This is a 4 mm × 0.7 HSS die nut for cutting or repairing external metric threads on round bar, studs and bolts. It is intended for use with a compatible die stock or machine holder to produce standard M4 × 0.7 (metric) right‑hand external threads on mild steel, aluminium, brass and other machinable materials. Its primary use is forming or restoring threads where a small, precise external thread is required.

The die nut is manufactured from high speed steel (HSS), typically M2 grade, and supplied with a bright ground finish to give a true cutting profile and long tool life. The thread form produced conforms to the ISO metric profile (M4 × 0.7) in accordance with ISO 724 (equivalent to DIN 13 for metric thread dimensions). When used with suitable setup and lubrication the die nut can achieve standard external thread tolerances consistent with ISO 965/1 (tolerance class 6g for external threads).

This style of die nut is compatible with standard hand die stocks and machine holders. It is a through‑type die nut (no head or drive required) and is located and tightened in a die stock using the conventional securing screws. The split/adjustable design commonly used for similar dies allows slight size adjustment and improved thread fit where required. Use cutting fluid and correct spindle speeds when running in a lathe or die head to prolong life and ensure clean threads.

Typical applications include maintenance and assembly work in automotive repair, general engineering, plant and machinery maintenance, instrumentation and model engineering, and small‑component manufacture. It is widely used where replacement fasteners are made on site, or where damaged threads need re‑cutting.

Key benefits of the HSS die nut are its wear resistance and ability to retain hardness at elevated temperatures compared with carbon steels, giving longer life in production use. While HSS is not stainless, the bright finish provides moderate corrosion resistance; for highly corrosive environments consider coated versions or stainless tooling alternatives. The die nut is compatible with standard M4 nuts and bolts and conventional die stocks, making it a straightforward addition to workshop tooling.

Duchy Fasteners stocks a full range of metric die nuts and dies across common sizes; the M4 × 0.7 die nut is available individually and in small multi‑packs — please contact us for available finishes, holder options and pack quantities.