13 Piece High Speed Steel Screw Machine (Stub Length) Drill Bit Set. Sizes 1/16" - 1/4" x 64ths (1/16", 5/64", 3/32", 7/64", 1/8", 9/64", 5/32", 11/64", 3/16", 13/64", 7/32", 15/64" and 1/4"). Screw machine drills (also know as stub or stubby drills) are manufactured to National Aerospace Standard 907. The 135 degree 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. Screw machine drills are popular in the automotive and construction industries. They are often used in screw machine setup where spindle clearance is limited. Sizes smaller than 1/16 and #52 have the 118 degree standard point.