Some excellent progress with prototyping over the past few days.
After a few iterations I have a hub prototype that is working quite well. The SketchUp model of the hub is available here.
Here is a short movie that covers my progress to date.
For anyone wanting to experiment with this design, here are some specifics about the parts I'm using.
The balls are 1/2" diameter plastic of various types (still experimenting). I obtained these from www.usplastic.com. (Item #s 091506, 091517, 091561)
The 8/32 Nylon threaded rod is also from US Plastic Corp.. (Item # 091841)
The 1/4" clear acrylic tube is from TAP Plastics. (Item # 23183)
The rod inserted into the tubes is 1/8" diameter aluminum.
Next step is get more efficient at producing the units. Will provide an update on this in a couple of days.