Carbon Fiber Reinforcing 3D Prints

The Problem

3D prints are generally on the brittle side. Especially under tension between the layers. A brilliant way to get around this is to use flexible filaments. TPU, PP etc. These filaments are especially popular in the FPV world where they are used to mount cameras, protect electronics and often form the main cover of the frame.

These filaments are incredibly tough (able to absorb large amounts of energy before breaking) however they typically have a very low stiffness. Parts that you might need to be rigid are a little floppy. And despite having much better inter-layer adhesion, they can still be ripped if bent far enough over against the layers.

Granted, this example needed pliers. But I’ve broken a fair number of things out in the field

The Solution

I’m sure I’m far from the first person to do this but I’ve also yet to see anyone else write about it. For a while now I have been reinforcing my prints with Carbon fiber (CF). CF in 3D prints is nothing new. There are several filaments available with small strands of CF. Unfortunately these contain very short lengths of fiber, which hardly provide the true benefit of CF.

In my version, I purchased some CF rods/spars. These are available from eBay and I’m sure many other places for very reasonable prices in a range of lengths and diameters. I mostly use the 2/3mm variants.

The Method

This works best if you have designed the part yourself but the changes are not difficult to retrofit into imported data.

Step 1

Cut some cylinders into your model:

This works best if you start designing with the intent to add them, making sure there is enough thickness of material to support them.

The reinforcement works best across layers, where the print is weakest, consider what orientation the part will be printed in.

Step 2

Cut some CF to length.

I typically use one of these precision hobby saws

CF is pretty nasty stuff, wear gloves if you can and a face mask if there’s likely to be any dust.

Step 3

Wedge it in there

Again be careful of CF splinters, don’t push directly with your hand. Push the CF into the holes you cut and your’e good to go. Simple as that.

Step 4 (Optional)

Use it for every thing. This is more of a PSA that these CF spars exist and are easy to design and work work with. Try putting them in normal prints, use them instead of thin walls, go wild.