## Thursday, July 3, 2014

### Helmet camera mount

I bought Mobius ActiveCam cemara. Quite good device, but unfortunetly mount is not enought good for helmet curvature.
I thought about making mount on 3D printer, but to do this i need model of helmet.
To do this job I make simple device: spherometer, which allows me to mensure radius of helmet curvature. My project for printing is ready to print and avaliable here

Spherometer works very simply. You know the dial indicator displacement (h) and distance between leg (R, in my case 30mm), you can calculate sphere radius (r), according to the formula:
$r= \frac{R^2 + h^2}{2h}$

Before mensure i make net with electrical tape, and mensure radius only in intersections.

With the help hand of spreadsheet I mensured radius for every point. The maximum difference was about 10mm, so i assumed that helmet is ideal sphere which radius is equal to average of all mensurment radius. Next think is only make drawing, and print it.

Element was glue with double side 3M tape to helmet. Tape is quite thick and idealy fill the space between elements.

It is not a problem to fix the camera to flat surface of mount using the orginal attachment. The type od fix was riding with me for about 4 months (3000km) and there wasn't any problem with it. Disadvantage of mount is that i can't push buttons with the helmet on, no lens protection against insects and also light whiz when i ride without camera with speed above $>90 \frac{km}{h}$.
There is also a problem with power connection. Battery last for 80 min and cable connected to helmet is a additional problem.
Now i change my helmet to more aerodynamic so i plan to fix camera behind fairing.