Carbon Steel Adjustable Counterbore Bit

A robust, field-proven adjustable counterbore bit designed for accuracy and endurance in daily woodworking. With an 8mm shank and compatibility across five bore sizes — 2.8mm, 3.0mm, 3.2mm, 3.5mm and 4.0mm — it adapts seamlessly to varying fastener requirements. The core is made from solid hardened 45# carbon steel, while cutting edges feature YG6X micro-grain carbide for enhanced abrasion resistance. Every cutter is CNC ground to a mirror-like 600-grit finish, and the high hook/shear angle profile promotes clean, low-vibration cutting. An enclosed, factory-lubricated bearing ensures smooth rotation, and a Teflon coating protects against heat, resin, and corrosion. Ideal for custom joinery, kitchen cabinet builds, and repair work where precision and reliability cannot be compromised.