Thread Measuring Wires per ASME B89.1.17
PITCH DIAMETER = MEASUREMENT OVER WIRES (MOW) – CONSTANT
W = Wire Size
P =Pitch = 1 / # of Threads per Inch = The distance the thread travels in one turn.
C = Constant = 3w - .86602540P
PD = Pitch Diameter = the halfway point between sharp major & minor diameters.
Measured PD = MOW - (3w - 0.88602540P)
Applicable ANSI / ASME Standards:
B89.1.17 “Measurement of Thread Measuring Wires”
B1.7M “Nomenclature, Definitions, & Letter Symbols for Screw Threads”
B1.1 “Unified Inch Screw Threads (UN & UNR Thread Form) ”
B1.2 “Gages & Gaging for Unified Inch Screw Threads”
B1.13M “Metric Screw Threads: M Profile”
B1.16M “Gages & Gaging for Metric M Screw Threads”