Tool to tap an inner thread within a deep core hole, in a workpiece, has a tap shaft extension inserted into the hole in front of the cutting head to give a self-centering action

摘要

The tap (1) to cut an inner thread within a deep core hole (7) in a workpiece (12) has an extension (4) to the tap shaft which is inserted into the guide section (9) of the hole. The extension has a diameter matching the hole dimensions so that it can only move in and out. with the thread cutting action of the cutting head (3).