UNCcoarse60° flankASME B1.1

#5-40 UNC Thread Dimensions

#5-40 UNC is a coarse Unified National Coarse thread. There are 40 threads per inch on a 0.1248 in major diameter, giving a metric-equivalent pitch of 0.635 mm. The recommended tap drill leaves roughly 75% thread engagement.

Major Ø0.1248 in
Threads per inch40
Pitch (metric)0.635 mm
Pitch Ø0.1087 in
Tap drill0.1 in

Thread profile

millimetres unless stated
Thread profile — #5-40 UNCd 3.17d2 2.76d3 2.4mm60°P 0.635h3 0.39tap ⌀2.54
#5-40 UNC — basic profile60° flank angle · Not to scale

Basic information

Designation
#5-40 UNC
Thread system
Unified National Coarse
Series
coarse
Standard
ASME B1.1
Basic profile
Unified basic profile
Flank angle
60°

Dimensions

Major diameter
0.1248 in / 3.17 mm
Pitch (metric equivalent)
0.635 mm
Threads per inch
40
Pitch diameter
0.1087 in / 2.76 mm
Minor diameter (external)
0.0945 in / 2.4 mm
Minor diameter (internal)
0.098 in / 2.49 mm
Thread depth
0.0154 in / 0.39 mm
Recommended tap drill
Ø 0.1 in / 2.54 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 #5-40 UNC yet.

Related

Neighbouring sizes in Unified National Coarse.

#1-64 UNC#2-56 UNC#3-48 UNC#4-40 UNC#6-32 UNC#8-32 UNC#10-24 UNC#12-24 UNC