We’ve all had this happen at some point while tightening hardware: It feels like it’s snugging up nicely, and then it suddenly seems to tun too easily. Or maybe you were removing stubborn hardware and ...

We have all done it, overtightened a bolt and blown out the threads. When a bolt starts to tighten up and then go suddenly loose, you know that the threads are toast and now you have a problem.

Inserts are classified as two general types: those held in place by external threads and those that use some means other than threads (knurls, grooves, interference fit) for their holding power.