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How to replace a bowden PTFE tube (MINI/MINI+)

How to replace a bowden PTFE tube (MINI/MINI+)

How to replace a bowden PTFE tube (MINI/MINI+)
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Last updated a year ago
How to replace a bowden PTFE tube (MINI/MINI+)
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Step 1 Introduction

Introduction
Introduction
This guide will take you through the replacement of the Bowden PTFE tube on the Original Prusa MINI and MINI+.
There are two variants of the replacement:
Buy an assembled Bowden PTFE tube in our eshop shop.prusa3d.com and replace it by simply screwing it on the printer.
Assemble the Bowden PTFE tube yourself using the spare parts supplied with the printer and reused parts. Please continue in the next step of this guide.

Step 3 Removing the old PTFE tube

Removing the old PTFE tube
Removing the old PTFE tube
Removing the old PTFE tube
Removing the old PTFE tube
Release the brass nut on the PTFE print head mounting.
Remove the PTFE tube from the fitting.
Release the fitting from the heatsink.
Release the brass nut from the PTFE extruder mounting.
Remove the PTFE tube.
Don't throw anything away, wait for the next step. Some parts will be reused.

Step 5 Assembling the new PTFE tube

Assembling the new PTFE tube
Assembling the new PTFE tube
Assembling the new PTFE tube
Assembling the new PTFE tube
Place one brass nut on the PTFE tube. Double-check the orientation, it must be the same as in the picture.
Place the brass olive on the PTFE tube approximately 2 cm (0.79inches) from the end. The orientation of the olive doesn't matter. Both sides are symmetrical.
Insert the 2mm shaft all the way into the PTFE tube. The shaft must be inside the olive during the assembly like in the picture.
If you are using a drill bit, insert it with the blunt end into the tube. The sharp end can damage the tube.

Step 6 Assembling the PTFE tube

Assembling the PTFE tube
Assembling the PTFE tube
Assembling the PTFE tube
Assembling the PTFE tube
Prepare the fitting that you have removed from the heatsink. Take a look closer, there are two types of the thread. We need the side with the fine thread for the following steps.
Insert the PTFE tube into the fitting all the way in (the side with fine thread). Make sure that the inserted shaft does not fall out of the tube.
Slide the brass nut over the olive and screw it onto the fitting.

Step 7 Assembling the PTFE tube

Assembling the PTFE tube
Assembling the PTFE tube
Assembling the PTFE tube
Assembling the PTFE tube
Using two wrenches tighten the fitting against the nut. The olive inside will get pressed into the PTFE tube, which is needed for the printer to work correctly.
Release the nut and remove the PTFE tube from the fitting.
Make sure the olive is pressed correctly and does not move. If it moves, tighten the brass nut against the fitting with more force.
Insert a piece of filament into the PTFE tube from the other end and pass it all the way through in until it pushes the shaft out of the tube.
The filament must pass through the tube easily and must not get stuck anywhere.

Step 8 Assembling the PTFE tube

Assembling the PTFE tube
Assembling the PTFE tube
Use the same procedure to place the second olive on the other end of the tube. You can return to step 5, but first, read this entire step.
Before fixing the position of the second olive, make sure that both nuts are fitted correctly on the tube. The openings in both nuts must be facing out (see the arrows).
Warning: Double-check correct placement and orientation of all parts. It will not be possible to adjust anything, once the olives are squished (pressed) in the PTFE tube.

Step 9 Mounting the PTFE tube

Mounting the PTFE tube
Mounting the PTFE tube
Mounting the PTFE tube
Mounting the PTFE tube
Insert the fitting with the coarse thread into the heatsink and carefully tighten it by the wrench. Do not use excessive force!
Insert the PTFE tube into the fitting and tighten the brass nut. The orientation doesn't matter the tube is symmetrical.

Step 10 Mounting the long PTFE tube

Mounting the long PTFE tube
Mounting the long PTFE tube
Mounting the long PTFE tube
Insert the second end of the PTFE tube into the fitting on the extruder and carefully tighten the brass nut. Do not use excessive force! You can crack plastic parts.
... It's done! Your printer is ready to print.

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