The cog macros were developed for use in the bicycle then extended.
There are two main sets of cog macros; one for use with chains where the teeth are thinner than the spaces between them and one for meshing cogs where the teeth and the spaces between are equal. These are both constructed is also a more general cog macro which can alter the tooth size and spacing any way
The chain macros are designed to have round spaces between the teeth so that a cylinder from a chain would fit nicely in between them. At the moment the chains themselves do not have links which can fit the cog teeth but are solid. The two types of chain, round and rectangular, are constructed using the formula for sphcone to seamlessly join the circles formed by the two cogs. The chain macros use the ring macros from wheels to generate the round portion of the chain.
The meshing cogs have spacing equal to the width of the teeth. This is so that when placed next to each other a tooth from one cog will fit nicely into the space between two teeth from the other cog.
bike