UNCcoarse60° flankASME B1.1

#2-56 UNC Thread Dimensions

#2-56 UNC is a Unified National Coarse thread. There are 56 threads per inch on a 0.086 in major diameter, giving a metric-equivalent pitch of 0.454 mm. The recommended tap drill is nominal diameter minus pitch.

Major Ø0.086 in
Threads per inch56
Pitch (metric)0.454 mm
Pitch Ø0.0744 in
Tap drill0.0681 in

Thread profile

millimetres unless stated
Thread profile — #2-56 UNCd 2.184d2 1.89d3 1.63mm60°P 0.454h3 0.278tap ⌀1.731
#2-56 UNC — basic profile60° flank angle · Not to scale

Basic information

Designation
#2-56 UNC
Thread system
Unified National Coarse
Series
coarse
Standard
ASME B1.1
Basic profile
Unified basic profile
Flank angle
60°

Dimensions

Major diameter
0.086 in / 2.184 mm
Pitch (metric equivalent)
0.454 mm
Threads per inch
56
Pitch diameter
0.0744 in / 1.89 mm
Minor diameter (external)
0.0642 in / 1.63 mm
Minor diameter (internal)
0.0665 in / 1.69 mm
Thread depth
0.0109 in / 0.278 mm
Recommended tap drill
Ø 0.0681 in / 1.731 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 #2-56 UNC yet.

Related

Neighbouring sizes in Unified National Coarse.

#1-64 UNC#3-48 UNC#4-40 UNC#5-40 UNC#6-32 UNC