This product is a 9/16" UNC right‑hand split die designed for cutting and restoring Unified National Coarse (UNC) threads on shafts, studs and bolts. The die provides a convenient, adjustable thread‑cutting solution: the split design allows a small amount of radial adjustment so you can tighten or loosen the fit to suit repair or new‑cut threads, and it is intended for use with a compatible die stock.

The die is manufactured from high speed steel (HSS), typically M2 grade, which gives the cutting edges good hot hardness and wear resistance compared with carbon tool steels. The cutting faces are ground to the UNC profile to meet the Unified thread form and supplied with a dark oxide finish that offers modest corrosion protection and reduces glare when machining. The thread form is UNC (Unified National Coarse) to ANSI/ASME B1.1; it will match UN coarse fasteners and is compatible in assemblies that specify UNC thread form under BS/ISO/ANSI common practice. The item is a right‑hand (RH) die in the nominal 9/16" size; the die body is produced in a 1 5/16" body form to fit standard die stocks with the corresponding across‑flats size.

These HSS split dies are used widely in maintenance, engineering and fabrication environments where on‑site thread repair or one‑off production of UNC threads is required. Typical industries include automotive and vehicle repair, industrial plant maintenance, oil and gas, agricultural machinery and general mechanical engineering. The HSS material and ground cutting form make it suitable for cutting in mild and alloy steels, free‑cutting stainless steels (with suitable lubricant), and non‑ferrous materials, though lubrication and correct cutting speed are important for stainless applications.

Key benefits include the ability to adjust thread fit via the split clamp screw, long tool life from M2 HSS, and direct compatibility with existing UNC fasteners and standard die stocks. The black oxide finish helps resist corrosion in workshop environments while the ground profile ensures consistent thread geometry. Duchy Fasteners stocks these split dies in common imperial sizes, supplied individually and in boxed packs for trade and workshop use; contact us for available sizes and pack quantities.