- Countersink drill bits are available in carbide or high speed steel. A variety of flute configurations and included angles are available. The 82 degree countersinks are commonly used where flat head fasteners, such as flat head socket cap screws, are designed to sit flush into the work surface. The six flute chatterless designs feature an uneven flute configuration, to reduce chatter and improve surface finish. The carbide countersinks (one of the most popular items in our offering) are oustanding for hard-to-machine and abrasive materials. These single, 3, 4, and 6 flute countersinks are available from stock in many diameters and included angles to accomplish almost any countersinking operation you may encounter.