After getting skydiving C-license I have been allowed to carry camera during the jumps (see my jump videos at Youtube). Usually small action cameras are mounted on top of the helmet but as planes have quite restricted head room the camera is constantly exposed to small strikes. Also one of the most popular skydiving helmets, Cookie G3, does not have cutaway system which would allow the helmet to be quickly removed if the parachute is tangled to the camera.
I was looking for a camera for next season and I had hoped that new GoPro would have been announced before the new year but it seems that it will be delayed past start of the season. For mounting the camera I had decided that mounts made by Grellfab would be the safest option as the camera is mounted infront of the chin and the actual camera mount has cutaway system. Unfortunately as the Gopro was not announced and all Grellfab mounts have little bit different connection to the actual camera, I could not make the order.
Frustrated I decided to order cheap Chinese action camera Xiaomi Yi (~70€ instead of ~450€ for top of the line Gopro) and to 3D print the mounting system.
During the Christmas holidays I was able to reverse engineer the Cookie G3 chin piece and design mounting system for the Xiaomi Yi. I have not had change to study Grellfabs system so I had to make few wild guesses what would make functional design.
The final mounting system has three pieces, first one is plate which attaches to the helmet using rubber bands and cutaway pin. Third is the actual camera case/housing. Main reason for three piece system (pin+plate+case) instead of two piece (pin+mount) was that I had no idea for best camera angle. With two piece design the mount would protrude much less than with the adjustable one.
Modeling was done in Solidworks and the 3D prints were ordered from Sculpteo. I made the order on 2015-12-28 and the packet arrived 2016-01-05, really quick service! I’m quite happy with the quality, only quite annoying aspect is that all surfaces have expanded 0.05mm (things which should be 3.00mm are now 3.10mm). This casuses the rotating mechanism to be too tight and I had to use sandpaper to fit the parts together. On the other hand this was expected and as now the expansion is known it can be taken into account in future models.
The models have few mistakes which makes them rather annoying to use. The skeleton case with hexagon pattern is very firm over the camera. Unofrtunately I forgot to add way to push the camera out of the case. Now you need to pull all three restraining pins and then push the camera with a screwdriver. I think that one or two restraining pins would be enough.
Second mistake was made with the cutaway pin. Screw keeping the o-ring in place should be flush with the surface but the cut for the screw head was accidentally made 1mm too small. Another 3mm hole in the pin is intended for testing the structural strength of the pin.
The rotating mechanism uses four extrusion compared to Gopros two. Originally I thought that the material (“Strong and flexible” or Nylon) would be way too flexible and would need more support but after some comparisons to Gopros mechanism I think that two extrusions might be enough (although the Gopros material is little bit stiffer).
I hope that I will have time to make necessary changes and order new batch before start of the season. I also think that I will try to make few chin mounts for friends who have helmets for which Grellfab does not sell mounting. Also if I figure how to ship the mounts cheaply I might start selling them.