Bolt tap, how to fix a thread without a tool

Surely many often faced with the need to "drive" the thread, without having the right tap. A bolt with the same thread always comes to the rescue, but cleaning and straightening the thread with it is not always convenient. So that the turns on the makeshift tap are not clogged with rust, you can make two or three grooves at the very beginning of the threaded part.

This is an easy and quick way to help make a tool that comes in handy more than once.