Prusa research Prusa mmu3 User manual

Table of Contents

1. Introduction 7 .......................................................................................................................

Step 1 - MMU History and Printer Compatibility 8 ......................................................

Step 2 - Supported printers 9 ..........................................................................................

Step 3 - Disclaimer 9 ........................................................................................................

Step 4 - Tools required 10 ................................................................................................

Step 5 - View high resolution images 10 .......................................................................

Step 6 - Labels guide 11 ....................................................................................................

Step 7 - We are here for you! 11 .......................................................................................

Step 8 - Pro tip: inserting the nuts 12 .............................................................................

Step 9 - Printed parts 13 ...................................................................................................

Step 10 - Prepare your desk 14 ........................................................................................

Step 11 - Continue 14 .........................................................................................................

2. MMU2S Disassembly (UPG) 15 ....................................................................................

Step 1 - Introduction 16 .....................................................................................................

Step 2 - Tools necessary for this chapter 16 .................................................................

Step 3 - Disconnecting the PTFE tubes 17 ....................................................................

Step 4 - Disconnecting the MMU2S (part 1) 17 ............................................................

Step 5 - Disconnecting the MMU2S (part 2) 18 ...........................................................

Step 6 - Removing MMU2S from the printer 18 ..........................................................

Step 7 - MMU-to-Extruder PTFE tube disassembly 19 ...............................................

Step 8 - MMU2S Unit disassembly 20 ..........................................................................

Step 9 - Textile wrap removal 20 ....................................................................................

Step 10 - Idler motor removal 21 .....................................................................................

Step 11 - 5x16sh shafts removal 21 ..................................................................................

Step 12 - Bearings removal 22 .........................................................................................

Step 13 - Selector motor removal 22 ..............................................................................

Step 14 - Selector removal 23 ..........................................................................................

Step 15 - Pulley motor removal 23 ..................................................................................

Step 16 - Selector disassembly 24 ..................................................................................

Step 17 - Control board disassembly 24 ........................................................................

Step 18 - Summary 25 ......................................................................................................

3. MMU2S Buffer Disassembly (UPG) 26 .....................................................................

Step 1 - Preparation 27 ......................................................................................................

Step 2 - Disconnecting the PTFE tubes 27 ...................................................................

Step 3 - Buffer disassembly 28 .......................................................................................

Step 4 - Summary 28 ........................................................................................................

4. Idler Body Assembly 29 ...................................................................................................

Step 1 - Tools necessary for this chapter 30 .................................................................

Step 2 - Idler versions 30 ..................................................................................................

Step 3 - Idler parts preparation 31 ..................................................................................

Step 4 - Idler bearings assembly (part 1) 31 ..................................................................

Step 5 - Idler bearings assembly (part 2) 32 .................................................................

Step 6 - Idler center bearing assembly 32 ....................................................................

Step 7 - Coupler parts preparation 33 ...........................................................................

Step 8 - Coupler preparation 33 .....................................................................................

Step 9 - Coupler assembly 34 .........................................................................................

Step 10 - Final check 34 ...................................................................................................

Step 11 - Idler Body parts preparation 35 ......................................................................

Step 12 - Silicone stopper instalation 35 .......................................................................

Step 13 - Idler installation 36 ...........................................................................................

Step 14 - Idler center shaft assembly 36 .......................................................................

Step 15 - Idler body M3nS nut 37 ...................................................................................

Step 16 - Idler motor assembly (part 1) 37 .....................................................................

Step 17 - Idler motor assembly (part 2) 38 ....................................................................

Step 18 - Idler motor assembly (part 3) 38 ....................................................................

5. Selector Assembly 39 ......................................................................................................

Step 1 - Tools necessary for this chapter 40 .................................................................

Step 2 - Selector assembly: Parts preparation 40 .......................................................

Step 3 - Selector assembly: Magnetic ball 41 ...............................................................

Step 4 - Selector assembly: Trapeze nut parts preparation 41 .................................

Step 5 - Selector assembly: Trapeze nut installation 42 ............................................

Step 6 - Selector assembly: Rods and Cover parts preparation 42 ..........................

Step 7 - Selector assembly: Bronze bushing tubes 43 ...............................................

Step 8 - Selector assembly: Rods and Cover 43 ..........................................................

Step 9 - Selector assembly: Finda parts preparation 44 ............................................

Step 10 - Selector assembly: SuperFINDA probe 44 ..................................................

Step 11 - Selector assembly: Cutter parts preparation 45 ..........................................

Step 12 - Selector assembly: Cutter assembly 45 .......................................................

6. Pulley Body Assembly 46 ...............................................................................................

Step 1 - Tools necessary for this chapter 47 .................................................................

Step 2 - Pulley-body parts preparation 47 .....................................................................

Step 3 - Pulley body: Inserting bearings 48 ..................................................................

Step 4 - Pulley-body parts preparation 48 ....................................................................

Step 5 - Front-PTFE-holder assembly 49 ......................................................................

Step 6 - Collet holder parts preparation 49 ..................................................................

Step 7 - Collets installation 50 ........................................................................................

Step 8 - Collet holder installation 50 .............................................................................

Step 9 - Pulley motor parts preparation 51 ...................................................................

Step 10 - Pulley assembly 51 ............................................................................................

Step 11 - Pulley motor assembly (part 1) 52 ...................................................................

Step 12 - Pulley motor assembly (part 2) 52 .................................................................

Step 13 - Pulley alignment 53 ..........................................................................................

Step 14 - Selector: parts preparation 53 ........................................................................

Step 15 - Selector installation 54 ....................................................................................

Step 16 - Selector movement check / motor prep 54 .................................................

Step 17 - Selector motor installation 55 .........................................................................

Step 18 - Trapezoid nut positioning 55 ..........................................................................

Step 19 - Idler body installation parts preparation 56 .................................................

Step 20 - Idler body installation (part 1) 56 ...................................................................

Step 21 - Idler body installation (part 2) 57 ...................................................................

Step 22 - Idler body installation (part 3) 57 ..................................................................

Step 23 - Control board parts preparation 58 ..............................................................

Step 24 - Control board assembly 58 ............................................................................

Step 25 - PD-board parts preparation 59 ......................................................................

Step 26 - PD-board installation 59 .................................................................................

Step 27 - Textile sleeve parts preparation 60 ...............................................................

Step 28 - Connecting the cables 60 ...............................................................................

Step 29 - Electronics assembly 61 ..................................................................................

Step 30 - Cable management (part 1) 61 .......................................................................

Step 31 - Cable management (part 2) 62 ......................................................................

Step 32 - Frame holders parts preparation 62 .............................................................

Step 33 - Frame holders assembly 63 ...........................................................................

Step 34 - Label plate installation 63 ..............................................................................

Step 35 - Rear PTFE parts preparation 64 ....................................................................

Step 36 - Rear PTFE installation 64 ...............................................................................

Step 37 - Setting the Idler tension 65 ............................................................................

Step 38 - Stickers parts preparation 65 ........................................................................

Step 39 - Applying the stickers 66 .................................................................................

7. Cassette Buffer Assembly 67 ........................................................................................

Step 1 - Tools necessary for this chapter 68 .................................................................

Step 2 - Parts preparation 68 ..........................................................................................

Step 3 - Peeling the plates 69 .........................................................................................

Step 4 - Assembly (part 1) 69 ..........................................................................................

Step 5 - Assembly (part 2) 70 ..........................................................................................

Step 6 - Assembly (part 3) 70 ..........................................................................................

Step 7 - Assembly (part 4) 71 ...........................................................................................

Step 8 - Assembly (part 5) 71 ...........................................................................................

Step 9 - Parts preparation: Plate-holders 72 .................................................................

Step 10 - Assembly (part 6) 72 ........................................................................................

Step 11 - Buffer segment parts preparation 73 .............................................................

Step 12 - Segment assembly (part 1) 73 ........................................................................

Step 13 - Segment assembly (part 2) 74 ........................................................................

Step 14 - Segment assembly (part 3) 74 ........................................................................

Step 15 - Collets: parts preparation 75 ...........................................................................

Step 16 - Collet instalation 75 ..........................................................................................

Step 17 - Cartridge installation 76 ..................................................................................

Step 18 - PTFE tubes parts preparation 76 ...................................................................

Step 19 - PTFE tubes installation 77 ...............................................................................

8. Spool holder Assembly 78 ..............................................................................................

Step 1 - Two Spoolholder types 79 .................................................................................

Step 2 - Vacuum formed holder parts preparation 79 ................................................

Step 3 - Foam pads installation 80 .................................................................................

Step 4 - Rods, Bearings parts preparation 80 ..............................................................

Step 5 - Rods and bearings assembly 81 .......................................................................

Step 6 - Finishing up the Spoolholders (vac. form.) 81 ...............................................

Step 7 - Injection molded spoolholder: parts preparation 82 ....................................

Step 8 - Injection molded holder parts preparation 82 ...............................................

Step 9 - Base assembly (part 1) 82 .................................................................................

Step 10 - Base assembly (part 2) 83 ...............................................................................

Step 11 - Foam pads installation (part 1) 83 ..................................................................

Step 12 - Foam pads installation (part 2) 84 .................................................................

Step 13 - PTFE holder assembly 84 ................................................................................

Step 14 - Finishing up the Spoolholders (inj. mol.) 85 ................................................

Step 15 - Joining the Spoolholder Guides 85 ................................................................

Step 16 - Continue 86 .......................................................................................................

9B. MK3S+ Extruder mod (KIT) 87 ..................................................................................

Step 1 - Tools necessary for this chapter 88 .................................................................

Step 2 - Printer preparation 88 ........................................................................................

Step 3 - Releasing the cable bundle 89 .........................................................................

Step 4 - Unplugging the IR filament sensor cable 89 .................................................

Step 5 - X-carriage-back disassembly 90 .....................................................................

Step 6 - FS-cover and hotend fan disassembly 90 .....................................................

Step 7 - Extruder-body disassembly 91 .........................................................................

Step 8 - IR Filament sensor cable 91 ..............................................................................

Step 9 - Hotend PTFE tube INFO 92 ..............................................................................

Step 10 - Splitting the extruder 92 .................................................................................

Step 11 - Partial extruder disassembly 93 ......................................................................

Step 12 - PTFE tube parts preparation 93 .....................................................................

Step 13 - Old PTFE tube removal 94 ..............................................................................

Step 14 - New PTFE tube installation 94 .......................................................................

Step 15 - Extruder reassembly (Part 1) 95 .....................................................................

Step 16 - Extruder reassembly (Part 2) 95 ....................................................................

Step 17 - Extruder reassembly (Part 3) 96 .....................................................................

Step 18 - Adapter-printer parts preparation 96 ............................................................

Step 19 - Adapter-printer assembly 97 ..........................................................................

Step 20 - New chimney: parts preparation 97 .............................................................

Step 21 - New chimney assembly (Part 1) 98 ................................................................

Step 22 - New chimney assembly (Part 2) 98 ..............................................................

Step 23 - New chimney assembly (part 3) 99 ..............................................................

Step 24 - IR Filament sensor: parts preparation 99 ....................................................

Step 25 - IR Filament sensor assembly 100 ..................................................................

Step 26 - Extruder-idler disassembly 100 .....................................................................

Step 27 - Extruder-idler-mmu parts preparation 101 ..................................................

Step 28 - Bearing assembly & Greasing 101 .................................................................

Step 29 - Extruder-idler-mmu assembly (Part 1) 102 ..................................................

Step 30 - Extruder-idler-mmu assembly (Part 2) 102 .................................................

Step 31 - Extruder fasteners parts preparation 103 .....................................................

Step 32 - Extruder reassembly 103 .................................................................................

Step 33 - Extruder-idler-mmu installation 104 .............................................................

Step 34 - X-carriage-back reassembly 104 ...................................................................

Step 35 - Zip-Ties! 105 ......................................................................................................

Step 36 - Tightening the textile sleeve 105 ...................................................................

Step 37 - Attaching the hotend cables 106 ...................................................................

Step 38 - Attaching the cable bundle 106 .....................................................................

9C. MK3S+ Extruder (UPG) 107 .........................................................................................

Step 1 - Tools necessary for this chapter 108 ...............................................................

Step 2 - Introduction 108 ..................................................................................................

Step 3 - Old chimney disassembly (part 1) 109 ............................................................

Step 4 - Old chimney disassembly (part 2) 109 ...........................................................

Step 5 - Old chimney disassembly (part 3) 110 ............................................................

Step 6 - Hotend PTFE tube INFO 111 ..............................................................................

Step 7 - Fan removal 111 ....................................................................................................

Step 8 - Splitting the extruder 112 ..................................................................................

Step 9 - Partial extruder disassembly 112 ......................................................................

Step 10 - PTFE tube parts preparation 113 ....................................................................

Step 11 - Old PTFE tube removal 113 ..............................................................................

Step 12 - New PTFE tube installation 114 ......................................................................

Step 13 - Extruder reassembly (Part 1) 114 ....................................................................

Step 14 - Extruder reassembly (Part 2) 115 ....................................................................

Step 15 - Extruder reassembly (Part 3) 115 ....................................................................

Step 16 - Extruder fan reassembly 116 ...........................................................................

Step 17 - New chimney: parts preparation 116 ..............................................................

Step 18 - New chimney assembly (part1) 117 ................................................................

Step 19 - New chimney assembly (part 2) 117 ...............................................................

Step 20 - New chimney assembly (part 3) 118 .............................................................

Step 21 - IR Filament sensor: parts preparation 118 ....................................................

Step 22 - IR Filament sensor assembly 119 ...................................................................

Step 23 - Extruder-idler-mmu2s parts preparation. 120 ............................................

Step 24 - Bondtech lubrication 120 ................................................................................

Step 25 - Extruder-idler-mmu2s installation. 121 ........................................................

Step 26 - Opening the electronics box 121 ....................................................................

10B. MK3S+ Setup and Calibration 122 .........................................................................

Step 1 - Tools necessary for this chapter 123 ................................................................

Step 2 - Attaching the MMU unit (part 1) 123 ...............................................................

Step 3 - Attaching the MMU unit (part 2) 124 ..............................................................

Step 4 - Guiding the MMU cable 124 .............................................................................

Step 5 - Trimming the electronics box door 125 ..........................................................

Step 6 - Trimmed electronics door installation 125 .....................................................

Step 7 - Electronics wiring diagram MK3S+ 126 .........................................................

Step 8 - Connecting the data and FS cables 126 .........................................................

Step 9 - Connecting the power cables 127 ....................................................................

Step 10 - Closing the electronics box 127 ......................................................................

Step 11 - Software Download 128 ....................................................................................

Step 12 - PrusaSlicer setup for MMU3 129 ...................................................................

Step 13 - MMU3 Firmware image download 129 .........................................................

Step 14 - MMU3 Firmware flashing (part 1) 130 ..........................................................

Step 15 - MMU3 Firmware flashing (part 2) 130 ..........................................................

Step 16 - MK3S+ Firmware image download 131 ........................................................

Step 17 - MK3S+ Firmware flashing (part 1) 131 ..........................................................

Step 18 - MK3S+ Firmware flashing (part 2) 132 .........................................................

Step 19 - Turning the MMU on and reset 133 ...............................................................

Step 20 - IR filament sensor calibration (Part 1) 134 ...................................................

Step 21 - IR filament sensor calibration (Part 2) 135 ...................................................

Step 22 - IR filament sensor calibration (Part 3) 136 ...................................................

Step 23 - SuperFINDA sensor calibration info 137 ......................................................

Step 24 - SuperFINDA calibration 138 ..........................................................................

Step 25 - Error code details (Part 1) 139 ........................................................................

Step 26 - Error code details (Part 2) 140 .......................................................................

Step 27 - MMU-to-Extruder PTFE tube parts preparation 141 ..................................

Step 28 - MMU-to-Extruder PTFE tube 141 ..................................................................

Step 29 - Spoolholders setup 142 ...................................................................................

Step 30 - Connecting Buffer PTFE tubes 142 ..............................................................

11. First Flight 143 ....................................................................................................................

Step 1 - Filament preparation 144 ...................................................................................

Step 2 - Suggested filament layout 144 .........................................................................

Step 3 - Loading a filament through the buffer 145 ....................................................

Step 4 - Preloading filaments to MMU 145 ...................................................................

Step 5 - Closing the buffer 146 ........................................................................................

Step 6 - Pro tip: Loading using the buttons. 147 ..........................................................

Step 7 - Loading test (part 1) 148 .....................................................................................

Step 8 - Loading test (part 2) 148 ....................................................................................

Step 9 - Z axis and first layer calibration (optional) 149 .............................................

Step 10 - Running a test print 149 ...................................................................................

Step 11 - Print & Follow the Handbook. 150 ...................................................................

Step 12 - Printable 3D models 150 ..................................................................................

Step 13 - G-code preparation / Custom model preparation 151 ...............................

Step 14 - Making your own Multi-material models 151 ...............................................

Step 15 - MMU Single material operation 152 ..............................................................

Step 16 - Reward yourself 152 .........................................................................................

Original Prusa MMU3 Assembly 7

1. Introduction

8Original Prusa MMU3 Assembly

STEP 1 MMU History and Printer Compatibility

Welcome to the MMU3 assembly guide! There were several generations of the

Original Prusa Multi-Material printing solution. Verify you are looking at the correct

guide for your MMU unit and your printer.

MMU1 for MK2 and MK2S printers (introduced in 2016-2018)

It used four separate extruders feeding one nozzle.

MMU2 for MK2.5 and MK3 (2018-2019) Five filaments feeding one direct-drive

extruder.

MMU2S for MK2.5S, MK3S, MK3S+ (2019-2023)

Introduced a chimney on the extruder with the IR-filament sensor.

And finally, the current model:

MMU3 for MK3S+, MK4 (2023-now)

MMU3 is the one we will be dealing with in this guide.

1. Introduction

Original Prusa MMU3 Assembly 9

STEP 2 Supported printers

Original Prusa Multi-Material MMU3 is currently officially supported only in

combination with these printer models:

Original Prusa i3 MK3S+

Original Prusa MK4

(support for MK4 will be announced later on)

If you have an older machine like the MK3 or MK3S, it is recommended to upgrade

it to MK3S+ first.

For more info on Printer compatibility, visit the MMU3 Firmware Compatibility

article.

STEP 3 Disclaimer

Make sure your printer is fully assembled and works perfectly before you proceed

to attach the MMU3 onto it. Make a few single material prints. If it has any issues,

fix the issues first. Diagnosing printer issues can be harder with the MMU attached.

As you embark upon the assembly process, we cannot stress the importance of

carefully following each and every step.

1. Introduction

10 Original Prusa MMU3 Assembly

STEP 4 Tools required

The required tools are available as an optional bundle:

Needle-nose pliers (1x)

Universal wrench (1x)

Philips PH2 screwdriver (1x)

Allen key 1.5mm (2x) the short and long one

Allen key 2mm (1x)

Allen key 2.5mm (1x) the short and ball-end long one.

For some chapters, as an extra, we advise considering:

- a measurement tool; a caliper or digital caliper would work the best. Or - you can

print one.

- Flush cutters might come in handy during the assembly too.

STEP 5 View high resolution images

When you browse the guide on

help.prusa3d.com, you can view the

original images in high resolution

for clarity.

Just hover your cursor over the

image and click the Magnifier icon

("View original") in the top left

corner.

1. Introduction

Original Prusa MMU3 Assembly 11

STEP 6 Labels guide

All the boxes and bags containing the parts for the build are labeled.

Most of the part drawings on the labels are scaled 1:1 and can be used to identify a

part.

You can download and 2D print a Prusa Cheatsheet with the 1:1 scaled fastener

drawings. help.prusa3d.com/cheatsheet. Print it at 100 %, don't rescale it,

otherwise, it won't work.

STEP 7 We are here for you!

Lost in the instructions, missing screw or cracked printed part? Let us know!

You can contact us using following channels:

Using our 24/7 live chat

Or by writing an email to [email protected]

Or, you can use the comments under each step.

1. Introduction

12 Original Prusa MMU3 Assembly

STEP 8 Pro tip: inserting the nuts

Some parts require you to use an Allen key at an angle to tighten a screw.

Even though the key is angled, make sure the screw is perfectly perpendicular to

the thread while tightening it. If it is hard to turn, release the screw fully, re-align it,

and start tightening it from the beginning to avoid cross-threading it!

For deep openings, use a long screw such as the M3x30 as a handle.

If a hex nut won't fit in: use a screw with a thread along its entire length (typically:

M3x10, M3x18) and screw it from the opposite side of the opening to drive the nut

in.

1. Introduction

Original Prusa MMU3 Assembly 13

STEP 9 Printed parts

If you prefer to print the plastic parts yourself, use the pre-sliced G-codes and print

all the required parts before proceeding with the assembly.

The printed parts must be printed perfectly in order for the MMU3 to work

correctly: no warping or lifted corners, stringing or other irregularities.

If you can’t guarantee the parts being flawless, get the MMU3 kit with the

factory-printed plastic parts instead of printing it yourself.

In case some parts get broken during the assembly, you can reprint them. Please

check all plastic parts before starting your build to make sure there are no issues.

The MMU3 printable parts will be available at prusa3d.com/prusa-i3-printable-

parts/

The recommended material is PETG.

If you opt to slice the parts yourself, use PrusaSlicer with 0.2 mm layer height,

GRID infill at 20%. No supports are required.

1. Introduction

14 Original Prusa MMU3 Assembly

STEP 10 Prepare your desk

Tidy up your desk! Tidying up decreases the probability of losing small parts.

Clear your workspace. Make sure you have enough room. A nice clear flat

workbench will get you the results you are aiming for.

Let there be light! Make sure you are in a well-lit environment. Another lamp or

even an extra flashlight will probably come in handy.

Prepare something to contain the plastic bags and the removed packing materials

so you can recycle them afterwards. Make sure there are no important parts being

discarded.

OK, we are ready. Let's start!

STEP 11 Continue

If you’re building a brand new MMU3 Kit from scratch, continue to the chapter:

4. Idler Body Assembly

For the MMU2S to MMU3 Upgrade, continue to the chapter:

2. MMU2S Disassembly (UPG)

Original Prusa MMU3 Assembly 15

2. MMU2S Disassembly (UPG)

16 Original Prusa MMU3 Assembly

STEP 1 Introduction

In this chapter, we will partly disassemble the MMU2S unit and harvest a few key

parts to be used for the MMU3 build.

Ensure your MMU printer is powered off and disconnected. Unload all filaments

from both the printer and the MMU unit.

If there is a filament loaded in the extruder, use the Unload filament function in

the menu.

In the upcoming steps, we'll start by detaching the MMU unit from the printer and

disconnecting the buffer from it.

Pay close attention to the description. When instructed, put aside the components

from the MMU2S. Specific parts will be used again in a later step.

Maintain a well-organized workspace to avoid mixing older parts with the new

ones. Although some new components might resemble the old ones, they are

actually distinct. Note that certain components shouldn't be reused for MMU3,

while others are necessary for the upgrade.

STEP 2 Tools necessary for this chapter

Please prepare tools for this

chapter:

Needle-nose pliers

Unikey to loosen the Festo

fittings

2.5mm Allen key(s) for M3

screws

Phillips screwdriver for power

cable terminals

You can use your own tools if you

find them more suitable.

2. MMU2S Disassembly (UPG)

Original Prusa MMU3 Assembly 17

STEP 3 Disconnecting the PTFE tubes

Unscrew the Festo fittings QSM-M5 from both the printer and the MMU unit. If the

fittings are tight, you can use the Unikey or an 8mm wrench.

Keep the PTFE tube with the fittings aside for disassembly later.

We will have to disconnect the buffer from the MMU unit.

Loosen all the screws on the buffer securing the PTFE tubes connected to the

MMU unit. Remove all five tubes by pulling them out.

Keep the buffer for a later disassembly in the next chapter.

On the back of the MMU unit, slightly loosen the four screws holding the rear-PTFE

holder.

Remove all five PTFE tubes and dispose of them immediately. These tubes will

not be used again for MMU3.

MMU3 is designed to work with differently-sized PTFE tubes. Reusing MMU2S

tubes during the assembly of MMU3 will result in incorrect operation.

STEP 4 Disconnecting the MMU2S (part 1)

Loosen the M3x40 screw on the printer's electronics box.

Open up the electronics box.

From the MMU, you'll see a data cable along with two power cables, all connected

to the Einsy control board of the printer.

Never move, connect, or disconnect cables while the printer is powered on. Doing

so can cause damage to the electronics.

Begin by disconnecting the MMU data cable.

Be careful not to disconnect the Filament sensor cable located just below the

MMU data cable.

2. MMU2S Disassembly (UPG)

18 Original Prusa MMU3 Assembly

STEP 5 Disconnecting the MMU2S (part 2)

With a Philips screwdriver, gently loosen the two power terminals located on the

bottom left side of the Einsy board.

The MMU power cable fork connectors are stacked over the main power supply

connectors for the Einsy. Remove only the MMU's fork connectors individually,

leaving the main supply connectors in place.

Using the Philips screwdriver, thoroughly secure the power terminals with the

MMU disconnected. Confirm that all connections match the picture.

Take out the MMU cable bundle from the electronics box. Close the box and secure

it using the M3x40 screw for now.

STEP 6 Removing MMU2S from the printer

The MMU2S unit has been successfully disconnected.

Raise the rear of the unit to detach the holders from the printer's frame. Then,

remove the MMU from the printer.

You can set the printer aside for now.

We can move onto disassembling the MMU2S unit itself.

For the following step, please prepare the MMU-to-Extruder PTFE tube with the

Festo fittings QSM-M5 attached.

2. MMU2S Disassembly (UPG)

Original Prusa MMU3 Assembly 19

STEP 7 MMU-to-Extruder PTFE tube disassembly

Take the MMU-to-Extruder PTFE tube with the Festo fittings QSM-M5.

Remove both Festo fittings on the old PTFE tube.

Hold the Festo fitting by the metal part and press the blue collet in. While the

collet is pressed, first press the PTFE tube in, then pull it out entirely.

Save the Festo fittings for later use. Discard the PTFE tube so you don't confuse it

with a new one later on!

MMU3 is designed to work with differently-sized PTFE tubes. Reusing MMU2S

tubes during the assembly of MMU3 will result in incorrect operation.

2. MMU2S Disassembly (UPG)

20 Original Prusa MMU3 Assembly

STEP 8 MMU2S Unit disassembly

Remove the two M3x18 screws holding the electronics on top of the unit.

Remove the two M3x30 idler tension screws with the springs.

Remove the electronics board assembly from the unit.

Disconnect all cables from the electronics board. Remember that each connector

has a safety latch that needs to be pushed in order to remove a plug. Set aside the

board assembly.

Gently cut the zip ties that are securing the cables together.

Be extremely careful not to damage the cables!

STEP 9 Textile wrap removal

Separate the power and data cable bundle from the rest of the cables.

Remove the textile wrap off the cables and save the textile wrap for later use.

The MMU2S power and data cables won’t be used in MMU3.

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