Thread extractor
A thread extractor is a tool for removing broken screws or threaded pins that no longer protrude from the threaded hole . Since no part of the screw or the pin is available to “touch” and unscrew it, a central hole is drilled into it to accommodate a thread extractor. The thread extractor has a left-hand thread on a conical shaft for use with screws with right-hand threads. When turned to the left, it turns into the drilled hole and wedges itself in it. If you continue turning, such a broken screw or pin is unscrewed from the threaded hole.