This M30 x 3.5mm (3") HSS split die is a round cutting die designed to cut or restore external metric threads of size M30 with a 3.5mm pitch. It is intended for use in a hand die stock or compatible machine die holder to form or repair threads on bars, studs and shafts where an accurate ISO metric thread is required. The “split” feature allows the die to be slightly adjusted for tighter or looser fit and to compensate for wear.

The die is manufactured from High Speed Steel (commonly M2 HSS) and is ground to a precision thread profile. It is supplied with a dark oxide finish to give basic corrosion protection and reduce friction during cutting. The thread form conforms to ISO metric thread geometry and is suitable for parts made to ISO 261 / ISO 965-1 tolerances; it is also compatible with DIN 13 and BS 3643 metric thread systems. The die produces a standard right-hand M30 x 3.5 thread and is sized to suit a 3" (approx. 75 mm) round die holder or machine die adapter.

Typical applications include mechanical engineering, plant maintenance, fabrication, automotive and agricultural repair where large-diameter metric threads are required or where damaged threads must be restored on-site. The tool is effective on mild and medium carbon steels, alloy steels, stainless steels (with correct cutting practice), aluminium and other non-ferrous materials. For harder or stainless materials, use cutting oil and reduced feed to extend tool life and achieve clean threads.

The key benefits of this HSS split die are its wear resistance and maintained cutting edge at elevated temperatures thanks to the M2 HSS material, and the split design which allows controlled thread fit adjustment and simplified re-threading of damaged studs. The black oxide finish offers limited corrosion resistance and reduces galling; the die is compatible with standard 3" die stocks and machine holders so it integrates easily into workshop tooling sets.

Duchy Fasteners stocks a comprehensive range of taps and dies including metric and Whitworth sizes; this M30 x 3.5mm split die is available individually or in multi-packs and is held in a variety of size options to suit both hand and machine use. Contact us for current stock levels and pack quantities.