Smooth rod / shaft collar from a drilled out M8 nut

This is part of an audit of the Prusa Mendel to improve stiffness and reliability.
Other byproducts of those concerns:

http://www.thingiverse.com/thing:11017
http://www.thingiverse.com/thing:10994
http://www.thingiverse.com/thing:15606

There is ancestry for this thing in Thingiverse, as a case for including a drilled out and tapped M5 nut to secure a pulley on a motor shaft has already been published. Cannot happen to find that design right now.

* This method addresses concerns of sl