3/8-12 ACME Thread Dimensions

Basic information

Designation

3/8-12 ACME

Thread system

ACME

Series

acme

Standard

ASME B1.5

Basic profile

ACME basic profile

Flank angle

29°

Dimensions

Major diameter

0.375 in / 9.525 mm

Pitch (metric equivalent)

2.117 mm

Threads per inch

12

Pitch diameter

0.3335 in / 8.47 mm

Minor diameter (external)

0.2717 in / 6.9 mm

Minor diameter (internal)

0.2717 in / 6.9 mm

Thread depth

0.0517 in / 1.312 mm

Recommended tap drill

Ø 0.2917 in / 7.408 mm

These figures follow the ACME basic profile of ASME B1.5. A 29° ACME profile has a thread height of h = 0.5 × P + 0.01 in, the 0.01 in being the ACME clearance rather than a rounding: the pitch diameter is d₂ = d − 0.5 × P, the external minor diameter is d₃ = d − 2h, and the internal minor diameter is D₁ = d − P − 0.02 in. The recommended tap drill is given as nominal diameter minus pitch, which here sits 0.02 in above the basic internal minor diameter — that 0.02 in is the ACME crest clearance — so it is a starting point rather than a cutting recommendation.

No specification in this database uses 3/8-12 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.