3D printed motorcycle

[harrisonpatm]

Selfish plug: I'll point out that Ryan specifically mentions an FDM brake lever made from PA-CF, and that it can be made stronger, cheaper, and lighter than a cast aluminum brake lever. Same as the 3d-printed brake lever on my motorcycle!

And if you go to the end of the video, you'll see that he broke an aluminum part of the hub motor itself doing jumps. Nothing 3d-printed broke.

I'm still not too hot on hopping on a fully 3d-printed motorcycle...

 

[bananu7]

Selfish plug: I'll point out that Ryan specifically mentions an FDM brake lever made from PA-CF, and that it can be made stronger, cheaper, and lighter than a cast aluminum brake lever. Same as the 3d-printed brake lever on my motorcycle!

Perhaps with continuous reinforcement and major shape alteration, but I don't think Nylon + short carbon strands can realistically outperform aluminium on a stiffness-to-weight criterion even if you designed a heavily optimized shape for it.

This is perhaps the best reference for it I know of:


Source: Replacing Aluminum Parts with 3D-Printed Carbon Fiber

I know PA+CF has about half of the density of aluminium, theoretically allowing much stiffer shapes by making them much larger physically (and empty inside!), but there's a huge stiffness gap of the material itself. Of course, once you start adding continuous strand composite reinforcement, it all flips on its head.

I would be very interested to be proven otherwise, as my experimentation clearly shows

 

[ProEV]

I had never heard of Onyx. It looks like an interesting material to print in. It seems another question is loss of strength from humidity over time. This paper claims "a specimen absorbs approximately 2% of the humidity and loses up to 65% of its Young's modulus after 165 days of exposure, significantly influencing the mechanical properties of the parts. Consideration should be given to this aging of onyx when using printed parts as structural parts." That sounds like it would be an issue.

 

[ProEV]

Forgot to include the link:

https://www.sciencedirect.com/science/article/pii/S2772665723000144

 

[bananu7]

The biggest selling point of Onyx, or the entire Markforged portfolio, is the CFR, continuous fiber reinforcement. The plastic effectively takes the role normally occupied by epoxy or polyester resin, bonding the strands together and acting in compression, while the fibers take the tension loads.

Regular Onyx on its own is comparable to Nylon.

 

[Hillhater]

This paper claims "a specimen absorbs approximately 2% of the humidity and loses up to 65% of its Young's modulus after 165 days of exposure, significantly influencing the mechanical properties of the parts

But wouldnt Aluminium also lose some of its mechanical properties after 165 days, if exposed with no treatment/protection ?

 

[ProEV]

I did a quick check with an AI and was surprised to learn this was true. I could not get the AI to give me some idea of how big a loss or how quickly it occurs. It is different for different formulations of aluminum but does not seem to be a greater problem for 3D printed aluminum.