Drill America - D/Ast7P12 #7 High Speed Steel Heavy Duty Split, D/Ast Series Drill America D/AST series High-Speed Steel screw machine length drill bit. Manufactured to National Aerospace Standard 907. 135 degrees split point is self-centering and reduces thrust. Ideal for portable or machine drilling. Short, rugged construction performs well in a broad range of materials in the iron and steel families. Screw machine drills are popular in the automotive and construction industries. It is often used in screw machine setup where spindle clearance is limited. High-speed steel tools are good for most general purpose applications, offering a combination of hardness and toughness for wear resistance Black oxide treatment adds lubricity and creates small pockets on the surface of the tool that act to hold coolant near the cutting edge Round shanks allow use with a wide variety of toolholding systems When run in a counterclockwise direction (right-hand cut) spiral fluted tools evacuate chips up and out of the cut to reduce clogging Ideal for portable or machine drilling