Spring Phone Cradle - Revision 3

thingiverse

I'm in the process of creating a custom center pod in my car, designed to hold my mobile phone in landscape mode when I use GPS. I've almost completed the main pod assembly (which will be another "Thing" soon), but I needed to devise a way to securely hold my phone while driving. But how to achieve that essential grip? I know elastic bands are popular, but a car's interior environment isn't friendly to rubber bands over any period of time. They either snap at the most inopportune moment or turn into a horrible gooey mess. So I was determined to use some sort of spring. This got me scratching my head because, unless you happen to have a tension spring, you have to make a compression spring work opposite to the clamping motion if you want the device to grip the phone, and I couldn't visualize it. The solution came to me while my arms were folded, when I got an itch on the outside of my elbow. As I scratched the itch, I had a "eureka" moment when I realized that my arms were showing me exactly how it could be done: If I imagined my fingers were the spring mounts, then opening my arms would cause an imaginary spring to compress. Sorted! A quick search of my oddments tin - we've all got one - produced a couple of small springs that came from some old pens. They weren't ideal, but they WERE handy! So I designed it around them. The unit also requires 2 small bolts which will cut their own thread into the plastic. I have no idea what size the bolts are, as I found them in a drawer with some old computer parts I had lying around! What I can tell you is that the outside of the thread comes out about 2.8mm. I've attached both the STL and the Sketchup Files, so you can tweak the basic design to create more bespoke fixings for tripods, ball joints, clips, or whatever takes your fancy.