scope:

General

The buttress form of thread has certain advantages in applications involving exceptionally high stresses in one direction only, along the thread axis. As the thrust side of the thread is made very nearly perpendicular to the thread axis, the radial component of the thrust is reduced to a minimum. On account of the small radial thrust, this form of thread is particularly applicable where tubular members are screwed together. Examples of actual applications are the breech mechanisms of large guns and airplane propeller hubs.

As the use of buttress threads applies mainly to specially designed components, it has been considered that no useful purpose would be served by introducing a recommended diameter- pitch series.

In selecting the form of thread recommended as standard, manufacture by the thread milling or grinding processes has been taken into consideration. Wherever possible it is recommended that the form of thread and tolerances contained in this standard be used