AS8879E Screw Threads - UNJ Profile, Inch, Controlled Radius Root with Increased Minor Diameter
Revised
9/25/2026
- Content
- This SAE Aerospace Standard (AS) specifies the characteristics of screw threads - UNJ profile, inch, series, including a mandatory controlled radius as specified in Table 1 at the root of the external thread. The minor diameter of both external and internal threads provides a basic thread height of .5625H to accommodate the external thread maximum root radius. The following detailed design requirements are included:
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Screw threads - UNJ basic profile and design profiles.
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Standard series of diameter-pitch combinations for nominal thread diameters from 0.060 to 6.000 inches.
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Standard thread classes and form tolerances.
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Formulae for thread dimensions and tolerances.
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Method of designating UNJ threads.
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Tables for selected diameter-pitch combinations for close tolerance mechanical thread applications.
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Tables for screw thread - UNJ profile thread limit dimensions.
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- Citation
- SAE International Technical Standard, Screw Threads - UNJ Profile, Inch, Controlled Radius Root with Increased Minor Diameter, SAE Standard AS8879E, Revised September 2026, Reaffirmed April 2024, Issued January 1999, https://doi.org/10.4271/AS8879E.