The Union Butterfield 1500A(UNC)/1500A(UNF) high-speed steel hand threading tap has straight flutes, a round shank with a square end, and a black oxide surface finish, and is used to create right-hand threads in a range of materials. It is available in two different ANSI thread specification standards: UNC (Unified Coarse) or UNF (Unified Fine). The straight flutes are suitable for threading through holes (extending through the workpiece) and blind or bottoming holes (with only one opening). The black oxide finish of this tool will not chip, improves lubricity, resists corrosion, and helps to prevent buildup and welding on the cutting edge of the tool.
Right-hand threads are designed to tighten when the head or nut is rotated clockwise (the most common threading direction). High-speed steel (HSS) is a common general-purpose steel for cutting tools and is compatible with a variety of materials. The round shank with square end makes this tap suitable for hand or power-driven applications. This tool can be used in machines, such as drill presses or lathes, or with hand tools such as tap wrenches.
In the Union Butterfield 1500A(UNC) and 1500A(UNF) series, all taps have four flutes. They are available with a variety of chamfers. This tap conforms to ANSI standards and can create threads to a depth 1 ½ times its diameter. It is suitable for the ANSI 3B tolerance class: 3B produces close-tolerance fasteners that resist loosening, as in aerospace applications.
Taps produce internal threads in previously formed holes and can be used in machines (such as drill presses) or with hand tools. Common types of taps include hand taps, spiral point taps, spiral flute taps, thread forming taps, and pipe taps. Hand taps (straight-flute taps) collect chips in the straight flutes of the tool; spiral point taps push chips through holes ahead of the tool; and spiral flute taps pull chips back from the tip of the tool, up and out the hole. Thread forming taps, also known as cold forming taps, press rather than cut to create threads in a drilled hole, and no chips are created. Pipe taps create threads in pipes and pipe fittings. Each thread type designates a thread profile and each type is identified with an abbreviation. In the U.S. and Canada, the Unified Thread Standard is the dominant thread type, including UNC (Unified Coarse), UNF (Unified Fine), and NPT (National Pipe Taper) threads, among others.