This product is a 1/2" UNF right-hand split die manufactured in High Speed Steel (HSS) for cutting, restoring or sizing 1/2"-20 UNF external threads. Its primary use is for on-site thread cutting and repair where controlled, adjustable thread form is required — typically used with a compatible 1 1/2" die stock (holder) to produce or chase external Unified Fine threads on shafts, studs and bolts.

The die is made from HSS (commonly M2 grade), hardened and ground to provide wear resistance and cutting life when working with mild and alloy steels, non‑ferrous alloys and most machineable materials (not recommended for hardened steels above typical tempering levels). The tool carries a split configuration: the die body is slotted to allow slight adjustment of the thread fit by tightening or backing off the clamping screws in the die stock. The thread form produced is Unified National Fine (UNF), 1/2"-20 tpi, right‑hand cut, conforming to the UNF profile as defined by ANSI/ASME B1.1 for unified inch screw threads. The die is supplied with a ground face and a protective black‑oxide/finished surface to reduce light corrosion and improve chip flow during cutting.

Typical applications are in automotive maintenance and restoration, general engineering workshops, plant maintenance, agricultural machinery repair and toolroom work where a reliable imperial fine thread is required. The split die format is especially valuable for rethreading damaged studs, adjusting thread fit to suit mating nuts, or producing a controlled class of fit on-site without specialised machinery.

Key benefits include the cutting durability of HSS for longer life versus carbon tool steels, the adjustability of the split design to control thread tightness and repair capability, and compatibility with standard 1/2"-20 UNF fasteners and common die stocks. The tool provides consistent thread form to ANSI/ASME UNF standards while the finish offers modest corrosion protection during storage and use.

Duchy Fasteners stocks a broad range of imperial split dies and matching die stocks; this 1/2" UNF split die is available individually and as part of multi‑size sets, with pack quantities and alternative sizes available on request.