What is a Drill Bit?
A drill bit is an interchangeable tool accessory for an electric power drill.
Drill bits help you to cut holes into materials cleanly and efficiently, saving you time while getting you the best result. You’ll find different drill bit types designed for different applications, such as drill bits for metal, screwdriver bit sets, and drill bits for wood.
The key to working with drill bits is knowing which types of drill bits you need for the job, so this guide will cover-off the different drill bit names and explain what each one is for.
Drill Bit Parts and Functions
The main parts and features of a drill bit include:
Brad Point
This is the front section of the drill bit that cuts into the material you’re working with. Within the brad point you have two other drill bit features: the Spur and the Cutting Lip.
Spur
The Spur is the centre of the drill bit’s point.
Cutting Lip
This part of the drill bit, right at the tip of the point, removes the material as the bit advances. This is the part that varies the most between different drill bit types.
Flutes
Also known as the Channel, the flutes are the section just past the Cutting Lip. These help to remove loose material.
Shank
The Shank attaches the drill bit to the drill. Depending on the drill bit type, the Shank will either clamp into a spindle or slot directly into the drill’s chuck.
Types of Drill Bits and Uses
1. Masonry Drill Bits
Masonry drill bits are designed for materials like brick, concrete, and stone. They feature a robust cutting lip, usually made from tungsten carbide on a steel shaft that’s powerful enough to cut through solid material.
As well as a rotating motion, masonry drill bits also use a hammering action to drive the bit through. Size-wise, these types of drill bits range from around 5mm to 16mm.
2. Spade Drill Bits
Also known as Flat Drill Bits, Spade Drill Bits are designed for wood. This makes them an extremely popular tool with electricians, who use them to cut holes for cables to feed through.
Spade Drill Bits feature a sharp centre point and a distinctive flattened cutting lip. They offer a fast way to cut large-diameter holes in wood, however, the finished result is rough and often splintered around the edges.
Size-wise, Spade Drill Bits are measured in diameters of 10mm up to 32mm.
3. Auger Drill Bits
Auger Drill Bits are also designed for wood; however, they give a more accurate and precise finish than Spade Drill Bits. That’s because Auger Drill Bits feature a pronounced Spur that keeps the drill bit on course, resulting in holes with clean edges. Their corkscrew-like flute also helps to clear chips away quickly.
Auger Drill Bits are available from 8mm to 32mm and are a highly adaptable drill bit type with a range that spans everything from fine woodworking to flooring installation.
4. HSS Drill Bits
HSS Drill Bits (short for High Speed Steel) are heat resistant up to 500C and extremely hardwearing, making them ideal for projects involving metals, hardwoods, and plastics.
If you need to cut holes in steel, cast iron, and alloyed or non-alloyed metals, an HSS Drill Bit is the perfect bit to use.
5. Step Drill Bits
Step drill bits have a stepped or staggered point that widens towards the flute (similar to a spear’s tip). They’re designed for use with soft and thin materials, and are coated in titanium-nitride, which minimises heat transference while acting as a lubricant.
Step Drill Bits allow you to create a range of holes in different sizes, without needing to change your drill bit. They also come in handy if you need to widen or deepen a hole that’s been cut too small.
6. Drill Bits for Glass and Tiles
Drill bits for glass and tiles typically feature an arrow-like point, allowing them to create a neat and precise cut without cracking the glass or tile. Unlike other drill bit types, glass and tile drill bits shave material away and must be operated at a very slow speed using a coolant such as water or turpentine.
If you’re drilling through porcelain or other hard masonry you should instead use a Diamond Tile Drill Bit. To prevent the point from slipping, begin the cut at a 45-degree angle and then straighten the drill bit slowly.
7. Multi-Purpose Drill Bits
As the name implies, Multi-Purpose Drill Bits are suitable for a range of different materials and applications. This is a great all-round drill bit set to have in your tool arsenal as it gives you the flexibility to work with metals, masonry, plastic, and wood.
8. Mortice Drill Bits
Mortice Drill Bits are used for woodworking and cabinetry. They produce square holes and can be used to cut corners and slots in wood for mortise and tenon joints.
Unlike other types of drill bits, which fit into power drills, Mortice Drill Bits can only be used with drill presses and mortising machines.
9. Countersink Drill Bit
Countersink Drill Bits have a cone-shaped point. They’re used to bore a bevelled hole into wood or metal for screws, bolts, or other fasteners to fit into.
Countersink Drill Bits typically come in sizes 13mm to 19mm. The wood, metal, and fastener varieties differ, so if it’s important to check which drill bit type you need.
10. Hole Saw Drill Bits
Hole Saw Drill Bits are compatible with wood, metal, tiles, plastic, and – in some cases – even masonry. They cut large diameter holes but leave the core behind.
Hole Saw Drill Bits are easily identified by their circular serrated cutting blade, which pivots around their spur. They’re an ideal choice of drill bit for installing door hardware, and a little neater in their cuts than a Spade Drill Bit.
Drill Bit Shank Type Explained
The shank is the part of the drill bit that affixes to the drill. It sits at the opposite end of the drill bit point and comes in five key varieties, compatible with different chuck types:
Hex Shank – A six-sided shank, designed for electric screwdrivers and screw guns.
SDS Max Shank – A grooved shank suitable for heavy-duty jobs. It’s compatible with most hammer drills and some standard drills.
SDS Plus Shank – A slotted drive system, common with masonry drill bits.
Straight Shank – A smooth and circular shank, compatible with keyed or keyless drill chucks and drill bits of 10mm to 13mm.
Threaded Shank – A shank designed for hand-held drills or grinders that don’t have a chuck. Good for when you’re working in restricted or confined spaces.
Screwdriver bits: Which one do I need?
Screwdriver bits, like drill bits, come in a variety of styles. Which type of screwdriver bit you need depends entirely on the type of screw you need to remove or fasten.
The main screwdriver bit sets we stock at Red Box Tools are:
Slot Bits
Slot screwdriver bits have a flat, blade-like, point that looks a little like a chisel. They are compatible with single slotted screws.
Philips Bits
Philips screwdriver bits have a slightly tapered and pointed tip. They fit Philips screws, which feature a small, plus-like, shape at their centre.
PoziDriv
PoziDriv screwdriver bits have a blunt tip and parallel flanks. They’re compatible with Pozi screws, which are almost identical to Philips screws except for an extra set of grooves.
Square Bits
Square screwdriver bits are square-shaped and fit screws that have a square-shaped screwhead slot. They’re mostly used in electrical work.
Star Bits
Star screwdriver bits (also known as Torx bits) are star shaped. They fit with star-headed screws, commonly known as Torx screws.
Popular drill bit sets
At Red box Tools we stock all types of drill bits from a range of top-name manufacturers.
Our extensive collection includes drill bits for wood, drill bits for metal, and screwdriver bit sets, to name but a few. Here are just a few of our most popular drill bit sets from our professional drill bit range:
BAHCO 228-SET-SD
HSS STEP DRILL SET – 3 PCS
BAHCO 4513-SET-19
HSS-G DRILL SET FOR METAL – 19 PCS
BAHCO 9629-SET-8
FLAT DRILL BIT SET FOR WOOD – 8 PCS
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