This 12mm rosehead countersink bit HSS is a purpose-made cutting tool for producing neat, conical recesses and deburring hole edges so countersunk screws sit flush with the work surface. Its primary use is to create a clean 90° chamfer around drilled holes in metal, wood and plastics, preparing faces for countersunk fasteners and improving finish quality before assembly or painting.

The cutter is produced from M2 high‑speed steel (HSS) and supplied with a bright ground finish. The tool geometry gives a nominal 90° cutting angle suitable for standard countersunk screw heads and conforming to common ISO and BS countersink profiles; it is made to general industry dimensional conventions (DIN/ISO/BS) for countersinking tools. The rosehead form features multiple cutting flutes to provide a smooth surface finish and efficient chip evacuation. The bit is intended to be used in standard drill chucks on hand drills, drill presses or powered countersinking attachments.

Typical applications include joinery and cabinet making where neat screw seats are required, metal fabrication and maintenance where holes need deburring and chamfering, electrical and plumbing installation for neat fixings, and general engineering and automotive workshops for through‑hole preparation. It is also useful in on‑site construction and maintenance tasks where a compact, versatile countersink is required.

Key benefits of the M2 HSS construction are high hot hardness and excellent edge retention, allowing sustained cutting performance at the speeds typical of hand and machine drilling. The bright ground finish reduces the tendency to gall and gives a consistent surface finish on workpieces. Whilst HSS provides strength and wear resistance, it is not stainless; users should store the bit dry to avoid corrosion, and reduce speeds/feeds when working with stainless steels. The bit is compatible with standard 3‑jaw chucks and most portable and benchtop drilling equipment.

Duchy Fasteners stocks this 12mm rosehead HSS countersink as single items and in small multi‑packs; we also carry a range of countersink sizes and similar power tool accessories—please contact us for availability of alternate diameters and pack quantities.