Carbon fiber wheel

[PlasticGear]

Hello everyone,

I like to make lego out of exotic material, and the time has come to tackle with carbon fiber !

I made this custom carbon fiber wheel for technic cars based on the 56mm D. x 34mm rim number 49294

This is my first time dealing with carbon fiber. Wise elderly would have advise me to start with an easier part (Lego or not) but I like the challenge. So my main goal was just to make it works.

The wheel is not full carbon, I used a 3D printed insert to make the pin connections as I was not feeling it with carbon fiber. To make it real, I used a basic wet layer / 3D printed mold method, even though the mold design was not as straight forward as it appears.

The first prototype is succesfully failed. The wheel works as intended but lots of things went wrong while building it.

For exemple, the carbon fabric I used was not pre-cured, meaning the fabrics were falling appart while laying them. The mold was not well designed as some parts had to be destroyed rather than demolded. For the eagle eyeded one, you might have spot that the wheel is a mix between forged and sheets. This was not intended, I used the destroyed carbon sheets to "fill the gaps" between the pre-preg fabric as a hope for it to work, and it did the job very well despite I would have prefer a nice carbon pattern on the flange.

Unfortunatly the wheel is heavier than the lego one. A part of the mold is stuck inside the wheel, adding weight to it.

Testing were made on 1/10 car with Buwizz motors and the wheel is still standing strong !

From now I am working on a second version, much cleaner from start to end. My goals are to make a full set of lego carbon wheel, and of course, making them lighter than the lego one.

If you have any advice or question, feel free to share :)

 

If you want some insite view of the design and creation process, check out the video below :

 

edit : changed "pre-preg" for "wet layer" as suggested by JoKo

Edited July 7, 2025 by PlasticGear
changed "pre-preg" for "wet layer" as suggested by JoKo

[allanp]

Wow! I can certainly attest to how......lets say fun......it is to work with carbon fiber. Doing small parts to a high level of dimensional accuracy like this is really not easy. It might even be harder doing it with carbon fiber sheets like this. Maybe you could try a pre stabilized cloth with a finer weave, maybe like this:

https://www.easycomposites.co.uk/90g-profinish-plain-weave-1k-carbon-fibre-cloth

They also sell it in a sleeve that can expand/contract to a range of different diameters:

https://www.easycomposites.co.uk/40mm-carbon-fibre-braided-sleeve

 

Edited July 5, 2025 by allanp

[Jundis]

Geez man, is it really that hard to buy a little braiding machine like this and just braid em like a pro?

 

Kidding aside, CFK is really hard to work with when aiming for a specific and more complex shaped geometry. Hats of for trying that in such a small scale!

[JoKo]

Not bad for a first time with carbon fiber. Especially on that scale! That's my job since 2010 so, yeah, I know how hard it can be sometimes. Destroying 3D printed tooling is a pretty common last solution, don't be ashamed! 

The process you used is called "wet layup", Prepreg is a different technology not really adapted to DIY. 

Seeing the video I would have a few advice for the next version. DM if you're interested! (I speek french btw)

Edit:

there is a panel I laminated with a thin carbon layer (100g/m^2)

 

Edited July 6, 2025 by JoKo

[PlasticGear]

On 7/5/2025 at 11:29 PM, allanp said:

 Maybe you could try a pre stabilized cloth with a finer weave, maybe like this:

https://www.easycomposites.co.uk/90g-profinish-plain-weave-1k-carbon-fibre-cloth

They also sell it in a sleeve that can expand/contract to a range of different diameters:

https://www.easycomposites.co.uk/40mm-carbon-fibre-braided-sleeve

 

Thanks, I bought some pre-stabilised cloth for the next one. It will definitly be life changer.

For the sleeve I did think of it. But I wasn't feeling to use those for my first carbon part. I will give it a go when I get more confortable with the process.

On 7/6/2025 at 3:47 PM, Jundis said:

Geez man, is it really that hard to buy a little braiding machine like this and just braid em like a pro?

Hats of for trying that in such a small scale!

Of course I should make a lego braiding machine making lego carbon fiber wheel !

Thank you very much, I do feel I can get a professional looking wheel within the next wheels

[PlasticGear]

On 7/6/2025 at 7:35 PM, JoKo said:

Destroying 3D printed tooling is a pretty common last solution, don't be ashamed! 

Since I want to make 4 wheel I would prefer to keep material rather than re-priting and losting my finger sanding the mold.

I do want to DM you, but I can't since my account is too fresh. I have updated the design for the mold, and still have some doubt about how to mold the lips.

 

edit : Also, is this panel fully carbon fiber ? it looks very nice !

Edited July 7, 2025 by PlasticGear

[bruh]

Nice! One question: what would you use this for? What is its purpose as opposed to LEGO wheels? The mounting points are still 3D printed, so it’s not like the axle connection is incredibly strong. 

[PlasticGear]

Thanks, mainly free will I guess !

It is more about the look and the weight rather than the stiffness. Also the 3D printes part holds very good on lego parts

[JoKo]

On 7/7/2025 at 9:00 PM, PlasticGear said:

Since I want to make 4 wheel I would prefer to keep material rather than re-priting and losting my finger sanding the mold.

I do want to DM you, but I can't since my account is too fresh. I have updated the design for the mold, and still have some doubt about how to mold the lips.

 

edit : Also, is this panel fully carbon fiber ? it looks very nice !

Sorry for late answer. No the panel is a black Lego piece with a rectangle of carbon fiber laminated on the outside. (90gsm 1K like the first link shared bs @allanp but not stabilized). I'm happy with the pattern alinement on the piece but I sanded a bit too much which made the pattern distortion near the edges and especially near the left corner. 

About the weight of carbon fiber I'd like to point a common misconception: CFRP is not that light as a material. If you replicate a Lego piece out of carbon fiber it will be 50% heavier. So if your goal is just weight saving and look you could make the wheel 90% 3D printed and laminate the flange with carbon fiber. It would be much easier to have a clean carbon pattern. I guess it's not what you want for your youtube vidéo as it would not be legit "carbon fiber Lego wheels".

About loosing fingers in laborious sanding: Every hour spent to make the mold as smooth as possible is saved on the finishing of every piece getting  out of this mold. And of course it will make demolding every piece more easy and less hazardous for the mold.