A few years ago I bought a DJI Osmo Action camera, similar to the GoPro line.
After searching for 3rd party chin mounts, I decided to design my own. Here's how I went about it, from measuring the helmet to CAD design to printing options and finishing.
I used a contour gauge to capture vertical and horizontal sections of the chin of my helmet. I captured the curves, then took carefully aligned pictures that included the gauge's ruler for later scaling in CAD.
I use Autodesk Inventor, software I work with every day doing that what puts motorcycles on me dinner table.
I inserted a photo into CAD, scaled to actual size, created a spline curve of 1/2 of the profile, then mirrored it. The curve doesn't quite match the contour gauge, as I had to fine-tune the shape until the fit was good enough.
Created the helmet mating surface by
sweeping the curve above, here shown in red, along the vertical arc, shown in green:
Created a
shell of the mating surface 1/8" thick:
Trimmed so the front view of the mount is an oval:
This short riser...
... provides a base for a
loft, which blends the mount into a stronger shape in the center:
The beginnings of the GoPro-style clamp:
Blending makes it purdy but also stronger:
Clamp features complete:
Some final tweaks and the CAD work is complete:
I initially printed a few prototypes using a typical FDM consumer-type 3d printer, used to adjust the fit.
I ended up getting the model professionally printed in an SLS process: selective laser sintering, where a bed of powdered glass-reinforced nylon is melted with a laser layer by layer. This produces a very strong part, though the surface is a bit rough and porous. After finish-sanding with cloth backed 220 grit, I went straight to rattle-can white enamel paint, letting it dry 24 hours before sanding and recoating. I gave it four coats and let it dry a few days.
Final attachment was using clear Gorilla mounting tape. It's not perfect, but for a kid who never liked to paint his plastic model cars, it didn't turn out too bad.
