This Grasshopper file allows you to make gears in Rhino with varying geometry - inner/outer diameter, # spokes, # teeth, etc. All of the gear's parameters are controlled by numerical sliders. Dr. Henry Casson, who is interested in clock mechanisms, helped me with the design of this file. Note that the ends of the gear teeth are circular arcs. Ideally these curves should be involutes, but I have not yet found a way to make such curves. Although the overall design of this file is for clock gears it could easily be used and/or adapted for other purposes.