M5.5 × 0.9 Thread Dimensions

Basic information

Designation

M5.5 x 0.9

Thread system

ISO Metric

Series

coarse

Standard

ISO 261

Basic profile

ISO 68-1 basic profile

Flank angle

60°

Dimensions

Major diameter

5.5 mm

Pitch

0.9 mm

Threads per inch

28.22

Pitch diameter

4.92 mm

Minor diameter (external)

4.4 mm

Minor diameter (internal)

4.53 mm

Thread depth

0.552 mm

Recommended tap drill

Ø 4.6 mm

These figures follow the ISO 68-1 basic profile of ISO 261. 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 M5.5 × 0.9 yet.

Neighbouring sizes in ISO Metric.