To measure or determine the unknown distance c over adjacent hole or pins (largest gage pins that can fit into holes) within a bolt circle of holes (n or number of bolts holes must be even and greater than 4), as shown left in Illustration B, use the equation:
c = the distance over adjacent pins
d = the diameter of the holes
θ = 360°/n or angle between adjacent holes.
All units shall be consistant and given in inches or mm. Angles (theta) are given in degrees