Step 8: Attaching the Cradle to the Mount
I placed the two neoprene faced washers metal to metal. The nylon washers' inner diameter was slightly bigger than the metal washers' outer diameter. I placed three nylon washers on the outside of the two neoprene faced washers, then ran my shoulder bolt through the holes. See the diagram for a visual on this.
The metal washers provide the majority of the friction required to keep the phone from rotating freely. I tried it without the nylon at first, but it had a slight wobble that I was not happy with. After I added the nylon washers, they provided a lot of stability and made the wobble go away.
It is IMPORTANT to use thread lock on the shoulder bolt. If you don't, repeated rotation from portrait to landscape will back out your mounting screw. You can find thread lock at a home improvement or hardware store...it is expensive (about $8 for a tiny tube), but you only use a drop here and a drop there, so you can use it on future projects.