The Dormer Pramet A402 M8 HSS ST Straight Shank Subland 180 DEG Standard Length (X4D) drill DIN 8376 is purpose-built for clean, precise counterbores and through-holes in metric screw assemblies. With a 118° pilot and a 180° counterbore, this tool is designed to deliver a ready-to-seat clearance hole and a defined screw head pocket in a single, efficient operation.

Key features that matter in real-world machining

• 118° pilot and 180° counterbore—engineered to create both the pilot hole and the counterbore in one pass, ensuring a consistent seat for M8 socket-head screws and a flat-bottom pocket for a reliable, flush screw head.
• DIN 8376 compliant—built to exacting standards for subland drilling, guaranteeing compatibility with common metric fasteners and other DIN 8376 tools.
• Straight shank, 4XD standard length—a robust, versatile design that works across CNC and conventional machines, providing dependable rigidity and reach for through-hole applications.
• 9.00 mm pilot diameter, 19.00 mm pilot length, 15.00 mm large diameter—precise dimensions that yield the correct clearance drilling diameter and depth for standard threads, with a defined land for a clean bottom seating area.
• Steam tempered finish (steam oxide)—reduces built-up edge on the cutting edge, helping to maintain cutting efficiency and prolong tool life when drilling free-machining steels, plain carbon steels, alloys, aluminum, stainless steel, and grey cast iron.
• Premium HSS material—high-speed steel offers a balance of hardness and toughness, making it suitable for a range of common workshop materials while delivering dependable performance in repetitive hole-making tasks.

Why this A402 M8 drill stands out

The combination of a precisely defined pilot and counterbore means you can achieve accurate hole diameters and a perfectly countersunk seating surface in a single operation, which reduces cycle times and minimizes the risk of misalignment. The 180° counterbore angle is specifically chosen to seat standard metric fasteners securely, preventing play and ensuring a consistent joint when assembling components.

Ideal use cases

• Creating clearance holes with an integrated screw head seating surface for M8 fasteners in steel, aluminum, stainless steel, and grey cast iron components.
• Production environments where CNC or conventional drilling centers need reliable, repeatable subland drilling in DIN 8376-compliant tooling trays.
• Applications requiring a single-pass approach to both pilot hole and counterbore, streamlining setups and reducing tool changes.

Practical tips for best results

• Follow a conservative feed and speed strategy suitable for HSS and the material being drilled; maintain steady, even motion to avoid scarfing or chatter at the counterbore transition.
• Use appropriate coolant or cutting fluid to reduce heat and help evacuate chips from the counterbore area, especially when working with steel alloys or stainless steels.
• Ensure the workpiece is firmly clamped to minimize deflection and maintain hole concentricity with the counterbore pocket.
• Inspect the drill after a set of holes for any edge wear; re-sharpen or replace as needed to preserve dimensional accuracy for subsequent operations.