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.
Types of Countersink Cutters
- Cross-Hole Countersink Cutter: These have a hole that goes through the side of the cone that provides the cutting edge. These countersink cutters are suitable for deburring and can also be used in soft materials such as wood or plastic to create a countersunk hole. The design of these countersink cutters means that they are free from mechanical vibration or 'chatter' and they also stay in the centre.
- 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.
- Single fluted: These have less chatter or mechanical vibration than multi-fluted and are ideal for use in small holes for general-purpose countersinking, chamfering and deburring. These are designed for machine use and light portable work when operating at higher speeds.
- Three fluted: These are designed for a chatter-free performance and are used mainly in portable applications at slower speeds. The design of these countersinks gives them a good centring ability.
- Four fluted: These have good radial relief.
- Five Fluted: These have a rugged design and the odd number of flutes minimises chatter.
- Six fluted: These are ideal for producing fast shearing cuts.
These countersink cutter drill bits are made from HSS (High-Speed Steel) which can withstand high temperatures without losing its hardness.