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  1. This guide will take you through the entire process of how to disassemble the MK3/MK2.5 extruder, replace the PTFE tube and assemble the extruder back. This guide doesn't work for the MK3S, MK2.5S or MMU2S type of extruder !!! Please follow: How to replace PTFE tube on the MK3S/MK2.5S/MMU2S
  2. Please prepare tools for this chapter:
    • Please prepare tools for this chapter:

    • 2.5mm Allen key for M3 screws

    • Needle-nose pliers for zip ties

    • Apart from the mentioned tools, it is recommended getting a bowl or small box for the screws and parts you will remove during the disassembly, you will need them later.

  3. Ensure the filament is not loaded in the hotend. Remove it before proceeding further. Make sure the printer is cooled down properly!
    • Ensure the filament is not loaded in the hotend. Remove it before proceeding further.

    • Make sure the printer is cooled down properly!

    • For the following steps, please prepare:

    • PTFE tube for MK3/MK2.5 (1x)

    • Zip tie 2.5x100 mm (2x)

    • The length of the zip tie can be slightly different. The width 2.5 mm is recommended due to the printer's design.

  4. Release marked M3 screws. Remove the fan-nozzle completely.
    • Release marked M3 screws.

    • Remove the fan-nozzle completely.

    • Carefully insert the Front print fan in the X-axis belt.

  5. Release and remove all four M3x18 screws on the Left hotend fan. Release and remove both M3x25 screws, then remove carefully the extruder-cover part. Your extruder and fan arrangement should look like in the last picture.
    • Release and remove all four M3x18 screws on the Left hotend fan.

    • Release and remove both M3x25 screws, then remove carefully the extruder-cover part.

    • Your extruder and fan arrangement should look like in the last picture.

  6. Turn the printer around and cut two zip ties on the heater cables. Be very careful while cutting!
    • Turn the printer around and cut two zip ties on the heater cables. Be very careful while cutting!

  7. WARNING:  Removing hotend from the extruder needs a "special" technique, then the hotend slides out quite easily. Don't use excessive force, or you will damage some parts irreversibly!!! The hotend is removed by inclining and pulling at the same time. See the first picture showing the WRONG inclination. This hotend is inclined too much to the front and there is no gap between the hotend and the extruder body. Hotend is partly inside and you won't be able to remove it. The second picture is showing the CORRECT inclination. The hotend is tilted, but there is a gap between the hotend and the extruder body. You will be able to remove it.
    • WARNING: Removing hotend from the extruder needs a "special" technique, then the hotend slides out quite easily. Don't use excessive force, or you will damage some parts irreversibly!!!

    • The hotend is removed by inclining and pulling at the same time. See the first picture showing the WRONG inclination. This hotend is inclined too much to the front and there is no gap between the hotend and the extruder body. Hotend is partly inside and you won't be able to remove it.

    • The second picture is showing the CORRECT inclination. The hotend is tilted, but there is a gap between the hotend and the extruder body. You will be able to remove it.

    • Now, let's incline the hotend properly. Take pliers in the second hand, grab the hotend above heatsink's ribs, pull downwards and slightly towards you. The hotend should "jump" out. Make sure you don't stretch the cables too much or you might damage them.

  8. Press the black plastic collet.
    • Press the black plastic collet.

    • Remove the PTFE tube from the hotend.

    • Throw this old tube immediately to the nearest trash bin to avoid installing it back by accident ;)

  9. Now it is time to insert the new PTFE tube. Note there are two different ends. One end of the tube has "rounded" outer edge. This end must be inside the hotend.
    • Now it is time to insert the new PTFE tube. Note there are two different ends.

    • One end of the tube has "rounded" outer edge. This end must be inside the hotend.

    • Look at the other end, where the tube is drilled inside, shape of the edge is "conical". This is the side, where filament enters the tube. This part must be outside the hotend.

    • Push the black collet in. Slide the tube all the way in and hold it!

    • Using second hand pull the collet out and only then release the tube!!! THIS IS CRUCIAL for the hotend to work properly.

    • After you finish inserting the new PTFE tube, check all the parts are properly tightened and nothing got loose during the process.

  10. Carefully slide the hotend back to the extruder-body.
    • Carefully slide the hotend back to the extruder-body.

  11. Insert the zip ties in the slots of the cable-holder.
    • Insert the zip ties in the slots of the cable-holder.

    • ATTENTION! Before tightening the zip ties add the cables from the hotend.

  12. Move back to the front side of the printer. Be careful while assembling the extruder! Make sure you don't pinch any wire (e.g.  P.I.N.D.A. cable).
    • Move back to the front side of the printer.

    • Be careful while assembling the extruder! Make sure you don't pinch any wire (e.g. P.I.N.D.A. cable).

    • Assemble back the extruder-cover and tighten both M3x25 screws.

    • Guide the motor cable back in the slot.

  13. Move back the Left hotend fan and tighten all four M3x18 screws. Tighten carefully, you can crack the plastic frame of the fan. Place back the Front print fan and the fan-nozzle. Tighten all three screws. Proceed carefully, you can crack the plastic frame of the fan.
    • Move back the Left hotend fan and tighten all four M3x18 screws. Tighten carefully, you can crack the plastic frame of the fan.

    • Place back the Front print fan and the fan-nozzle. Tighten all three screws. Proceed carefully, you can crack the plastic frame of the fan.

  14. Great job!
    • Great job!

    • Heat up the printer and try it out ;)

Finish Line

20 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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364 Guides authored

11 Comments

Note: My cable holder is original from my Mk 2S and I did not get a different one when I got the Mk 2.5 upgrade kit. The one pictured in steps 6 and 11 are significantly different (note holes for ties).

Merrill Albury

Merrill Albury - Reply

Hello Mr. Albury,

I confirm that the cable holder part is different, you have to print and use the one included in the 2.5 printable parts package. The one used for MK3 would not allow the extruder to click the endstop.

Martin L. - Official Prusa CS -

In STEP 1 there are two disclaimers which seem to contradict. I have a MK3 Extruder and based on the disclaimer i can’t decide if this is applicable to me or not

DISCLAIMER 1 - This guide will take you through the entire process of how to disassemble the MK3/MK2.5 extruder, replace the PTFE tube and assemble the extruder back.

DISCLAIMER 2 - This guide doesn't work for the MK3, MK2.5 or MMU2S type of extruder !!! Appropriate guide will be published soon.

Shiv - Reply

Hey Shiv, good catch. We’ll fix it asap.

Filip M - Official Prusa CS -

Hi Shiv, thanks for noticing, there was a typo. This guide works only for older MK3/MK2.5 extruder design. For the MK3S/MK2.5S/MMU2S there will be new manual.

Jakub Dolezal -

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