This SAE Aerospace Standard (MA) provides recommended dimensional data for screw thread undercuts for straight “MJ” metric screw threads in accordance with MA1370.Purpose:

Application:

The thread undercut data included in this document are primarily designed to provide a clearance for threading tool runout either where the thread is in a blind hole or where the thread is close to an adjacent shoulder. These thread undercuts are not recommended for bolts, screws, or studs which are required to be necked; e.g., reduced shank contiguous to the thread, to improve their tensile, impact, and cyclic load performance.