A 10 mm x 1.25 fine HSS dienut is a circular external thread cutting die intended for restoring or cutting M10 × 1.25 metric fine threads by hand or in a die stock. Its primary use is to produce or renew precision external threads on bolts, studs and shafts where the finer 1.25 mm pitch is required instead of the coarser M10 × 1.5 pitch.

The die is manufactured from M2 high speed steel (HSS) and is precision ground to maintain cutting geometry and wear resistance. It is supplied with a bright finish and a light protective oil coating to reduce surface corrosion in storage; for extended life in production consider using appropriate cutting lubricant. The thread form corresponds to ISO metric profile and is suitable for use to the tolerances described in ISO 965 and BS 3643 for metric threads, making it compatible with standard metric nuts and gauges.

This dienut is intended for use in a match die holder or hand die stock; it has the standard circular die shape with an adjustable split or set-screw arrangement allowing a small relief for slight thread fit adjustments when used in a die holder. As an HSS tool it is suitable for cutting into mild and medium carbon steels, alloy steels and some stainless steels when using proper speeds and cutting fluid. It is not a substitute for coated or carbide tooling where extreme production rates or very abrasive materials are involved.

Typical applications include automotive and motorsport maintenance (wheel studs, suspension components), precision engineering and instrumentation, hydraulic and pneumatic fittings, and general workshop maintenance where fine-pitch metric threads give improved clamp-up and vibration resistance. The key benefits are the inherent toughness and wear resistance of M2 HSS, accurate ISO/BS metric thread form compatibility, and the ability to re-cut or repair threads on-site with standard die stocks.

Duchy Fasteners stocks a range of dienuts and dies in metric sizes; the M10 × 1.25 dienut is available individually and in multipacks—please check our current stock list for available sizes and pack quantities.