Regular visitor Tom Beutel sent in these pictures of his mechanism design. He plans to use the model as the starting point for other designs. Train, twirling ballerina, that sort of thing. The larger gear has 16 teeth, the smaller one eight, giving a ratio of 2:1. Two turns of the handle to one turn of the vertical shaft. Tom says that it runs nice and smoothly. I'm looking forward to seeing how he uses the mechanism in future models – nice work Tom!