@glenn505 said: ......a project for me, but something I have been working on for years, and I think it's the biggest leap forward since the original Sturmey Archer AW4 hub, matching that hub in all areas, and bettering it in several. My design is less complicated than a Rohloff, equally efficient mechanically, and automatically shifting by torque, with no ancillary cables. Point is, I need at least some direction on drawing (still somewhat complicated) gears, interfacing in multiple planes, on multiple axis. So far I haven't even been able to get the gear plug-in (Ruby code) to work in Sketchup 8, so I'm rolling backward to 7, but still a little lost in this thing. Pointless asking you to share the sketches. No, I haven't done any serious modeling of gears in the past other than trying out what the native tools are capable of and how I would approach/tackle such a "problem". So I just downloaded gear.3.rb into sketchups plugin folder. You say it does not work for you? Unlike the info on the site, the options are presented in the 'Draw' menu. (So the tools are NOT in the 'Tools' menu). Both 'Involute Gear' and 'Key Involute Gear' do work for me.(in SU8pro!) I can only say (from what I see) that the teeth tops partly do 'share' the same 3D space when two wheels work togheter. Not as it should be. So you would still need to work on those teeth corners. You did not specify where you get stuck with specific SU problem(s).