How do you repair a thread with an insert?

Repair a stripped thread with an insert by using the drill block to keep the bit straight, and drill an oversized bolt hole, using the tap to cut threads that accommodate the outside of the insert and screwing it into place. The inside of the insert provides the new threads.

Inserts are useful when the threads of a bolt hole in a machine are damaged, such as with an automobile engine. The insert restores the hole and threads to the original size. Because the insert provides steel-to-steel contact for the bolt, the new connection is actually stronger than most bolt holes that are steel to cast iron.