Jet Engine Model Motor Drive

This is a motor drive for the GE "Build Your Own Jet Engine". It replaces the hand crank of the original.
I designed this to use a motor, switch and battery holder available from any RadioShack store.
The gearbox is a 243:1 speed reduction based on the design from "mirk", but shrunk to 50%. The drive chain and drive gears are based on the design by "peanut", only shrunk in width. I also had to re-draw both of these as Slic3r was messing up on the edited versions I originally tried.
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