Mendel: Prusa durable z-axis motor coupling

This is a design for a new, more durable flexible coupling (http://en.wikipedia.org/wiki/Coupling) for use on the z-axis motors in the Mendel: Prusa RepRap machine design. The design allows for 2-3 degrees of play, but can be adjusted depending on how it's machined.

Please see the following YouTube link that shows the an animated CAD simulation of the design:
http://www.youtube.com/watch?v=PQEHnb5eVaE
and here is the design manufactured and in use:
http://www.youtube.com/watch?v=Hu32DFF1TX