The Dormer MTT-X E001/MTT-X E011 powdered-metal steel spiral point tap has a round shank with a square end, black oxide finish, and a plug chamfer, and is used to create metric right-hand threads in a number of materials, with best performance in steel. It is available in two different thread specification standards: Metric Coarse (M) or Metric Fine (MF). The spiral point of this tap (sometimes referred to as a “gun tap”) pushes chips ahead of the tool and the straight flutes reduce clogging. Both characteristics make it suitable for threading through holes (extending through the workpiece). The black oxide finish improves lubricity, resists corrosion, and will not chip or flake. It also helps to prevent buildup and welding of material on the tap’s cutting edge when working with iron and steel. The plug chamfer distributes cutting to ease tapping at the beginning of the hole and to maintain correct perpendicular alignment with the workpiece.
Right-hand threads are designed to tighten when a head or nut is rotated clockwise (the most common threading direction). Powdered-metal steel offers performance that approaches that of solid carbide tools but with the toughness and shock-resistance of high-speed steel. The round shank with square end helps to minimize rotation in the tool holder. This tool can be used in machines, such as drill presses or lathes, or with hand tools such as tap wrenches.
In the Dormer MTT-X E001 series, taps with nominal diameters of 3 mm to 16 mm have three flutes and taps with nominal diameters of 18 mm to 24 mm have four flutes. In the MTT-X E011 series, taps with nominal diameters of 4 mm to 16 mm have three flutes and taps with nominal diameters of 18 mm to 24 mm have four flutes. All taps in both series have plug chamfers. This tap conforms to ISO 529 standards and can create threads to a depth two-and-a-half times its diameter. It is suitable for the 6H tolerance class: 6H is used for a normal length of thread engagement and medium tolerance quality.
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.
Precision Dormer manufactures cutting tools under the following brands: Precision Twist, Dormer, and Union Butterfield. The company has locations around the world, and provides tools adhering to ANSI, NAS, and DIN standards.