1-1/4-5 ACME Thread Dimensions

Basic information

Designation

1-1/4-5 ACME

Thread system

ACME

Series

acme

Standard

ASME B1.5

Basic profile

ACME basic profile

Flank angle

29°

Dimensions

Major diameter

1.25 in / 31.75 mm

Pitch (metric equivalent)

5.08 mm

Threads per inch

5

Pitch diameter

1.15 in / 29.21 mm

Minor diameter (external)

1.0299 in / 26.16 mm

Minor diameter (internal)

1.0299 in / 26.16 mm

Thread depth

0.11 in / 2.794 mm

Recommended tap drill

Ø 1.05 in / 26.67 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 1-1/4-5 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.