I’ve been working on an interesting project with a fair bit of design and printing work that I thought that I’d share here. It’s based on the RMS opensource meteor camera project that I’ve shared in the past, but modified for LEO satellite tracking. Normally, we operate in accessible locations with temperatures typically between +30 and -30 C, but this deployment to Eureka (+80N) presented some neat design challenges for 3D printed parts. First, it’s typically cold (-35 C in the winter with a record of -68 C!). Second, it’s often windy and there can be a lot of frost (even though it’s an arctic desert). Because of this, I was really uncertain about choosing a filament (I couldn’t find much info on material performance under these conditions), but, in the end, I printed most parts with ASA (3DPC house brand and Spectrum ASA275). Some parts were printed with PETG (3DPC PETG+), but these were all static with small loads. PETG has never given me a problem down to -40, but I’m not sure what happens at colder temps. For ASA, I’ve found references to using it at temps below -100 C, but not in the context of FDM filaments. Past field experience has shown that just about everything seems to break at -50, even when it shouldn’t. I’d be curious to know if anyone else has experience with different filaments at very low temps. Could delamination failures be a problem?
Here are some pics of the cameras…
The astute observer will notice that I used different colours of ASA for the larger housings. The main reason for this was the lack of white 3DPC ASA a few months ago and I happened to have some natural coloured ASA waiting to be used. The parts are all printed with 50% infill and I’ve used silicone o-rings (red) and custom-molded silicone gaskets (blue) to keep things water tight. I also designed a double-glazed window for the front of the larger cameras, but they’re not installed here. The hope is that there is enough internal heat clear the windows of frost. Fingers crossed that it lasts a season!
The big housings also have an odd lens mount (M34, I think) so I had to design an adapter for mounting it to the sensor module. These, I print with Siraya Tech Sculpt resin since it has a high temperature resistance (the modules get quite hot). The adapters also have slots for a 10 mm micro stepper which we can use as for remote focusing (controlled by a Pico W). The gears for the focuser are printed with Spectrum S-Flex and it works well over WiFi. Comments on resins that are dimensionally stable at temperatures up to +70 C are appreciated.
Any thoughts on designing/prototyping/building for extreme environments like this are welcomed. I’ve learned a lot from this project, but I know that there’s a lot to still learn.
And, to give you an idea of how crowded the skies are with satellites, the next image shows a stack over an entire evening of observations (from the London area) with a single camera.
Have fun!
Mike
FWIW, I print the 3DPC ASA on a Troodon with a textured bed, the Spectrum ASA and S-Flex on an FLSun QQ-S Pro (modified for direct drive) with a PEI plate, and the resin on an Anycubic Mono. Nothing fancy, but it all works well.