Sutton 3mm Counterbore - DIN373 Cobalt Steel HSS-E

Sutton Tools is an Australian-owned manufacturer of precision cutting tools and threading accessories, supplying tradespeople, engineers, and manufacturing operations across Australia and internationally. Their product range spans taps, dies, drills, endmills, holesaws, and related tooling — all engineered to perform consistently under real industrial conditions. AIMS Industrial supplies the Sutton Tools range to Australian businesses as part of our commitment to stocking quality, trusted brands.

Sutton counterbores and spot facers produce flat-bottomed recesses for socket-head cap screws, cap bolts, and other fasteners that require a seated bearing face, or clean and face irregular surfaces around existing holes.

Where this product is used

Used in engineering workshops and maintenance environments for counterboring fastener holes and spot-facing mounting surfaces.

• Counterboring clearance holes in aluminium, steel, and stainless components for socket-head cap screws and hexagon socket bolts where the head must be flush or recessed.
• Spot-facing rough cast, forged, or welded surfaces around drilled holes to produce a flat bearing face for bolt head and washer seating.
• DIN 373 counterbore use in toolroom and jig/fixture making where precise flat-bottomed recesses are required to drawing specification.

Key specifications

Selecting the right option

Match the counterbore diameter and pilot to your fastener — the pilot diameter must fit freely in the clearance hole while the outer cutting diameter matches the fastener head size. For cobalt (HSS-E) counterbores, use at reduced speed in stainless and alloy steel with cutting fluid. Ensure the machine spindle is running true before counterboring — runout produces an oval or tapered recess.