On the web there is a rather classy looking site that will design involute gears for you, and output DXF or SVG CAD files so that you can make them. And it looks like it came about through the ...

Some spare time recently got used-up designing a pair of involute gears – which, it transpires, is easy in principle, once certain almost-impossible-to-obtain facts have been gathered. There are ...

, 'involute gears' and 'cycloid gears', based on the difference in tooth shape. Both types have their own advantages, but technology blogger lcamtuf explains the advantages of involute gears. A ...