When a bolt breaks, it's usually right below the wrenching head (the head "pops off"), or in a blind-thread application, at the shank-to-first thread lead in. Wrenching-head failures are usually ...

The bolt shank could break, or the threads may strip, providing no clamping force at all. The best way to tighten fasteners is with a device called a torque wrench. Why don't we simply tighten ...

and the last thread has a fillet radius that transitions to the shank of the bolt. Because the bolt needs to stretch equally, this diameter is maintained until just below the head of the bolt.

Few things seem more hopeless than when you’re in the process of removing a bolt, screw, or stud and it breaks. At that point, you know it’s all over but the crying. You’ve busted a bolt off ...

This could cause you to break a blind stud, which could mean hours of drilling out the busted shank ... the bolt actually rusted or does it have locking compound? Many factory bolts have thread ...

Or calculate it based on the equation from ASME Standard B1.1-1989 (revision of ANSI B1.1-1982) for unified inch screw threads ... of the shank, Ls, includes one-third of the bolt-head height.