Drill tap is a combination of drill and tap to drill, tap and chamfer a through hole in one quick step. You can create many common screw holes for machine screws and bolts by inserting the drill tap into impact driver without switching cutting tools which really saves lots of time and money.
Step drills are drill bits easy to cut and enlarge a wide range of holes on thin sheet metal, plastic and other materials at a lower speed. Due to the stepped design of multiple diameters, you can drill different-sized holes by one or two step drills. Use an appropriate step drill in a right way can help you make good works.