SAE MA1370

Description / Abstract: This standard specifies the characteristics of the MJ profile metric series of screw threads, altered from ISO 68 M Profile, to include a mandatory controlled radius of 0.18042P to 0.15011P at the root of the external thread and with the minor diameter of both external and internal threads increased to provide a basic thread height of 0.5625H in order to accommodate the external thread maximum root radius. The following detailed requirements are included:

a. MJ basic profile and design profiles

b. Standard series of diameter-pitch combinations for nominal thread diameters form 1.6 to 200 mm

c. Standard thread classes and form tolerances

d. Formulae for thread dimensions and tolerances

e. Method of designating MJ threads f. Inspection requirement

g. Tables for selected diameter-pitch combinations for aerospace screws, bolts, nuts, shaft and bearing retaining screw threads, and fluid fittings thread sizes

h. Tables for MJ screw threads limiting dimensions and tolerances

i. Symbols for MJ thread dimensions and tolerances

Purpose:

To establish a metric module version of the UNJ profile, MIL-S-8879 inch screw thread standard, predominantly used in aerospace inch designs.