8. Preflight check & Calibration

Relevant for:

MMU2S

Last updated a year ago

Difficulty

Difficult

Steps

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Step 1 SuperPINDA calibration preparation (optional)

IMPORTANT: SuperPINDA adjustment is needed only in case you have disassembled the entire extruder and moved the sensor. If not (e.g. MK3S and MK3S+ owners), you can skip to step 5.

⬢

In the upcoming steps, we are going to re-calibrate the height of the SuperPINDA probe on the extruder.

⬢This calibration procedure is the same for printers equipped with the older P.I.N.D.A leveling sensor.

While moving the extruder, the X-axis motor works as an alternator. You will generate a small amount of electricity and the LCD might flicker. Move the extruder reasonably slowly and in the future always use the printer's controls.

Step 2 SuperPINDA adjustment (part 1)

Ensure the printer is turned off and not plugged in.

Don't place the steel sheet onto the heatbed during the entire SuperPINDA probe adjustment process. Wait for the Z calibration.

⬢Move the extruder manually all the way to the left.

⬢By rotating BOTH threaded rods at the same time on the Z-axis move the nozzle until you reach the heatbed. Try rotating both the rods equally!

Check again while looking from a different angle that the nozzle is slightly touching the heatbed. Make sure the nozzle is not scratching the surface and that the heatbed doesn't get bent during the whole procedure.

Step 3 SuperPINDA adjustment (part 2)

⬢Move the extruder carefully all the way to the right.

Be careful not to scratch the surface during the movement! If the nozzle starts digging into the heatbed, rise the right side of the X-axis by rotating the right Z motor slightly clockwise.

⬢If an adjustment is needed, you can lower the nozzle height by rotating the right Z motor counter-clockwise.

Step 4 SuperPINDA adjustment (part 3)

⬢Move the extruder to the center of the X-axis.

⬢Take a zip tie from the package and place it under the SuperPINDA sensor. Use the middle part of the zip tie, not the tip.

⬢Release the screw holding the SuperPINDA sensor and gently press the sensor down against the zip tie.

⬢Tighten the screw on the SuperPINDA holder again.

!!! DO NOT use glue to fix the SuperPINDA probe in the holder, you won't be able to release it again !!!

⬢The correct height of the SuperPINDA probe compared to the nozzle should be similar to the one in the last picture.

Step 5 Two types of the MMU firmware

IMPORTANT!!! Before you start downloading and flashing. There are two types of the firmware for the MMU2S. Make sure you can distinguish between them.

⬢EINSY RAMBo firmware: This firmware is flashed to the board inside the black electronics box near the heatbed. Use USB type B cable. (e.g. prusa3D_fw_MK3S_3_10_0_4481.hex or prusa3D_fw_MK25S_3_10_0_4481_RAMBo13a_en-cz.hex)

⬢MMU2S board firmware: This firmware is flashed to the board inside the MMU2S unit on the top of the frame. Use Micro-USB cable. (e.g. prusa3d_fw_MMU2board_1_0_6.hex)

Printer and MMU2S unit firmwares are both available to download as one package at prusa3d.com/drivers

PrusaSlicer won't let you accidentally flash incorrect firmware to each board.

Step 6 Download the necessary software

⬢

Visit help.prusa3d.com/downloads

⬢Find the ORIGINAL PRUSA MMU2S on the list. In the Drivers & Apps section, download the latest package.

Leave this page open for the next step!

⬢Install drivers on your Windows, macOS or Linux system.

PrusaSlicer is part of the drivers package. It includes the firmware upgrade tool. Drivers package also includes sample objects to be printed.

Step 7 Download the new firmware

⬢Go back to help.prusa3d.com/downloads to get the firmware for your printer and the MMU2S unit.

⬢Download the zip file with the latest MMU2S firmware to your computer and unzip it.

Note there are two types of the firmware for the MMU2S. One is for the MMU2S unit (top of the frame), the other for printer itself.

For the MK3S MMU2S and MK2.5S MMU2S use firmware combo 3.9.3 and 1.0.6 or latest. Do not use MMU2 firmware for MMU2S unit.

We will flash the firmware files in the next step. Make sure you have prepared both cables and the printer is turned ON.

Step 8 Updating both firmwares using PrusaSlicer

⬢Make sure the printer is turned on.

⬢Open PrusaSlicer and select Configuration ->Flash Printer Firmware from the top menu.

⬢First, select the printer's firmware file on your harddrive (.hex). Do not place the firmware on a network share.

⬢Connect the printer to your computer using the bundled USB Type B cable and select it from the menu. Hit Rescan if the printer is not in the list

⬢Hit the Flash button.

⬢Wait until the process is completed. You can click "Advanced: ..." to see the flashing process including a detailed log.

⬢When the flashing process is done, you will be informed.

⬢Now, repeat this step, but this time connect the MicroUSB cable and select the firmware for the MMU2S unit.

In case of any issues with flashing the firmware please visit our troubleshooting article.

Step 9 Adding MMU2S settings to the PrusaSlicer

Before you leave PrusaSlicer, please add the MMU2S printer profiles!!!

MMU2 and MMU2S G-codes aren't compatible!

⬢From the top menu select Configuration -> Configuration Wizard

⬢Look for the MMU2S options and select your printer

⬢Click Next, then Finish

⬢Expand the Printer menu and check if the MMU2S option is present. If not, please repeat the process again.

Step 10 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.

If you are using firmware 3.0.0 and up, the MMU has to be turned on in the menu before use.

⬢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.

Step 11 IR filament sensor calibration

⬢Release the PTFE tube from the extruder by unscrewing the fitting.

⬢Release the two screws holding the IR filament sensor chimney.

⬢Ensure the chimney can be moved left and right after releasing the two screws.

⬢Insert the 1.5mm Allen key into the extruder. Don't push it all the way in yet.

Step 12 IR filament sensor calibration 2

⬢

Go to Menu -> Support -> Sensor Info -> Fil. sensor

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 should indicate value 1 with the Allen key (or a filament) inserted.

⬢Move the chimney left or right until the number on the LCD reliably changes accordingly when inserting and removing the Allen key from the Bontech gears in the extruder!

Step 13 IR filament sensor calibration 3

Calibrating the IR filament sensor is super-crucial in order for MMU2S 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 two screws holding it with a 2.5mm Allen key.

⬢Install the PTFE back onto the extruder by screwing the fitting in.

More info on filament IR-sensor calibration is in Calibration procedure of the IR-sensor article, or in chapter 7.1 in the Handbook.

Step 14 SuperFINDA sensor calibration preparation

⬢

Congratulations, you have calibrated your IR filament sensor. Now we can move on to calibrating the SuperFINDA sensor inside the selector on the MMU2S.

⬢In the next step, we will check if the sensor detects the filament correctly and adjust its position if needed.

It is very important both IR filament sensor and SuperFINDA sensor work reliably and provide accurate readings.

⬢The newest MMU2S unit revision has inspection windows on the sides of the selector. It is a good starting point to line up the bottom of the SuperFINDA probe exactly with the top of the inspection window when looking from the selector motor side.

⬢Start by releasing the PTFE tube from the MMU2S selector by unscrewing the fitting.

Step 15 SuperFINDA calibration

⬢

Take a piece of filament with a sharp tip and insert it into the selector, into the hole you have removed the PTFE tube with fitting from in the previous step.

⬢

Take a look at the SuperFINDA probe from above and watch for the little red light inside the sensor go off when the filament raises the steel ball inside the selector.

⬢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 probe up again.

Repeat the test and adjust the SuperFINDA height accordingly until you have reliable readings from the probe each time you insert and remove filament.

If you can't see the light from above the SuperFINDA, you can see the readings in Menu -> Support -> Sensor info -> FINDA.

⬢After you are done calibrating your SuperFINDA, fully tighten the screw holding the sensor in place.

⬢

Attach the PTFE tube with fitting back onto the MMU2S unit.

Step 16 Preparing to load filaments for the test setup.

Congratulations! The hardest part is over. You have just successfully calibrated the sensors.

We can now move on to loading the filaments in and printing the test object!

⬢

The setup in the first picture is the one we are trying to achieve.

Note the spool holder positioning. It is important so no filament gets stuck and nothing interferes.

⬢Please prepare at least two different PLA filaments and make sure they both have a sharp tip at the end, as seen in the picture.

Step 17 Connecting the rear PTFE tubes

⬢Insert the PTFE from MMU2S unit to the buffer.

⬢Insert the M3x12 screw next to the PTFE and tighten it just so the PTFE doesn't come out. Don't over-tighten the screw. Excessive friction in the PTFE might cause issues during the printing later.

⬢Repeat the same for all the other PTFE tubes. You can organize the filament positions according to your preference.

Step 18 Loading a filament into the buffer

⬢Insert filament into the buffer until it reaches out on the other side. Grab it using needle-nose pliers.

⬢Guide the filament into the PTFE tube leading to the first, leftmost position on the MMU2S unit.

⬢Load at least two different PLA filaments into positions 1 and 2.

Step 19 Loading a filament into MMU2S

⬢Go to the Menu -> Load filament.

⬢Select filament position, and insert the filament end into the corresponding rear PTFE tube until the MMU units start pulling the filament in. The filament must be straight and have a sharp tip.

Filament positions are labeled 1,2,3,4,5 from the left to right.

⬢Repeat for the second filament.

8. Preflight check & Calibration

8. Preflight check & Calibration

Step 1 SuperPINDA calibration preparation (optional)

Step 2 SuperPINDA adjustment (part 1)

Step 3 SuperPINDA adjustment (part 2)

Step 4 SuperPINDA adjustment (part 3)

Step 5 Two types of the MMU firmware

Step 6 Download the necessary software

Step 7 Download the new firmware

Step 8 Updating both firmwares using PrusaSlicer

Step 9 Adding MMU2S settings to the PrusaSlicer

Step 10 Turning the MMU on and reset

Step 11 IR filament sensor calibration

Step 12 IR filament sensor calibration 2

Step 13 IR filament sensor calibration 3

Step 14 SuperFINDA sensor calibration preparation

Step 15 SuperFINDA calibration

Step 16 Preparing to load filaments for the test setup.

Step 17 Connecting the rear PTFE tubes

Step 18 Loading a filament into the buffer

Step 19 Loading a filament into MMU2S

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