1. Measuring & Marking Out Produced by Neil Liggett
Pitch Circle Diameter

2. Pitch Circle Diameter
When features are equally spaced on a circle, the circle is called a pitch circle diameter (PCD), i.e. Bolt holes positioned equally about an axle or alloy wheels.

3. Pitch Circle Diameter
When measuring and marking out PCD’s, pitch values can be converted to chord lengths, these values can be obtained from manuals and engineering text books.

4. Pitch Circle Diameter
Multiply pitch values by the diameter to calculate the chord lengths.
To find chord length for marking 7 holes equally spaced on a 125 mm PCD
X 125 = mm