First, let me apolgize in advance for any feelings of inadequacy that may stifle your own woodworking projects after watching these videos. Don't sweat it.
Your day job probably isn't in the engineering, mechanics, manufacturing, robotics or design industry, and thus you probably don't have deep expertise in CAD/CAM technology. Or designing robots and other large, articulated, multi-functional equipment out of wooden gears and cams. You probably don't have the flexible schedule of a self-employed at-home-dad, either. Or a sprawling, high-tech workshop full of the latest tools and gadgets.
But then, it turns out, neither does this guy in Yamanashi, Japan. He works a completely unrelated day job, and builds these insane wooden gear-driven robots and diggers and what nots on nights and weekends, in his driveway, under a tarp, with and for his kids. And he does it using graph paper, trial & error, and some tutorials he found online. Hmm, perhaps you shouldn't have read this last parapgraph.
Ki no Haguruma (wooden gear car)'s YouTube channel [youtube via dt reader cam]
Ki no Haguruma Kojo (factory) homepage [geocities.jp (!)]
Previously, related: Stunning wood toys by Take-G