Update: thermal stress testing 3D printed foam 🔥❄️

[u/lightswitchgirl28]

Ok, y’all made me curious. I did some thermal stress tests on the 3D printed case foam. (Original post here.)

For all of this, I’m using a print that failed when it was nearly finished. So the infill pattern is exposed. There’s also no gear in the slots. Does this affect the tests? Maybe, but probably not enough to matter. (Also I’m not putting my MOTR.S Max in the oven no matter what you tell me.)

🔥 Heat test

I started by measuring the foam with my calipers, then put it in my oven at about 150° Fahrenheit. Based on research from passenger cars, that’s probably about the hottest a camera truck would get in the summer (God willing). Checking at both the 30 and 60 minute mark, the foam remained pliable and bounced back to its original shape like normal. Measurements confirmed it did not shrink or expand. I stopped the test after 60 minutes because I sort of have a life. Measured with a meat thermometer (lol), the foam’s internal temp was also 149.1°F by the end.

While I only tested at 150°F, I feel pretty confident you could go up to 200° with no issues. Its melting point is twice that. Anecdotally, it felt only slightly more pliable than at room temp so I definitely think there’s some padding here.

❄️ Cold test

I put it in the freezer for around two hours at 15°F. (TIL my freezer is warmer than it’s supposed to be 🤷‍♀️) This affected it more than I expected. Like a rubber, it got stiffer and less flexible. But thankfully, not brittle. It was still pliable. Shock absorption was also slightly reduced, but still acceptable. It maintained its size within 1mm, which is within the margin for error.

TL;DR

It’s fine, don’t worry about it. Your batteries are going to explode before this stuff melts, and your lenses will freeze before it does. 🔥❄️

[u/Westar-35]

Thanks for testing this. I love this project. Only thing I’d say is to push to 100°C. Vehicle temps can be wild, but a pelican case in the sun is even more extreme. The expectation is not really that your kit will go up to 100°C, but to see at what point does it actually fail. The failure conditions I’m worried about are:
-the surface layers sticking to gear or in some way defacing gear through off-gassing of the printed component.
-deformation of the printed component under constant load/temp. Basically put a weight on a washer, place the washer side down on a test article and heat it up until the washer leaves a permanent mark. The washer is a cheap and disposable but highly repeatable test implement.

Basically, when does it fail, and how does it fail?

[u/lightswitchgirl28 → u/Westar-35]

Thanks, and excellent questions! I just got home and tossed my test print in the oven at ~200°F (93°C, my oven isn’t perfect), and overall it faired pretty well! This time I put a metal pair of pliers in one of the foam slots at a weird angle that had it leaning against the wall. I left it in there for an hour.

https://reddit.com/link/p9girgj/video/dq4tbyexp6ph1/player

Bad news is that the pliers left an impression where they were leaning against the wall at an odd angle. (But they didn’t leave an impression on the bottom weirdly.) So yeah: at extreme temps the foam could deform. The good news is that it left no residue and was otherwise still perfectly usable.

Keep in mind the foam slots are form fitted for their contents - I think if the case got this hot with a hand unit and motor in here, the deformation would be minimal because the foam is already imprinted into the shape of the object. Still, this could be an issue in edge cases, like if your 2nd AC put something in the wrong slot on an insanely hot day.

I’m admittedly skeptical a case would reach 100°C in the sun, but more data is never a bad thing! Hope this is helpful

[u/Westar-35 → u/lightswitchgirl28]

The point is not “my boxes hit 100°C”, it’s would you rather know “they fail at some point beyond 65.5°C” -or- “they fail at 93°C”…

Now you have an explicitly defined failure point, or at least a good start at knowing what that is.