Drill Bits Buying Guide...
The very earliest concept of a drill bit pre-dates history. The basic need for man to construct brought with it the requirement to create holes and sockets. It is believed that the earliest drill bits were simply sharpened flints pushed into the ends of sticks and rotated by hand or by a bow. Today's drill bits are somewhat more sophisticated although their function remains the same. With the development of different metals and technologies, different styles of drill bits have been introduced to drill and bore in all kinds of materials.
Anatomy of a Drill Bit
Despite the many different types of drill bit, there is a collective list of features that are common to all or most bits. By recognising the functions of these features, it becomes easier to understand how the drill bit actually works.
Fundamentally, a drill bit is a sharpened cutting tip mounted on a shank that is rotated to bore into wood, metal, stone and many other materials. At the cutting end of the drill bit a point or spur locates the bit in position and the cutting lips shear, scrape or tear away the wood, depending on the type of bit.
Some drill bits such as brad point bits and auger bits feature sharp cutting spurs on the outside edge of the bit that severs the wood fibres leaving a clean edged hole.
Starting from this cutting edge a flute or channel spirals its way up the body of the drill bit. This flute allows the waste to escape and helps to prevent the bit from clogging. ©
Types of Drill Bits
Twist Drill Bits
Twist drill bits are the most widely available and commonly used type of drill bit. Used for general purpose boring, twist drills are capable of drilling into both woods and metals. These bits normally have two helical channels running up the bit for efficient waste clearance. Due to the shape of the tip of the drill bit, twist drills have a tendency to skid or wander when initiating the cut and for this reason, it is recommended that an indent is made in the workpiece to seat the drill more accurately. ©View our Range of Twist Drill Bits
Brad Point Bits
Brad point bits or lip and spur bits, as they are also known, are used solely for drilling wood. Capable of producing holes with very neat edges, this type of bit is favoured when the finish of the hole is important. Easy to locate and drill accurately, these bits have a central spur which digs into the wood keeping the drill on course. Two sharp points on the outside edges of the drill slice the wood fibres rather than tear them leaving an extremely tidy hole and the cutting lips running horizontally on the bottom of the bit slice through the waste wood, removing it. ©View our Range of Brad Point Bits
The auger bit with its screw threaded spur and corkscrew like shape is ideal for boring deep holes and for use in a hand brace. The design of the auger means that it requires torque rather than a downwards force to move the bit through the wood. The threaded spur acts like a screw and pulls the bit into the wood keeping it on course for very accurate boring. This is followed by a sharp side spur which slices through the wood fibres to give a clean entry hole and finally the cutting lip which shears away the excess wood. The deep flute allows efficient clearance of the waste. ©View our Range of Auger Bits
The term Forstner bit is often used interchangeably with the term saw tooth bit. This is incorrect as the two, although similar, are different in how they cut. The Forstner bit is identifiable by its flat cutting edges which slice through the wood fibres keeping the bit straight during cutting. Sharp cutting lips shear away the wood from the centre of the hole leaving a flat bottomed recess with smooth sides. Perfect for those drilling jobs when accuracy and finish is important. Due to their design, Forstner bits are best used on fixed machines such as drill presses and lathes. ©View our Range of Forstner Bits
Saw Tooth Bits
Although very similar to Forstner bits, saw tooth bits are distinguishable by their jagged cutting circumference. Saw tooth bits cut faster than Forstner bits but the quality of the cut is not as high. Ideal for clearing out recesses and mortices before final squaring up, saw tooth bits can save plenty of time in the workshop. Due to the nature of these cutters, it is recommended that they are used in static machines such as drill presses and lathes. ©View our Range of Saw Tooth Bits
Countersinks are used when there is a need to fit screws flush to, or below, the surface of the wood. Available with or without pilot drills, countersinks cut a neat conical hole that the head of a countersink style screw will fit in to. A counterbore is similar to a countersink, but rather than cutting a tapered hole, cuts a straight sided hole ideal for concealed screwing. ©View our Range of Countersinks
Designed for precision, hinge drill bits are used to drill pilot holes when fitting hinges and other similar hardware. Consisting of an outer, spring loaded guide sleeve and an inner, fine diameter drill bit, these hinge bits give much better accuracy when drilling; important when the drilled holes in the wood must match the holes on the hinges. ©View our Range of Hinge Bits
As the name suggests, plug cutters are used for making wooden plugs. Extremely useful for cutting plugs to conceal screw heads or to replace a knot or other fault in a wooden surface, plug cutters come in a range of sizes. When selecting plug cutters, remember to choose a drill bit that corresponds to the size of the produced plug. This makes drilling the hole for and fitting the plug much easier. ©View our Range of Plug Cutters
Features to Consider When Buying a Drill Bit
Some drill bits feature coatings that reduce the wear on the drill bit keeping it sharper for longer. Such coatings like titanium nitride and even diamond particles can extend the life of the cutting edge of the bit by many times. This is ideal if the bit is destined for heavy use. Coated drill bits can be resharpened however the process of sharpening will remove some, if not all, of the coating. ©
2. Type of Metal
The type of metal a drill bit is made of will determine how strong the bit is, how suitable it is for abrasive materials and how long the bit will remain sharp. High carbon steel is not as hard as high speed steel and will, therefore, not stay as sharp for as long. However, the softer high carbon steel is quicker to sharpen. Some drill bits have tungsten carbide tips and are ideal for very abrasive materials, such as MDF, as the tungsten carbide retains a sharp edge much longer than steel. For everyday home use, high carbon steel drill bits are more than adequate, for heavier professional use look for high speed steel and tungsten carbide bits. ©
Most drills feature a standard cylindrical shank for use in hand drills and powered drills. Other drill bits are available with a 1/4" wide hexagonal shank for use with quick change chucks that offer faster bit change than conventional drill chucks. Some heavier duty bits feature grooved shanks and are for use in SDS drills only. Consider what you will be using the drill bit for and how often you will be changing drill bits during the project before you select a drill bit. ©
Tips From the Experts
1. When a precise drilling depth is needed, always use a depth stop. Too deep a hole could ruin a project, a hole that is not deep enough is hard to extend accurately. ©
2. The flutes of some smaller diameter twist and brad point drills may become clogged in use. Withdraw the drill bit from the wood regularly when drilling to ensure all waste is removed. ©
3. When using twist drills, an indented mark where you need to drill will help to site the drill bit and prevent it from skidding or slipping. ©
4. For greater accuracy when free hand drilling use a drill guide. ©
Famag of Germany have been producing some of the world's finest drilling and cutting tools since 1865. Using the very latest manufacturing methods, every tool Famag produce is made with the highest quality materials to exacting tolerances. All styles of drilling bit Famag offer give absolute diameters; if you use a Famag 10mm drill bit, you'll get a 10mm diameter hole. The sheer quality and accuracy of Famag's cutting tools have made them the professional's choice the world over.View our Range of Famag Drill Bits
Dakota tools are sourced from some of the world's best tool manufacturers. Carefully selected by a panel of woodworking experts, each tool is inspected and rigorously tested. Only those tools that meet or exceed expectations are approved to bear the Dakota brand name. Offering a wide range of woodworking products, Dakota's mission is to provide high quality tools to all abilities of woodworker from the weekend home woodworker to the professional carpenter.View our Range of Dakota Drill Bits
Sharpening & Maintenance
The majority of drill bits can be sharpened and this should be considered before throwing away a dull bit and buying a new one. Bits such as augers, Forstner, saw tooth, spade bits and countersinks can all be re-sharpened using small, hand held oilstones and diamond stones. The parts that need sharpening on these are the cutting spurs or edges and the cutting lips. ©
Twist drills may also be resharpened when dull but due to the complex geometry involved it is advised to use a dedicated sharpening machine such as the Drill Doctor. This will ensure the best possible result. ©
Some drill bits are coated to keep them sharper for longer. When sharpening these types of bits, remember the coating will be removed also meaning the bits will not stay sharp for as long as they did when new. ©
Drill bits are prone to rust and corrosion. Keep drill bits clean and give them a regular light coating of tool oil. ©
When not in use, try and keep the drills in the boxes, sleeves or tubes they originally came in. This will help to protect the drills from getting damaged and prevent them from getting lost. ©
Discard any damaged or bent drill bits. ©