UNCcoarse60° flank

9/16-12 UNC Thread Dimensions

9/16-12 UNC is a coarse pitch UNC thread. There are 12 threads per inch, giving a pitch of 2.12 mm. The recommended tap drill leaves roughly 75% thread engagement.

Nominal Ø14.29 mm
Pitch2.12 mm
Threads per inch12
Pitch Ø-20.63 mm
Tap drill-39.48 mm

Thread profile

millimetres unless stated
Thread profile — 9/16-12 UNCd 14.29d2 -20.63d3 -51.67mm60°P 2.12h3 32.98tap ⌀-39.48
9/16-12 UNC — basic profile60° flank angle · Not to scale
Designation
9/16-12 UNC
Thread system
UNC
Series
coarse
Flank angle
60°
Major diameter
14.29 mm / 0.56"
Pitch
2.12 mm
Threads per inch
12
Pitch diameter
-20.63 mm
Minor diameter (external)
-51.67 mm
Minor diameter (internal)
-43.91 mm
Thread depth
32.98 mm
Recommended tap drill
Ø -39.48 mm / -1.5542"

How these values are derived

Basic ISO thread geometry uses the fundamental triangle height H = 0.866025 × P. External minor diameter d₃ = d − 1.226869 × P, internal minor diameter D₁ = d − 1.082532 × P. Tap drill is given as nominal diameter minus pitch, which approximates a 75% thread engagement — adjust for tough materials or deep holes.