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How to replace a PTFE tube (MK3/MK2.5)

How to replace a PTFE tube (MK3/MK2.5)

How to replace a PTFE tube (MK3/MK2.5)
Relevant for:
Last updated a year ago
How to replace a PTFE tube (MK3/MK2.5)
 Difficulty
Moderate
 Steps
14
 Available languages
CSDEESFRITPL

Step 1 Getting the correct PTFE tube

Getting the correct PTFE tube
Getting the correct PTFE tube
Getting the correct PTFE tube
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 a hotend PTFE tube (MK3S+/MK3S/MK2.5S/MMU2S)
To obtain the new PTFE tube you have two options:
Buy cut and chamfered PTFE tubes from our eshop
Make your own PTFE tube using this guide: How to trim PTFE tube - Original Prusa printers

Step 2 Tools necessary for this guide

Tools necessary for this guide
Tools necessary for this guide
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.

Step 3 Preparing the necessary parts

Preparing the necessary parts
Preparing the necessary parts
Preparing the necessary parts
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.

Step 4 Extruder surgery (part 1)

Extruder surgery (part 1)
Extruder surgery (part 1)
Extruder surgery (part 1)
Release marked M3 screws.
Remove the fan-nozzle completely.
Carefully insert the Front print fan in the X-axis belt.

Step 5 Extruder surgery (part 2)

Extruder surgery (part 2)
Extruder surgery (part 2)
Extruder surgery (part 2)
Extruder surgery (part 2)
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.

Step 7 Extruder surgery (part 4)

Extruder surgery (part 4)
Extruder surgery (part 4)
Extruder surgery (part 4)
Extruder surgery (part 4)
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.

Step 8 Removing the old PTFE tube

Removing the old PTFE tube
Removing the old PTFE tube
Press the black plastic collet down towards the heat sink.
Remove the PTFE tube from the hotend.
Throw this old tube immediately to the nearest trash bin to avoid installing it back by accident ;)

Step 9 Assembling the new PTFE tube

Assembling the new PTFE tube
Assembling the new PTFE tube
Assembling the new PTFE tube
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.

Step 11 Extruder reassembly (part 2)

Extruder reassembly (part 2)
Extruder reassembly (part 2)
Insert the zip ties in the slots of the cable-holder.
ATTENTION! Before tightening the zip ties add the cables from the hotend.

Step 12 Extruder reassembly (part 3)

Extruder reassembly (part 3)
Extruder reassembly (part 3)
Extruder reassembly (part 3)
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.

Step 13 Extruder reassembly (part 4)

Extruder reassembly (part 4)
Extruder reassembly (part 4)
Extruder reassembly (part 4)
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.

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