1/4-16 ACME Thread Dimensions

Basic information

Designation

1/4-16 ACME

Thread system

ACME

Series

acme

Standard

ASME B1.5

Basic profile

ACME basic profile

Flank angle

29°

Dimensions

Major diameter

0.25 in / 6.35 mm

Pitch (metric equivalent)

1.587 mm

Threads per inch

16

Pitch diameter

0.2189 in / 5.56 mm

Minor diameter (external)

0.1673 in / 4.25 mm

Minor diameter (internal)

0.1673 in / 4.25 mm

Thread depth

0.0413 in / 1.048 mm

Recommended tap drill

Ø 0.1874 in / 4.76 mm

These figures follow the ACME basic profile of ASME B1.5. 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.

No specification in this database uses 1/4-16 ACME. Power threads are not fastener threads — they are found on lead screws, jacks and vice screws, so no bolt or nut in this catalogue is made in this form. The geometry above is what a machinist needs to cut it.

Neighbouring sizes in ACME.