PTFE tubes suitable for 3D printing and Bowden extruders

Application – scaled up and small

The PTFE tube has many applications: it has been used extensively in (large) production processes for a long time. Not surprising really, considering that PTFE is very well suited for the transfer of materials and gasses.  It’s flexible and able to transfer aggressive substances, both in very cold and very hot conditions.

Increasingly it is also found in hobby applications. A good example of an application for this material are 3D printers. The PTFE tube is used in 3D printers to guide the filament – the element used for printing – flexibly, with relative low friction, towards the (Bowden) extruder. It is therefore able to cope well with the high temperatures at the nozzle of the printer.

The most suitable diameter PTFE tube for 3D printers and Bowden extruders depends on the type of printer, the application and the filament used, but the most used diameters are:

• 1,9 mm ID x 4.0 mm OD
• 2,0 mm ID x 4.0 mm OD
• 2,0 mm ID x 4.0 mm OD Blue
• 2,0 mm ID x 6.0 mm OD
• 3,0 mm ID x 4.0 mm OD
• 3,2 mm ID x 6.0 mm OD
• 3,2 mm ID x 6.35 mm OD

For higher temperatures and even lower friction we now have also Capricorn premium PTFE tubes for both 1.75 mm and 2.85 mm filaments:

• Capricorn Bowden PTFE Tube XS — for 1.75 mm filament
• Capricorn Bowden PTFE Tube XS — for 2.85 mm filament
• Capricorn Bowden PTFE Tube TL — for 1.75 mm filament
• Capricorn Bowden PTFE Tube TL — for 2.85 mm filament 

The image below shows a typical FDM printer, now in use by many design fanatics at home. FDM is short for Fused Deposition Modelling, a classic printer for standard domestic use. Many materials can be used, but most popular are PLA (Polylactic Acid) and Butadiene Styrene (ABS). Besides, many types of filament are on the market. An example is a filament that contains wood fibre, where the printed object will have the appearance of a timber structure.

A printer of this type will print with a so called ‘filament’ – layer by layer. A motor guides the filament via the PTFE tube to the nozzle. At that point the temperature is high, approximately 200 degrees. Here the plastic melts and is sprayed onto the print. If you look closely at a 3D print you can distinguish the layers from each other. In general, the thinner the layers are, the more beautiful the print is.

The PTFE tube is therefore crucial in guiding the filament. Without such a tube the printer is of no use. It ensures that the filament is under constant pressure from the extrusion motor and can only progress in the direction of the nozzle/Bowden extruder.

Nowadays we can find several variants of standard FMD printers. A dual-extrusion printer is an example. Here the nozzle has two entrances, which allows for printing in two materials or colours. Ideal if you want to give parts of your print different material characteristics.

Outside the use of PTFE tubes in printing, it can also find excellent applications in hobby projects. PTFE tube is indispensable in the following project, the track of a 3D printed rollercoaster!

3D printed rollercoaster – Giant Inverted Boomerang

Two years ago, I embarked on the design and construction of a 3D printed rollercoaster. My aim was to build a fully functioning model. I love rollercoasters and enjoy 3D design, so this seemed the ideal project to bring these two interests together.

And so it happened, in the summer of 2019 I started with the 3D drawings of an existing rollercoaster model: the Giant Inverted Boomerang. This type of rollercoaster, although designed and produced in the Netherlands, can be found across the globe! A smaller sister of this design can be found, for instance, in the Flevopolder: Walibi Holland.

For a while the 3D printer was working long hours and section after section rolled off the production line. Once the full structure was almost complete it was time to give some thought to the tracks. After all, a train will have to roll with ease and little friction across these. Globally, several 3D printed rollercoasters have been built and I noticed that PTFE tubes were used regularly to shape the rails.

My choice, therefore, not unexpectedly, was also for PTFE tubing. Because PTFE Tube Shop can supply at reasonable prices and in any size, this was where I ordered my tubes. The image below shows part of the rollercoaster, where the PTFE tube is mounted onto the structure.

After a partial installation of the PTFE tube, the project looked as follows:

Now it is the turn of the electronics and the train to be constructed and installed. In a few months I hope to have a fully functioning 3D printed rollercoaster, with a little assistance from the PTFE tubes.

Patrick de Groot