NPT NATIONAL PIPE TAPER BUTTON DIES

NPT NATIONAL PIPE TAPER BUTTON DIESSutton Tools National Pipe Taper (NPT) Button Dies are premium quality threading tools engineered for cutting new external threads or chasing worn threads on imperial pipes and pipe fittings. Sutton manufactures these dies in a universal 2 inch Outside Diameter (OD), making them compatible with standard 2" adjustable die stock handles or guides. Geometric & Dimensional Breakdown OF 1 8 x 27TPI Thread Size: 1 8" NPT (National Pipe Taper). The "1 8

Sutton Tools National Pipe Taper (NPT) Button Dies are premium-quality threading tools engineered for cutting new external threads or chasing worn threads on imperial pipes and pipe fittings. Sutton manufactures these dies in a universal 2-inch Outside Diameter (OD), making them compatible with standard 2" adjustable die stock handles or guides.

• Thread Size: 1/8" NPT (National Pipe Taper). The "1/8 inch" designation refers to the nominal inside diameter of the pipe it threads, not the physical size of the die or the external pipe diameter.
• Pitch (TPI): 27 Threads Per Inch.
• Outside Diameter (OD): 2 inches (50.8 mm). This is a massive outer disc size relative to the tiny 1/8" cutting hole, requiring a standard 2" die stock handle.
• Thickness: Approx. 5/8 inch (15.8 mm), providing enough depth to handle the standard length of an NPT pipe engagement.
• Thread Taper: 1:16 taper ratio (0.75 inches per foot or ≈ 1.79° angle relative to the center axis). This taper ensures that as the male fitting is screwed into a female port, the threads wedge tightly together to create a seal.

• Composition: Made from high-carbon tool steel with a bright finish.
• Best Suited For: Thread cleaning (chasing), rust removal, and cutting new threads into soft materials like plastics, brass, copper, and aluminium. 
• Critical Limitation: Carbon steel lacks the red-hardness of High-Speed Steel (HSS). It should not be used to cut new threads on stainless steel or high-tensile carbon steel pipes, as it will dull or chip the teeth quickly.
• Application Warning: Per Sutton Tools' product documentation, carbon alloy dies are rated for general purpose / DIY use only and are not suitable for critical pressure, safety, or precision industrial pipework.

• Target Major Diameter (Pipe Outer Edge): The pipe end must have a starting outside diameter of roughly 0.405 inches (10.29 mm).
• Chamfer Requirement: Give the tip of the pipe a 30° to 45° bevel (chamfer) down to about 9.3 mm. Because NPT dies cut on a taper, they require a heavily beveled leading edge to help the first 27-TPI teeth bite into the material square.
• Hand Tapping Rotation: Turn the die 1/2 turn forward, then 1/4 turn backward to fracture and clear out metal chips from the internal waste flutes. Always use a dedicated thread cutting fluid (or soapy water for plastics) to protect the carbon edges.