UNCcoarse60° flankASME B1.1

#3-48 UNC Thread Dimensions

#3-48 UNC is a coarse Unified National Coarse thread. There are 48 threads per inch on a 0.0988 in major diameter, giving a metric-equivalent pitch of 0.529 mm. The recommended tap drill leaves roughly 75% thread engagement.

Major Ø0.0988 in

Threads per inch48

Pitch (metric)0.529 mm

Pitch Ø0.0854 in

Tap drill0.0783 in

Thread profile

millimetres unless stated

#3-48 UNC — basic profile60° flank angle · Not to scale

Basic information

Designation: #3-48 UNC
Thread system: Unified National Coarse
Series: coarse
Standard: ASME B1.1
Basic profile: Unified basic profile
Flank angle: 60°

Dimensions

Major diameter: 0.0988 in / 2.51 mm
Pitch (metric equivalent): 0.529 mm
Threads per inch: 48
Pitch diameter: 0.0854 in / 2.17 mm
Minor diameter (external): 0.0736 in / 1.87 mm
Minor diameter (internal): 0.0764 in / 1.94 mm
Thread depth: 0.0128 in / 0.325 mm
Recommended tap drill: Ø 0.0783 in / 1.99 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 #3-48 UNC yet.

Neighbouring sizes in Unified National Coarse.

#1-64 UNC #2-56 UNC #4-40 UNC #5-40 UNC #6-32 UNC #8-32 UNC