A 5 mm x 0.8 HSS dienut is a split round die designed to cut or restore external M5 metric threads with a 0.8 mm pitch on bolts, studs, rods and turned components. It is intended for use in a standard die stock (hand-held die holder) or low-speed machine die holder and is suitable for both new thread cutting and repair of damaged or worn threads.

The die is manufactured from high-speed steel (HSS), typically M2 grade, and is ground to provide accurate cutting edges. The thread produced conforms to the ISO metric thread form (60° profile) and is compatible with the tolerances and thread series defined by ISO 261/965 and BS 3643; it will also suit common DIN metric thread forms used in UK engineering practice. The product is a split (adjustable) round die with an adjustment screw that allows slight size tuning for achieving the required fit and for compensating wear. It is finished with a precision ground face; some items incorporate a light black-oxide passivation to reduce surface corrosion and aid chip release.

Typical applications include maintenance and repair work in mechanical workshops, small-batch engineering, electrical enclosure assembly, instrumentation and model-making where M5 external threads are common. It is frequently used by automotive technicians, maintenance engineers and hobbyists to cut threads on studding, turned shafts and repair stripped fasteners. The HSS material delivers good red-hardness and wear resistance compared with carbon-steel dies, making it better suited to intermittent production and tougher materials such as free-cutting steels and some stainless steels when used with appropriate cutting lubricant and conservative feed rates.

Key benefits are long cutting life from M2 HSS, accurate ISO-compatible thread form, and the adjustability of the split die which allows a close tolerance fit or light tightening for repair tasks. Compatibility with standard die stocks and the common M5 × 0.8 thread size makes this dienut a practical choice for general workshop use.

Duchy Fasteners stocks a broad range of HSS die nuts across metric sizes and supplies them singly or in small packs to suit trade and DIY requirements; please contact us for available sizes and pack quantities.