Counterbore drills are dedicated cutting tools for drilling counterbore holes by attaching to a milling machine or drill press. The countersinking cutting tool that sinks the bolt head is also called a sinking milling machine, and has an induction pilot section that makes the pilot hole and the countersink hole concentric. There are blade shapes that can be used for bolt through holes and counterboring at the same time, those that are suitable for countersunk screws, and those that are suitable for hex socket head bolts. There are also punches and extrusion pins suitable for mold processing. As the tool base material, metals that can withstand cutting, such as high-speed steel and cemented carbide, are often used, and some products have been subjected to coating to increase durability. When selecting a countersunk product, it is necessary to check the size of the tip, the shape and size of the countersink hole that can be processed, etc. in advance