This is AdditiveTech's excellent Worm Drive Gear, 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, this is a 30:1 worm drive reduction gear in three parts. The worm wheel is helical.
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.
Print the crank standing upright with support material touching the build plate. The base and spur wheel do not require support.