And this gears: http://static.ddmcdn.com/gif/gear-worm.jpg

Thanks, I made it: http://www.youtube.com/watch?v=8T0TwphKSmY

Anybody, can advice me hot to make this gears: http://static.ddmcdn.com/gif/gear-bevel.jpg and http://static.ddmcdn.com/gif/gear-bevel2.jpg

I'm trying to make differential in Google SketchUp using this tutorial http://support.ponoko.com/entries/21249896-Gears-and-Joints-with-SketchUp-Sketchy-Physics for gears modeling. But I have problem: gears don't collide with any objects (and other gears). What's wrong? How to fix this?

How to make a bevel gear placed at 90 degrees relative to each other and conical cylindrical gears joints?

P.S. Is there something like SketchUp and SketchyPhisics in Linux?