noscriptCountersink Drill Bits | Countersinks | Cromwell Tools


Are you looking for general-purpose solid carbide countersinks you can rely on for your next project? Get most jobs done with carbide countersinks from expert brands you know and use all the time such as Kennedy, Dormer or Trend. Whether you're countersinking tool steel, cast irons, high silicon aluminium, bronze and non-metallic materials such as resin fibre glass and laminates, you can be sure that quality is always part of the process.

No matter the job, browse our carbide countersink range to find the exact solution for your project. The range boasts various cutting diameters that go from 1.5mm all the way to 31mm for high precision chucks. Our solid carbide countersinks are available in both three-flute with eccentric relief and six-flute with conventional relief, so you can choose the option that suits you best.

Don't forget to check out our entire countersinks range for even more expert tools and solutions.

What are countersinks?

Countersinking is the process of enlarging the rim of a pilot hole to allow the head of the fastener (screw) to sit flush with the materials surface, resulting in a neat and smooth finish. To create the recess needed for the screw to sit flush a countersink tool is needed. These tools feature the necessary tip shape to enlarge the entrance of the pilot hole enough to allow it to sit flush with the surface.

Why are countersinks needed?

Countersinks are commonly used when working with hard wood surfaces and countersunk screws. These screws feature a flat top to the head section as opposed to rounded. If the screw is placed in a pilot hole without countersinking, the screw can cause damage to the surface of the wood as it bites into the material causing a raised and rough area around it.

Types of countersinks

Countersinks come in a range of types, sizes and angles, designed for a range of applications. Below Cromwell has listed some of the most common types as well as some of their individual features and benefits.

Fluted - The most common type of countersink, fluted countersinks feature one or more flutes, creating the cutting edge. Their design features a short shaft with a wider cylindrical head and a conical tip.

Cross hole - Cross hole countersinks feature no flutes but instead feature a hole bored through the conical tip at an angle. This hole forms the cutting edge as the cone rotates, with chips being evacuated through the hole. These types of countersinks remove stock quickly and tend to result in a smoother finish than their fluted counterparts.

Piloted - These tools are an all-in-one solution to drilling and countersinking. The drill portion drills the pilot hole and is followed through with the countersink portion of the tool. The countersink is adjustable meaning you can set the depth of the pilot hoe before the countersink creates the recess.

There are other types of countersinks that can be used with a hand tool for manual countersinking.

Considerations when choosing a countersink

There are several key factors to take into account when choosing a countersink to ensure you pick the right tool for your requirements. To help with this process we have outlined some of the most common points, to help with your selection.

The angle - Getting the angle of chamfer right for the fasteners they you will be using is the difference in the quality of the finish of the workpiece. To deep an angle and the screw can bite into the material leaving a rough damaged finish, too shallow and there will be an obvious gap around the head of the screw when it sits in the pilot hole.

The most common chamfer angles are 82° and 90° with most screws conforming to 82, meaning a 90° chamfer will suffice but there will be a slight gap around the edge.

Overall countersinks are available in the following chamfer angles 60°, 82°, 90°, 100°, 110° and 120° some more specialised screw heads match these angles so for the best results pick a countersink that matches the angle of the fastener you are using.

Material - As with drills and other cutting tools selecting the right material for the hardness of the surface to be cut is important. High-speed steel is a common choice for wood and softer materials whereas harder metallic substances require a hardened carbide tool.

Sizing - It might seem fairly obvious but selecting the correct size of countersink for the fastener being used is important for the finished article. With cutting diameters of 1.5mm all the way to 31mm available in the range you'll be sure to find the right sized tool for your requirements.


Which countersink bit do I to use?
Depending on your requirements, a different style of countersink will yield different results. Cross hole countersinks leave a smooth finish with a rapid removal of stock. In harder woods and materials fluted countersink provide a stronger cut. An all in one solution could be provided by a pilot bit however this will provide a rougher finish.