Dormer Pramet A402 M8 HSS ST STRAIGHT SHANK SUBLAND 180 DEG STANDARD LENGTH (X4D) DRILL DIN 8376

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.