Printing large parts with TPU on a 3D printer

Everyone that tried printing TPU before knows it’s not an easy material to print with. It absolves air moisture pretty quickly and it has a passion for staying clogged on your hotend.

There are a lot of YouTube videos showing strategies to print on TPU, but they normally focus on small print parts, with a few hours at most.

Printing for more than a day

For big pieces, like these wheels, I created for my backhoe, the quickest one printed in a day and one our. The rear wheels took more than three days to print!

The problem I was having occurred sometimes right after the beginning and sometimes only after 10h or so, which made me sad a couple of times.

If everything looks good, this is what you’d expect to see:

My 3D printed wheel and its TPU tire and a good Brazilian bananas for comparison :)

Quick tips that worked for me

1. Always use hotends with a PTFE tube inside for TPU prints.

Here I found a good explanation of why it worked for me:

Most of the existing resistance during feeding comes from the friction between the filament and the filament tube’s inner wall. All-metal hotends generally have a feeding tube with an internal metal surface that is not polished. On the other hand, the metal has good thermal conductivity and rapidly absorbs heat from hotend. High temperature tube causes thermal expansion of the TPU filament, which further increases feeding friction. Following image shows an old type all-metal hotend structure.

This was by far the most important change I needed to make on my 3D printer.

2. Yeah, you really need to print slowly

You probably heard about it before, in my case, 30mm/s is a good limit.

3. Dry out your filament

You want to avoid this:

TPU absorbs humidity super easily, so if you’re looking for great print quality, it’s important to have it inside a chamber to remove its humidity. I still don’t have it, so I use my 3D printer bed closed with cardboard to make the process. It’s not perfect but helps a lot!

More about drying your filament here.

4. Customize your settings according to your printer

Here’s a great video showing how to improve your printer settings by printing some reference pieces and calibrating them.

Although the guy from that video recommends 0.6mm nozzle, I’m having great results with my default 0.4mm.

These are the settings that worked for me on Cura. Feel free to try them out if you want.

Downloads: 63

Some funny photos of my attempts

All of these were attempts to print a 22cm x 7cm rear tire, which was super hard to achieve. So my main tip is: try be resilient!

Here I’m sharing 11 attempts of printing with different configurations and strategies. All failed and some only failed after 12 hours of printing.
Used some of them as temporary wheels for my backhoe
The first 12 hours seemed to be good enough but turns out I was wrong
My printer was still thinking it was printing correctly, 10 hours :O

I took the opportunity of failed printings to improve the design. On the right is my first wheel rear design, on the left is the final design: bigger and with more creases.

My backhoe just waiting for the rear Tires which were super hard to print

Some tips for printing big tires on TPU

Use some infill, I used 5%. Also, the wall thickness should be at least two lines, but three would give more strength.

Finishing a tire print with TPU.

References

https://www.raise3d.com/academy/how-to-choose-a-better-printer-for-tpu-printing/
https://www.youtube.com/watch?v=lD9Ei3u5-iU
https://www.youtube.com/watch?v=WC3jvuq-uq8

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