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  1. Before you start, make sure that:
    • Before you start, make sure that:

    • the filament is unloaded from the hotend

    • the printer is properly cooled down

    • the printer is unplugged

    • you removed the steel sheet

    • This chapter is dedicated only to the MK3S/MK2.5S owners. If you have older MK3/MK2.5, please follow: 2A. MK3/MK2.5 - extruder disassembly

  2. MK3S and MK3S MMU2S extruders are very similar, we need just to change few parts, but we have to release the cable bundle. We need to gently pull the IR-sensor cable back to the extruder as the sensor will be in a different position. Make sure the entire path of the cable is free. However there is no need for complete disassembly. Using an Allen key release the M3x40 screw and open the door.
    • MK3S and MK3S MMU2S extruders are very similar, we need just to change few parts, but we have to release the cable bundle.

    • We need to gently pull the IR-sensor cable back to the extruder as the sensor will be in a different position. Make sure the entire path of the cable is free. However there is no need for complete disassembly.

    • Using an Allen key release the M3x40 screw and open the door.

    • Release two M3x10 screws and remove the extruder-cable-clip. On older printers cut the zip tie.

    • In case there are zip ties inside the Einsy-case, carefully remove them.

    • Remove the zip ties on the cable holder.

    • Keep the textile sleeve on the cables, but make sure the cable can slip inside. It might be twisted around other cables, in such case, you have to remove the sleeve.

  3. Carefully unplug the filament sensor cable and make sure it can be pulled from the Einsy case in the textile sleeve.
    • Carefully unplug the filament sensor cable and make sure it can be pulled from the Einsy case in the textile sleeve.

  4. Release all four M3x10 screws on the X-carriage-back, but keep them in the printed part. Move the X-carriage-back back about 10 mm (0.4 inch) to ensure the cables can move back and forth.
    • Release all four M3x10 screws on the X-carriage-back, but keep them in the printed part.

    • Move the X-carriage-back back about 10 mm (0.4 inch) to ensure the cables can move back and forth.

    • While releasing other screws in the next steps, make sure to check each screw is still holding all the parts. If you release the screws above certain level, the entire body will fall apart.

  5. Release the M3x10 screw and remove it. Remove the FS-cover it will be replaced with a new one. Release the screw holding the idler, you can leave it in the extruder.
    • Release the M3x10 screw and remove it.

    • Remove the FS-cover it will be replaced with a new one.

    • Release the screw holding the idler, you can leave it in the extruder.

    • Release the M2x8 screw and carefully unplug the IR-sensor. Keep it safe, you will need the sensor for the reassembly.

    • Release both M3x40 screws, just few turns to create about 0.5cm (0.2inch) gap in the extruder body.

    • Release and remove all screws holding the Hotend fan. We need to reach a screw behind the fan.

  6. Find a M3x10 hidden behind the fan and release it slightly, few turns are enough. Our goal is to keep the parts connected.
    • Find a M3x10 hidden behind the fan and release it slightly, few turns are enough. Our goal is to keep the parts connected.

    • Repeat the same procedure on the other side of the extruder.

  7. Release and remove the M3x40 screw, the idler with the Bondtech gear will fall out. Release the other M3x40, but again just slightly to create a gap between the parts. We want to keep the entire extruder together.
    • Release and remove the M3x40 screw, the idler with the Bondtech gear will fall out.

    • Release the other M3x40, but again just slightly to create a gap between the parts. We want to keep the entire extruder together.

    • Using the smallest Allen key (1.5 mm) grab and pull the Adapter-printer part. Keep in mind there is a steel ball inside.

    • We will replace Adapter-printer part and the steel ball with a new part.

  8. Push and pull out the shaft. Keep it for later.
    • Push and pull out the shaft. Keep it for later.

    • Take out the Bondtech gear, BUT BE CAREFUL, there are two bearings inside. Don't lose them!!!

    • The printed part will be replaced with a new one.

  9. Not yet! Rewards are only for those who build a printer. Wait for the next chapter ;)
    • Not yet! Rewards are only for those who build a printer. Wait for the next chapter ;)

  10. Grab the wires of the IR-sensor cable and gently pull up, the cable should slide without significant resistance.
    • Grab the wires of the IR-sensor cable and gently pull up, the cable should slide without significant resistance.

    • Does it move? Great the test is over for now ;)

    • Don't pull hard! Ensure first that all screws are released properly.

    • Great! We are done here, let's move to: 3B. MK3S/MK2.5S - extruder upgrade

Finish Line

184 other people completed this guide.

Jakub Dolezal

Member since: 02/20/2017

222 Guides authored

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Prusa Research Member of Prusa Research

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5 Comments

I bought a Prusa i3 MK3S kit and a MMU2.0 kit all at once, because I want multi-filaments 3d printer.

I finished assembling of MK3S printer kit by ch.4 z axis, and about to start ch.5 E-axis assembly which including extruder.

When I look at the assembly procedure of ch.2B of MMU2.0 assambly (this page), I should disassemble the extruder parts.

This means after I complete the extruder assembly for MK3S kit, I have to disassemble extruder in the MMU2.0 assembling procedure.

This task seems cumbersome and wasting time.

Do you have any assembly manual for who want to assemble the MK3S kit and the MMU2.0 kit together?

I could’t find such a manual.

If you have, please let me know where.

If no, please make a manual for that.

Sang Eon Park - Reply

Hello,

You can just follow the MK3 -> MK3S MMU2S extruder re-assembly from MMU2S assembly manual.

The link: 3A. MK3/MK2.5 - extruder upgrade

Filip M - Official Prusa CS -

Suggested time: 30 min.

Tilen Thaler - Reply

I don’t know where to put my comment so i put it here.

I also bought the MK3S inkluding MMU2S, where MMU was the only reason to buy a Prusa printer.

I nearly fell off the chair when i was finished with MK3s and starting with MMU2s and i learned that i had to disassemble the whole thing again.

This is very frustrating and i woulnd’t recommend anyone to buy the printer and mmu2s until there is one document where you can build the printer immediately together (MK3S + MMU2S). I understand, that in your world there is a basic printer and there are old versions and new versions and everything has to fit. But people start now and are willing to invest the kind of money the printer costs where the USP is the mmu2s. So please spare them the history and give them one kit they can use and build.

Markus Weiler - Reply

Hi Markus,

I’m sorry about the inconvenience resulting from having to reassemble the hotend. We will look into including that information for users who build MK3S from scratch to use it with MMU2S straight after.

Marcin M. - Official Prusa CS -

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