Dormer Countersinks

Dormer Countersink cutter drill bits are designed to fit directly into manual, electric, and cordless drill driver attachments and have hexagonal or round shanks. Countersink cutters are used to create a chamfer around the rim of a pilot hole enabling the head of a countersunk screw to sit flush. Countersink cutters can also be used to remove the burr left from a drilling or tapping operation.

Dormer's Fluted Countersink cutter:

These have fluted blades that produce a heavy chamfer to create the correct seating for a countersunk-head screw. Countersink cutters are available with six different cutting angles but the most common are 82° and 90°. The number of flutes on the countersink cutter can also vary.

Three-flute countersinks are commonly used in woodworking and metalworking for deburring, chamfering, and countersinking holes.

Here are three primary purposes for which they are used:

• Deburring: After drilling a hole, especially in metal, there might be burrs or rough edges around the hole's entrance. The three-flute countersink can be used to remove these burrs, ensuring a smooth finish, and preventing any interference with screws or fasteners that will be inserted into the hole.
• Chamfering: A countersink can create a chamfered edge around the top of a hole. This chamfer provides a bevelled entrance to the hole, making it easier to insert screws or bolts without damaging the threads. Chamfering also helps prevent cracking or splintering of wood when screws are driven into it.
• Countersinking: This is the process of enlarging the opening at the top of a hole to accommodate the head of a screw or bolt so that it sits flush with or below the surface of the material. This is essential for creating a smooth, even surface, especially in woodworking and metalworking applications where aesthetics or aerodynamics are important.