Printrbot Simple beta Z-axis Knob

A simple knob for the top of the 5/16" all-thread on the Printrbot Simple beta. Since the printer doesn't have endstops, it's nice to be able to make fine adjustments to the printhead height.

Please note that as with many of the things designed for the original Printrbot Simple beta, this knob is **not usable** with the current production Simple, which now comes with Acme rod; instead, try http://www.thingiverse.com/thing:145804