There are many drill bit types which are designed to drill holes in a variety of materials. Common materials include different types of wood, metal, concrete and ceramic tile.
I have been using drills and other power tools for over 30 years. I have experience working with a variety of materials and know which tools are best for the job.
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Most guides online only go into the most well-known drill bits. In the below guide I have described 10 drill bits and their uses. Some drill bits have many purposes and so I’ve also given pros and cons to using each drill bit.
All About Drill Bits
Each drill bit has a specific tool geometry, differentiating it from the others. Drill bits vary by the length of bit, presence and rate of spirals, angles as well as the material.
Within this section I shed light on why these elements are so crucial in the performance of drill bits.
When it comes to drills and bits, there are two main parts – the shank and the chuck. The shank is the end of the drill bit that connects to the drill. The chuck (part of the drill) secures the bit. Small hand drills have around a ¾ inch chuck whereas for larger machines it’s closer to ½ inch. The size of the chuck limits the size of the compatible drill bit.
The size of a drill bit reflects the diameter of the body (rather than the length of the bit). The diameter determines the size of the hole being drilled.
Bit sets typically include 1/16 inch bits to ¼ inch. Smaller bits can be used for drilling holes to hang pictures. Larger bits can be as large as ½ inch and can be used to make way for copper pipes.
The material of the drill bit determines the type of material capable of being drilled into. Some materials can drill into a variety of materials but also have pros and cons. This can affect the performance and life cycle of the bit.
Some materials are also just a ‘coating’ on top of steel.
Common materials include:
- HSS (or High Speed Steel). This is one of the most common materials used in drill bits. HSS is universal and capable of drilling through wood, fiberglass, polyvinyl chloride (PVC) and other softer materials.
- Cobalt. Cobalt bits are a combination of steel (or another alloy) with a small percentage of cobalt. This is typically 5% or so. Cobalt is very hard and has an extremely high melting point of 1495°C. It is suitable for use on hard metals such as stainless steel and aluminium.
- Black Oxide Coating. This is a coating over HSS. Black Oxide Coating bits offer the same versatility as HSS with added advantages. The lifespan is 50% longer than HSS. Black Oxide also offers corrosion prevention and increased durability.
- HSS bits coated with titanium offer versatility with added benefits. The coating is extremely hard and allows penetration through tougher materials. This prevents less friction. Titanium also lasts far longer than HSS, potentially as much as 6x longer.
- Carbide-tipped drill bits are used for drilling tile and masonry. They are tough bits with a very hard head, making them more resistant to extreme loads.
Drill bits are made in different shapes and sizes. In the case of the spirals, a compact flute is required to remove a large volume of the piece and an elongated flute is used to remove a small volume of the piece. Depending on the functional length of the drill bit, you can create deep or close to surface holes.
Besides these two characteristics, the angles of the drill bit are also important. The angle of the bit determines what materials can be drilled.
Flatter (such as 135 degree) angles are used for harder materials such as masonry and tiles. Often a flat drill head is harder to control and you might need a pilot hole to keep the drill bit from wandering.
Steeper points (such as 118 degree) are best for softer materials. Steeper angles stay on center better and produce cleaner entry and exit holes.
Different Types of Drill Bit
Here I will detail the 10 most useful drill bits. Of note, there are some ‘all rounder’ drill bits that are more versatile in their use cases. These include twist bits and HSS bits. These bits are used on almost all materials. Besides these, drill bits are specialised and made for specific tasks. Examples of more precise requirements include extracting the core of a material or enlarging existing holes.
1. High Speed Steel (HSS) Bits
High Speed steel bits are also known as twist bits because of their cylindrical shank. HSS bits are the go-to drill bit for universal use.
HSS bits incorporate tungsten and vanadium in construction which provides good strength. They are also coated with titanium nitride.
HSS drill bits size ranges from 0.8mm to 12mm.
Suitable Materials: General use including steel.
- Serves multiples uses.
- Can drill through steel.
- Can be sharpened
- Compatible with electric, power, and hand drill.
- Small sized bits are fragile
- Can clog easily.
2. Brad Point bits
Brad point bits are like twist bits in shape and size. The main difference is in the tip. The tip is shaped like a “W”. This allows the sharp spike at the tip of the drill to cut sharply through material before the body of the drill makes contact. This means less resistance and a cleaner start to the hole.
Suitable Materials: Woodwork and plastic.
- Good for detailed work.
- Compatible with power, electric and hand drill.
- Precision cuts for wooden materials.
- Gives a neat finish.
- Not suitable for hard material.
- Hard to sharpen.
3. Auger drill bits
An Auger bit is a specialised wood-boring bit. A screw tip starts the hole and pulls through the remaining bit creating a clean hole. This means the user doesn’t need to exert excessive pressure. Auger bits are effective in drilling long holes in most types of wood.
The flutes are distant from one another. This results in the quick drilling of wood in substantial depth. It also means continued wood chip removal allowing for deeper boring.
Suitable Materials: Wood
- Effective in drilling long holes in a variety of wood materials.
- Efficient in cleaning wood chip waste.
- Designed for creating long holes only.
- Not flexible.
- Can only be used on wood.
4. Forstner bits
Forstner bits drill wide, smooth holes in wood. They are sometimes used for drilling flat-bottomed holes for receiving dowels, or concealing screws on hinges.
The design of forstner bits is unique. The bit is guided by the wide outside rim of the bit. This is opposed to other bits which are guided by the tip. The bit drills ‘outward in’.
Forstner bits create flat holes with precise depths. They are also used to create overlapping holes.
Suitable Materials: Wood
- Drills wide holes.
- Specialised for flat bottomed holes.
- Can be sharpened using diamond files and oilstone.
- Constant contact with wood overheats the drill.
- Non-versatile. Only suited to wood.
5. Hole saw
Hole saw drill bits are different to other bits. Rather than drilling through a solid chunk of material, hole saws will create a hollow cut.
The saw blade is a ring shape and creates a hole in the workpiece without cutting into the core. Typically, it has a built-in shank that includes an arbor. A hole saw can have two types of edge- the diamond edge and carbide edge.
Hole saws cut perfectly round holes in a variety of materials. Examples include installing drain pipes and creating holes for plumbing.
Suitable Materials: A variety – steel, aluminium, copper, plastics and wood. Not masonry or tiles.
- Cuts through ceramic, masonry, wood, and metal.
- More efficient than spade drill or twist drill.
- Doesn’t cut the core material.
- Can get stuck to the object
- Causes friction.
6. Countersink bits
A countersink drill bit is used for countersinking drill holes, screws and deburring. Countersinking widens the hole and facilitates subsequent tapping. For example, when screws are countersunk space is created for the screw head to be closer to the surface of the workpiece.
Unlike other drill bits, countersink bits are used to prepare material for drilling.
They have a tapered body and pointed tip.
Suitable Materials: Steel, brass, aluminium, plastic and wood.
- Compatible with power drill and routers.
- Can drill pilot holes.
- Can only be used on wood.
- Very specific purpose.
7. Plug Cutting Bit
Plug cutters fill any counterbore holes already created. They create perfectly sized plugs to match the project being worked on. The plug is then used to fill holes in wood. This is better than using wood filler as the end result is more solid and precise.
Plug cutters come in a 6mm, 8mm and 10mm diameter. The user drills into scrap wood to create the shape of a plug, then uses a screwdriver to remove the plugs from the wood.
Suitable Materials: Wood
- Creates perfectly sized plugs hiding the hole completely.
- Superior to using wood filler.
- Can’t be sharpened
- Serves only one purpose.
8. Stepped Drill bit
A stepped drill bit is not tapered and spiraled like other bits. It is a conical shape with stepped sides (similar to a Christmas tree). Traditional bits make holes in one size whereas the stepped bit can make and widen holes in a variety of sizes.
Typically a bit is limited to a size of ⅜ inch holes. Stepped bits may have a total of 9 different sizes with each step corresponding to a different measurement. The tip of the triangular shape may be a ¼ inch but the bottom may be as wide as ¾ inch.
The user determines the width of the hole being drilled. The further the drill is pushed, the wider the hole becomes. This bit is therefore not suited to creating multiple exact sized holes. But it’s good for widening existing holes.
Suitable Materials: A variety of thin materials.
- Compatible with wood and thin metal.
- Excellent for widening existing holes.
- Doesn’t overheat.
- Can be used for a specific purpose only.
- Can’t be sharpened.
- Won’t create consistently sized holes.
9. Spade bits
Spade bits are also known as paddle bits. They have a wide, flat blade and a sharp point at the centre. The central point acts as a guide, centering the hole and followed by the shoulder of the spade.
Space bits are mostly used for drilling large diameter holes in wood. One example is drilling holes in stud walls for running wire or pipes. They operate at high speed and shave wood out of the hole in a corkscrew type manor. The drilling action produces very long wood shavings.
Suitable Materials: A variety of woods and some plastics.
- Flat surface and sharp point.
- Creates neat finishes.
- Drills large diameter holes.
- Can be used on wood and some plastics.
- Can get stuck if used at low speed.
10. Titanium nitride HSS bits
The titanium nitride bits are titanium nitride coated HSS. This gives them a shiny golden look. Titanium nitride is an extremely hard ceramic material which offers great protection to the steel with extended performance life.
They are available in five sizes and hence are used on different materials. They are used on wood, plastic, and metal of any kind. Some titanium nitride drill bits will last longer than 6x standard high speed steel bits.
- Can be used for general purpose drilling as well as masonry.
- Durable and strong.
- Requires low maintenance.
- Doesn’t overheat.
- Hard to sharpen due to the coating
I don’t need to tell you how important drill bits are. But it’s important to note the huge variety of drill bits and their use cases.
Learning more about different types of drill bit and differences in shape and construction will help you make the right buying decision.
If you’re in the process of expanding your tool kit, check out this guide on what we think the most essential tools are.
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