I am woking on making solar panel mounts for the roof rack of my nissan xterra from TPU, since it can take a beating. Does any one have any experience with 3d-printed TPU threads? And how much stress before it can take before a bolt rips out? Also should i use teflon thread seal so the a bolt won’t come loose?
I would through bolt the TPU and use a large washer on each side. Teflon lubricates the threads making it easier to turn. You want thread locker to keep a bolt from coming loose. Be careful with the thread locker since it eats many types of plastic.
Agree with all of this. Relying on the walls of TPU to hold threads in place doesn’t seem like a great idea.
Yup, assuming the solar panels will be in the wind, potentially at highway speeds, absolutely do not rely on TPU threads for that. Threads rely on stiff material to transmit the forces from the angled faces of the thread into linear forces. Anything flexible will rip out very easily. It’s shocking how fast a rubber material - even a firm rubber - gives up when real force is put onto it. It’s like it’s not even there.
The through bolt idea is pretty good. It should be easy enough to make a spool shape out of the TPU that will work as a shock absorber. Honestly even then I’d keep an eye on it to make sure it’s not getting ripped up.
EDIT: I was curious how to quantify the difference, so I found this datasheet which shows the difference between the stiffness of rubbers, particularly polyurethane, which is what TPU is, and steel:
https://www.ansys.com/content/dam/amp/2021/august/webpage-requests/education-resources-dam-upload-batch-2/material-property-data-for-eng-materials-BOKENGEN21.pdf
You’re looking for Young’s modulus, which is 1.3 - 2.1 GPa for polyurethane, and 190-220 GPa for the various steels. Steel is hundreds of times stiffer. And for the threads to fail, they don’t need to be damaged, just shift out of the way enough to slip past each other.
Not to mention 3D threads will not be the right cross-section. It won’t be face to face contact.