AddendaTips of the teeth of a wheel beyond the pitch circle.
We may also say that the pitch circle is the edge of the pitch surface.
By the diameter of a wheel is meant the diameter of its pitch circle.
And to pencil in the teeth these circles must be fully drawn, as in Figure 234, in which P P is the pitch circle.
Where these divisions intersect the pitch circle are the centres from which all the teeth curves may be drawn.
The circumference of the pitch circle divided by the arc pitch gives the number of teeth in the wheel.
The arc pitch multiplied by the number of teeth in the wheel gives the circumference of the pitch circle.
The depth below pitch line or the length of flank is, therefore, the distance between the pitch circle and the base circle.
The amount of error thus induced diminishes as the diameter of the pitch circle of the cutter is increased.
The flank of each wheel is struck with a tracing point, thus attached to the pitch circle of the other wheel.