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10C. MK3.5 Setup and Calibration

10C. MK3.5 Setup and Calibration

10C. MK3.5 Setup and Calibration
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Last updated 23 days ago
10C. MK3.5 Setup and Calibration
 Difficulty
Difficult
 Steps
26
 Available languages
CSPLDEITFR
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.
Guiding the cable
Guiding the 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.
MK3.5 Cable installation
MK3.5 Cable installation
MK3.5 Cable installation
MK3.5 Cable installation
Take the Ext-cable-holder-a plastic component. There is a small part that needs to be breaked off in order to make space for the MMU cable. Remove the part using needle-nose pliers.
Similarly, remove the break-off part on the Ext-cable-holder-b.
Loosen the two M3x10 screws on top of the cable cover.
Guide the MMU/Printer cable through the corresponding opening into the xBuddy box.
MK3.5 Cable management
MK3.5 Cable management
MK3.5 Cable management
MK3.5 Cable management
Plug the MMU/Printer cable into the corresponding connector on top of the xBuddy board.
Attach the cable-holder-b back onto the xBuddy box using two M3x10 screws.
Insert two new zip-ties into the marked opening on the inside of the xBuddy box. Make sure the zip-ties wrap around the cable bundle.
Attach the cable-holder-a part using two M3x18 screws. Make sure no cable is getting pinched.
To verify the remaining cable connections are connected properly, refer to the MK3.5 assembly guide
MK3.5 Closing the electronics box
MK3.5 Closing the electronics box
MK3.5 Closing the electronics box
Ensure all connectors in the cable bundle remain fully inserted.
Wrap the zip-ties around the cable bundle and gently tighten. Cut off the remaining zip-tie.
Secure the zip-ties snugly but not too tight to avoid the risk of accidentally disconnecting or damaging the cables.
Align the xBuddy box cover with the xBuddy box and secure it with four M3x6 screws.
Software Download
Software Download
Software Download
Visit the MMU3 page on Help.Prusa3D.com
Download the latest Drivers & Apps package.
Leave this page open for the upcoming steps!
Install the downloaded package on your computer and open the PrusaSlicer app.
PrusaSlicer 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 MK3.5 Family and make sure that the corresponding printer + MMU3 option is selected.
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 MK3.5 is reverse-compatible with the older MK3S+ MMU3 or 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.
Head back to Help.Prusa3D.com
Download the lastest Firmware package for your printer model.
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 dedicated to the MK3.5 printer (marked by MK35)
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 MK3.5, select the MK35 .bbf file
MK3.5 Firmware flashing (part 1)
MK3.5 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 MK3.5 printer, insert a USB drive with the firmware file into the printer. Then, restart the printer using the reset button.
On the Firmware update screen, choose "FLASH" and wait for the process to complete.
MK3.5 Turning the MMU on
MK3.5 Turning the MMU on
MK3.5 Turning the MMU on
MK3.5 Turning the MMU on
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 the MMU is turned on.
This option not only turns on the MMU functionality in the firmware, but also turns on the power for the MMU unit, which is necessary to do a FW update.
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.
Since you've converted the extruder to the MMU version, when prompted to reconfigure the filament sensor's behavior, which will appear immediately, choose 'Continue'.
Extruder type can be changed in Settings > Hardware > Extruder
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 Info > Sensor Info on MK3.5

The Fil. sensor should indicate NINS (not inserted) 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 Filament sensor line on the LCD now should indicate value INS with the Allen key (or a filament) INSerted. Keep releasing the calibration bolt until there is INS 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 Filament sensor number
displays INS when Allen key (/filament) is inserted all the way
or NINS 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.
SuperFINDA sensor calibration info
SuperFINDA sensor calibration info
SuperFINDA sensor calibration info
SuperFINDA sensor calibration info
If you built the MMU3, the SuperFINDA sensor inside the selector must be calibrated.
For factory-assembled MMU3 units, the SuperFINDA is pre-calibrated, so you can skip the calibration steps.
In the next step, we'll calibrate the sensor's position.
It is CRITICAL that both the filament sensor in the extruder and the SuperFINDA sensor function accurately. Otherwise, you will have trouble with the device.
Use the inspection window on the selector to align the bottom of the sensor with the top of the window, as a starting point.
When filament is in the selector, the steel ball rises and should be detected by the SuperFINDA sensor. Ensure the distance between the ball and the sensor is 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 NINS / 0 / OFF

No light = filament detected = FINDA INS / 1 / ON
If the light is still on, lower the SuperFINDA slightly.

If the light doesn't ever 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 (Info > Sensor Info -> FINDA ) Note, there is a slight lag in the sensor's readings on the LCD; proceed slowly.
Repeat the test, adjusting SuperFINDA height until consistent readings occur when inserting and removing 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.
The status of the filament sensor is always displayed in the Footer section of the error screen to assist in diagnosis.
Adjacent to it, you will find the status of the Finda sensor.
(Note the FINDA status reading on the LCD has a slight delay.)
Error code details (Part 2)
Error code details (Part 2)
The bottom line are the solution buttons. Some errors have multiple solutions.
You can also visit a detailed error description page via the QR code.
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.
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.
M5-4 fittings (2x)
The fittings may have either a blue or a black collet. Functionally, they are the same.
MMU-to-Extruder PTFE tube
MMU-to-Extruder PTFE tube
MMU-to-Extruder PTFE tube
MMU-to-Extruder PTFE tube
Attach the M5-4 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 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
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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