Worm Drive Gears Redux

This is AdditiveTech's excellent Worm Drive Gear, [Thing 2144347](http://www.thingiverse.com/thing:2144347), but with defects in the STL files corrected. (Usual flipped normals and other errors produced by software such as Sketchup. Wouldn't work correctly with a couple of common slicers.)

As per [Thing 2144347](http://www.thingiverse.com/thing:2144347), this is a 30:1 worm drive reduction gear in three parts. The worm wheel is helical.

https://youtu.be/VE7kmcveCOQ

Not that the crank/screw is best printed standing upright and with supports touching the build plate. Be careful removing the crank from the build plate; the orientation of the layers makes it easy to break it off leaving the base still attached to the build plate. Indeed, printing at a layer height of 0.2 mm may make for a tad sturdier part as opposed to a layer height of 0.3 mm.