Monday, April 16, 2018

Carpc project - the case

I recently uploaded a new video to show my custom-made carpc based on a Raspberry Pi. In the video, I had to leave a lot of information out for the sake of runtime, so, I decided to write a little series of posts to explore thoughts and ideas about this project.

This episode is about the case.

Disclaimer (sort of):
Be aware that this post is not self-contained. If you haven't seen the video, you probably won't get much out of this reading. Also, this is not a tutorial on how to build a carpc like the one I made. For that, I'd need much more time and space. I just want to document the thought process behind a few hardware and software choices, share some techno-ramblings, and provide you with some links to get you started using the components I used.

Have you ever modified your car with custom electronics? Are you planning to hack a Raspberry Pi into a device that was not intended to be modified? Have you ever started a simple project (such as adding music to your car), and somehow turned it into a huge, titanic undertaking?

The case

 

Final design files.
And then it hit me.
With this project, my car will become a wild mess of tangled wires. Shaking my head in horror, I decided to do something about it, and design a custom 3D printed plastic enclosure for the carpc.

Now, I'm not an industrial designer, so this case design required a good dose of improvisation and trial and error. I also fought fiercely against the (small) tolerances of the 3d-print shop, and discovered with great disappointment that designing a 12.5mm wide part does not mean the part will be exactly 12.5mm wide. This realization bit pretty hard the moment I started designing parts to be slotted into one another. Experience, experience...

3D-printed case parts.
So, In order to take measurements and get the proportions right, I've made a crude mock-up in paper (actually, SEVEN crude mock-ups in paper. It's amazing how often a millimetre can make the difference between two parts aligning with each other and one part ramming itself into the other one...). Then, I had to choose a 3D CAD to input my final design. Being a complete noob in this field, I faced quite some problems in becoming proficient in any of the popular CADs for Linux, from FreeCAD (still a mystery to me) to Blender (full-featured, but with a steep learning curve). In the end, I settled on Sketchup, and designed the whole thing under Windows, starting from a single rectangle and extruding the entire structure volume by volume. I'm sure this is not how it's done, but the result holds in place, so I call it a success.

PS: I had to shave a few millimetres off the corners of the base to make it fit the ash tray cavity, because no matters how accurate your paper model is. It isn't.

Have fun,
Kradion.

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