This is a bike handlebar mount for the Garmin eTrex 10/20/30 series of handheld GPS devices. Given that many other newer Garmin GPS devices (such as Colorado, Dakota, Oregon...) also seem use the same type of slide rails, I guess that this mount could probably be used for all those as well - but since I only have a eTrex 20, I don't know for sure...
The corresponding bike mount sold by Garmin uses cable binders to attach the mount to the handlebar - I don't really like that... My mount has a hinge so that it can be easily opened up when attaching it to the handlebar.
Two bolts are needed to assemble the bar mount: An M3x25mm with a corresponding nylon nut serves as axis for the hinge and a M4x25mm bolt is used to fasten the bar mount. The corresponding M4 nut fits tightly into the hexagonal cutout. I use the tip of my hot soldering iron to push the nut in firmly, so that it will never fall out again.
The SCAD file provided is parametrized so that it can easily be adapted to specific handlebar diameters. Also the eTrex specific parts are separated in special modules, so that the bar mount clamp part can used for other types of clip-on systems.
As this is actually continuation of my earlier bike handlebar mount for for the older eTrex Legend/Vista C/Cx/HCx series (http://www.thingiverse.com/thing:163503), the SCAD file still also supports the slide rails for these older devices. Given that the auxiliary bridge support structure was greatly improved since my first version, I also include updated versions of the STL files for the older eTrex series.
STL files are provided for handlebars with a diameter of 22mm, 25mm and 28mm - a range which should pretty much cover most of the more common bar diameters.
Given that the two parts of the hinge are not self-supporting, I added 6 narrow stripes as "bridges" underneath the hinge parts. These need to be cut with a knife after printing to separate the two parts.