Extruder Cooling, Printrbot Simple V2

**The filament guide on this will not work on Simples ordered after October 2013. Printrbot modified this area to eliminate the removable filament guide and closed up the opening used for this filament guide/fan mount combo. The other fan mounts should still work without issue.**

Having difficulty with heat above the hot end so I designed some heat dissipation components.

1. Extruder gear - I incorporated a fan mount into my filament guide. This allows quick removal and access to the ex