Meet the Dormer Pramet A402 M3 HSS Straight Shank Subland 180 Degree Standard Length (X4D) Drill—an engineered solution for precise counterboring that delivers clean, repeatable clearance holes for standard metric threads. This drill is built for professionals who demand accuracy, durability, and consistent performance in both CNC and manual milling environments.

Precision geometry for flawless counterbores

The tool features a 118° pilot to guide entry with minimal wander, paired with a 180° counterbore profile to create a defined clearance pocket exactly where you need it. The pilot diameter and length are specifically tuned to produce the correct drilling diameter and depth for standard thread clearances, helping ensure reliable thread engagement and tight fits in your assemblies.

Robust, reliable construction

• Premium HSS material: Designed to cut across a range of workpiece materials—from steel and aluminum to stainless steel—without sacrificing edge life.
• Steam oxide finish: Reduces built-up edge and helps prevent workpiece material from sticking to the cutting edge, promoting smoother, cleaner holes.
• DIN 8376, standard length, straight shank: Compatible with common holders and collets, delivering stable performance in both CNC and conventional setups.
• X4D designation: Indicates a consistent, standard-length geometry that suits a wide variety of counterboring tasks without needing multiple tool changes.

Where it shines

This drill is ideal for creating counterbored clearance holes for metric-threaded fasteners in a single, precise operation. It excels in situations where you must flush a bolt or screw head against the workpiece surface while maintaining clean internal geometry and accurate thread engagement. Use cases span automotive, aerospace, fabrication, and general engineering applications where reliable hole sizing and edge quality matter.

Why choose this Dormer Pramet drill over alternatives

Beyond basic drilling, this tool couples a purpose-built pilot with a dedicated counterbore feature to reduce drill wander and improve hole concentricity. The steam oxide finish minimizes adhesive buildup, allowing longer tool life and fewer interruptions on repetitive jobs. Its straight shank and standard-length geometry provide dependable performance in both CNC machines and traditional milling setups, giving you a versatile option for mixed-tool environments.

Practical tips for best results

• Use coolant or lubrication to maximize edge life and maintain finish, especially on harder materials.
• Start with a light pecking feed to seat the pilot before full-depth drilling, reducing dwell and chatter.
• Ensure proper workholding to prevent deflection—counterboring requires stable material to maintain diameter accuracy.
• Match the drill speed to the material type and hole depth; deeper counterbores benefit from slightly reduced speeds and increased lubrication.