When the follower movement is in a plane parallel to the cam shaft, an irregular cam must be employed.

Teeth are spaced by laying out equal angles.

The motion of the follower as it rises or falls depends on the shape of the curves in the displacement diagram.

A worm is a screw with a thread shaped like a rack tooth.

Working drawings for bevel gears give both the dimensions of the gear blank and the data necessary for cutting the teeth.