During my head movement tests, I found that the side to side axis (the azimuth movement) was binding. I stopped by the hardware store to find a bearing, but nothing was appropriate. So, time to build my own.
I found this patio door roller with bearings that's the perfect size. Add in a couple of flat end caps that fit the PVC bones of the neck, and I'm ready to put together a smoother joint.
I'd been having some problems with the springs and the S connectors slipping off when moving to the limits of motion. I decided to add some washers to the bolts holding the springs, and crimp down the openings on the S connectors.
I also decided to glue together several of the PVC pieces that make up the neck to keep them from slipping and provide some additional support. Bring out the PVC adhesive!
I put the costume back on to see how all of these little improvements affected the movement. It was much smoother and more "solid". By that I mean the springs didn't rattle around, but maintained a level of tension that kept the pieces firmly attached to the joints. However, the new joint raised the steering bar higher up from the base support, and that had the effect of reducing the range of motion, as well as making the horizontal part of the neck thicker. I'm pretty sure some lever arms added added between the steering bar and the cross piece at the end of the base structure would solve both problems, but I'll wait to tackle that improvement until the next time I work on this costume. I'll also try to illustrate the geometry of the mechanism a bit better so that it's clear how I can reduce the neck thickness and get a bigger range of motion mechanically.
Today I received the silicone rubber I'll be using for eyelids and the overall skin coat. But, there's a lot more foam work to do, as well as the eye movement and blink actuators. I'll be taking a break on this cosplay until after San Diego Comic-Con in order to get things ready for that show.
Because, you know, it's COMIC-CON!