Diameter: #12 Length: 3/4 Material: Steel Finish: Zinc Head Style: Flat Undercut (Phillips) Thread Size: 24 (Coarse) Thread Length: Full Type: Machine Screw A machine screw also called a stove bolt is generally a smaller fastener threaded the entire length of its shank. Machine screws are used in fastening nearly all types of hard materials. Especially useful in metal-to-metal or where heavy duty fastening is required. Commonly used with flat or lockwashers.