Type 1 thread cutting screws have a machine screw pitch, blunt point, tapered lead in and a single cutting edge
Type 23 thread cutting screws have machine screw threads, a blunt point, tapered lead in, a single wide cutting edge and a chip cavity. Good for chip clearing and low tightening torques
Type 25 thread cutting screws have spaced threads, a blunt point, tapered lead in, a single wide cutting edge and a chip cavity. Good for molded plastic holes.
Type F thread cutting screws have a machine screw thread pitch, blunt point, tapered lead in, and multiple cutting edges. Good for heavy gauge sheet metal, aluminum, zinc and lead die castings, cast iron, brass and plastic. (Sometimes Called Floorboard Screws)
