UNCcoarse60° flankASME B1.1

#1-64 UNC Thread Dimensions

#1-64 UNC is a Unified National Coarse thread. There are 64 threads per inch on a 0.073 in major diameter, giving a metric-equivalent pitch of 0.397 mm. The recommended tap drill is nominal diameter minus pitch.

Major Ø0.073 in
Threads per inch64
Pitch (metric)0.397 mm
Pitch Ø0.063 in
Tap drill0.0574 in

Thread profile

millimetres unless stated
Thread profile — #1-64 UNCd 1.854d2 1.6d3 1.37mm60°P 0.397h3 0.243tap ⌀1.457
#1-64 UNC — basic profile60° flank angle · Not to scale

Basic information

Designation
#1-64 UNC
Thread system
Unified National Coarse
Series
coarse
Standard
ASME B1.1
Basic profile
Unified basic profile
Flank angle
60°

Dimensions

Major diameter
0.073 in / 1.854 mm
Pitch (metric equivalent)
0.397 mm
Threads per inch
64
Pitch diameter
0.063 in / 1.6 mm
Minor diameter (external)
0.0539 in / 1.37 mm
Minor diameter (internal)
0.0559 in / 1.42 mm
Thread depth
0.0096 in / 0.243 mm
Recommended tap drill
Ø 0.0574 in / 1.457 mm

How these values are derived

computed from the basic profile

These figures follow the Unified basic profile of ASME B1.1. A 60° basic profile has a fundamental triangle height H = 0.866025 × P, with pitch diameter d₂ = d − 0.649519 × P, external minor diameter d₃ = d − 1.226869 × P and internal minor diameter D₁ = d − 1.082532 × P; the two minor diameters differ because the external root is rounded while the internal crest is truncated. The recommended tap drill is given as nominal diameter minus pitch, which approximates 75% thread engagement — adjust it for tough materials or deep holes.

Compatible parts0 specification pages

No specification in this database uses #1-64 UNC yet.

Related

Neighbouring sizes in Unified National Coarse.

#2-56 UNC#3-48 UNC#4-40 UNC#5-40 UNC