UNFfine60° flankASME B1.1

#2-64 UNF Thread Dimensions

#2-64 UNF is a fine Unified National Fine thread. There are 64 threads per inch on a 0.0858 in major diameter, giving a metric-equivalent pitch of 0.397 mm. The recommended tap drill leaves roughly 75% thread engagement.

Major Ø0.0858 in
Threads per inch64
Pitch (metric)0.397 mm
Pitch Ø0.076 in
Tap drill0.0705 in

Thread profile

millimetres unless stated
Thread profile — #2-64 UNFd 2.18d2 1.93d3 1.7mm60°P 0.397h3 0.243tap ⌀1.79
#2-64 UNF — basic profile60° flank angle · Not to scale

Basic information

Designation
#2-64 UNF
Thread system
Unified National Fine
Series
fine
Standard
ASME B1.1
Basic profile
Unified basic profile
Flank angle
60°

Dimensions

Major diameter
0.0858 in / 2.18 mm
Pitch (metric equivalent)
0.397 mm
Threads per inch
64
Pitch diameter
0.076 in / 1.93 mm
Minor diameter (external)
0.0669 in / 1.7 mm
Minor diameter (internal)
0.0689 in / 1.75 mm
Thread depth
0.0096 in / 0.243 mm
Recommended tap drill
Ø 0.0705 in / 1.79 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 uses a fundamental triangle height H = 0.866025 × P, with external minor diameter d₃ = d − 1.226869 × P and internal minor diameter D₁ = d − 1.082532 × P; the two differ because the external root is rounded while the internal crest is truncated. A 55° Whitworth profile uses H = 0.960491 × P and a thread height of 0.640327 × P. 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 #2-64 UNF yet.

Related

Neighbouring sizes in Unified National Fine.

#0-80 UNF#1-72 UNF#3-56 UNF#4-48 UNF#5-44 UNF#6-40 UNF