the top.
After tightening the screw, verify the readings on the LCD are still correct when inserting and removing the Allen key.
More info on filament IR-sensor calibration is in Calibration procedure of the IR-sensor article, or in chapter 7.1 in the Handbook.
SuperFINDA sensor calibration info
SuperFINDA sensor calibration info
SuperFINDA sensor calibration info
SuperFINDA sensor calibration info
Good! You have calibrated your IR filament sensor. Now, we can move on to calibrating the SuperFINDA sensor inside the selector on the MMU unit.
In the next step, we will adjust the sensor's position and check if it detects the filament correctly.
It is EXTREMELY important that both the IR filament sensor and the SuperFINDA sensor work reliably and provide accurate readings. Otherwise, you will have trouble with the device.
There is an inspection window on the side of the selector where you can observe the SuperFINDA's position. It is a good starting point to line up the bottom of the SuperFINDA probe with the top of the inspection window when looking from the selector motor side.
If there is a filament in the selector, the steel ball is risen and should be detected by the SuperFINDA sensor. The distance between the ball and the sensor is what must be perfectly calibrated.
SuperFINDA calibration
SuperFINDA calibration
SuperFINDA calibration
SuperFINDA calibration
Take a piece of filament with a sharp tip and insert it into the selector through the brass threaded opening on the front.
Take a look at SuperFINDA from above and watch for the little red light inside the sensor to turn off when the filament raises the steel ball inside.

Red light = no filament detected = FINDA 0

No light = filament detected = FINDA 1

If the light is still on, lower the SuperFINDA slightly.

If the light doesn't go on, raise the SuperFINDA probe by releasing the screw by its side, moving the probe, and tightening the screw back up.

Watch the sensor readings on the LCD ( Menu > Support > Sensor info or Info > Sensor Info) Note, there is a slight lag in the sensor's readings on the LCD; proceed slowly.

Keep repeating the test by inserting and removing the filament. Watch the values on the LCD. Adjust the SuperFINDA height accordingly until you get reliable readings from the sensor each time you insert and remove the filament.
Error code details (Part 1)
Error code details (Part 1)

Later on, an MMU error screen will show up if something goes wrong during the operation. See the example image; the first line describes briefly, what's the error about.

prusa.io/04101 is a web address, where you can view a detailed article about the exact issue, and how to fix it.
FI:0 / SuperFINDA sensor reading. FI:0 / OFF = no filament detected. FI:1 / ON = it is detecting a filament.
(Note the FINDA status reading on the LCD has a slight delay.)
FS:0Filament Sensor reading. This is the sensor inside the chimney on the extruder / print head.

F1 is the expected filament position. It means, the selector is in the first position. 1>3 would mean, the selector is changing from the first to the third. F? = position not yet set.

Error code details (Part 2)
Error code details (Part 2)
Error code details (Part 2)
The bottom line are the solution buttons. Some errors have multiple solutions.
In the bottom right corner, selecting the two downward arrows will get you a more detailed error description and possible solution, if the error persists.
MMU unit being in an error state is also indicated by its LED lights flashing.
While in an ERROR state, the buttons on the MMU unit can be used to resolve the error too.
The middle button usually replicates the LCD solution buttons function.

Note, if the MMU unit is in IDLE state, the buttons have a different functions; For example; If there is no filament loaded, the side buttons can be used to move the selector right and left. But more on that later.

While in an error state, the printer might be beeping. You can change the Sound setting in the Tune or Settings menu.
MMU-to-Extruder PTFE tube parts preparation
MMU-to-Extruder PTFE tube parts preparation
MMU-to-Extruder PTFE tube parts preparation
For the following steps, please prepare:
360x2.5mm PTFE tube (1x)
The new PTFE tube has an internal diameter of 2.5mm. In case you are upgrading from the 2mm ID MMU2S tube, and you have trouble distinguishing between the old and the new one, try comparing the internal diameter of the two. See the second picture. The tube on the left is the new one.
A 2.5mm ID PTFE tube is required for the MMU3.
FESTO fittings (2x)
MMU-to-Extruder PTFE tube
MMU-to-Extruder PTFE tube
MMU-to-Extruder PTFE tube
MMU-to-Extruder PTFE tube
Attach the Festo fittings onto both sides of the new PTFE tube (4x2.5x360mm)
Push the PTFE tube in fully.
Quick tip: If you need to remove the PTFE tube from the fitting, press the blue collet in. While the collet is pressed, first press the PTFE tube in, then pull it out entirely.
Attach the PTFE tube onto the printer. One end goes onto the selector. The other goes onto the extruder. Tighten the fittings up using the Unikey.
Spoolholders setup
Spoolholders setup
Spoolholders setup

Congratulations! The hardest part is over.

The Buffer and spools setup in the picture is the one we will be trying to achieve. Arrange the spool holders and the buffer as seen in the picture.

Hook up the "printer holder" part on the buffer to the extrusion on the printer.
The PTFE tubes go from the spoolholders to the buffer. Then, from the buffer to the back of the MMU.
Note the spool holder positioning. It is important that filament has as straight path as possible and that nothing interferes. PTFE tubes should not be bent too much. Otherwise, the filaments will jam.
Note that due to the decreased filament friction in the MMU3 compared to the MMU2S, some of the 3rd-party MMU2S re-winding spool holders might no longer work with the MMU3.
Connecting Buffer PTFE tubes
Connecting Buffer PTFE tubes
Connecting Buffer PTFE tubes
Connecting Buffer PTFE tubes
Connect the PTFE tubes from the MMU unit to the BOTTOM row of collets on the buffer, ensuring you match the numbering on both the buffer and the MMU unit.
Attach each end of the PTFE tube from the Buffer to the PTFE holder on each Spool holder.
Make sure each spool holder is hooked up to the corresponding filament position number. (marked 1 to 5 on the MMU unit and the buffer.)
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