MakerGear M2 Z Axis Knob - Spiral

This is inspired by [Mrclean6](http://www.thingiverse.com/Mrcleanr6/designs)'s [makergear m2 z axis knob](http://www.thingiverse.com/thing:471905).

I used a long set screw (from my local ACE) in the original M2 knob's steel lock collar, the length of the set screw keeps the steel lock collar from moving inside the knob. You can just see the set screw's head in the lower left of the photo.

I used some very elegant (or inelegant, it might be argued) Open SCAD for loops to make the spirals. T