noscriptHigh-Quality Drilling Tools | Cromwell UK


Cromwell stock a wide range of hole making tools designed for all drilling applications available as individual drills or as part of a drill set. With well-known brands like Dormer and Kennedy, you'll be sure to find the right tooling solution for your individual needs and application.

What is drilling?

Drilling is cutting application that utilises a drill bit to cut a circular hole in hard materials. The tool works by rotating and is pressed against the surface of allowing its cutting edges to cut through the material creating chips. Drills are available in many types and sizes with metric and imperial measurements available.

When are drills used?

Drills of some description are used in the majority of hole making applications. On e of the most common types of drill is the twist drill which features 2 or more flutes arranged in a twist allowing chips to be evacuated efficiently. They are commonplace in drilling machines and versions of them are used with handheld power tools for everyday domestic use.

Depending on the type of cutting application more specialised drill can be used. For example, drilling sheet metal requires the use of a step drill which is named because of its conical tip that resembles the steps of a pyramid. These types of drills allow precise hole making of varying diameters.

When drilling hardened metals, then carbide drills can be employed. These types of drills are made from a tungsten carbide compound instead of the standard steel alloy or high-speed steel and feature a harder, sharper cutting edge. Their drawback is that they are more expensive and less resistant to breakage through knocks and being dropped and as such are usually reserved for specialist usage.

Types of drills

There are a wide variety of drills and hole making tools, suitable for different industries, applications, and levels of experience available as individual drills or part of a drill set. To help with the tool selection process Cromwell has outlined a selection of the most common types.

Jobber Drills - The most common type of drilling tool, also known as a twist drill comes with a multitude of variations of its own. These versatile, general-purpose drills have a standard length that balances between strength and reach, suitable for a wide range of materials and applications making them ideal for various drilling tasks in metal, wood, and plastics.

Long series drills - These are a longer length version of jobber drills, sometimes known as aircraft drills. The extended length allows them to drill deep holes with a smaller diameter.

Stub Drills - Short and robust, designed for drilling shallow holes with high precision and minimal deflection. Their short length makes them less prone to breakage and ideal for applications in tight areas.

Carbide Drills - made from carbide material, offering exceptional hardness and heat resistance for drilling tough materials like stainless steel and cast iron. They maintain their sharpness longer than high speed steel drills, making them suitable for high volume production and hard materials.

Masonry Drills - Designed for drilling into hard materials like brick, concrete, and stone, featuring a tungsten carbide tip that are often fluted to help remove debris and prevent the drill bit from overheating.

Taper Drills - Used to create tapered holes, which can be used for aligning components or preparing holes for tapered fasteners. They gradually increase in diameter along their length, allowing for precise control over the hole size.
Step Drill - Named because of its conical tip that resembles the steps of a pyramid, these types of drills are ideal for drilling sheet metal as their specialised tip allows both variation and accuracy of sizing.

Replaceable head/insert - These drills feature a body tool with either a replaceable head or individual cutting inserts that make up the part of the tool that actually does the cutting. They are widely used in specialist industrial applications. An advantage of this is that the entire drill doesn't need replacing when the cutting edge has become dull, however they tend to be costly items so they are rarely used outside of industrial machining.


What drilling bit do I need?

This is primarily dependant on several factors, what material you are drilling, what size hole you are drilling, what type of hole you are drilling and how many workpieces you are drilling.

The material being drilled will determine what hardness of drill you will need, for example wood and softer metals or materials would probably require high speed steel, but for hardened materials such as tool grade steel then high-speed steel might result in a dulled cutting edge and a reduction in the tool lifespan. Carbide drills are better at retaining their sharpness and are used to cut harder materials such as hardened steel.
Sizing is also a key component, drills are available in a range of diameters and lengths with imperial and metric measurements. Making sure the size of the hole matches the size of the fastener is also paramount.

There are also different types of hole that different drills are designed for. A simple pilot hole can be drilled using a twist drill, however centre drilling applications requires the use of a centre drill as these are designed to be operated on a lathe chuck.

In the case of large scale industrial drilling a replaceable head or insert drill might be more appropriate as these machines are designed for rapid machining applications with little down time.