Types of Drill Bits – Complete List and Guide 2021

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types of drill bits

Many DIY applications require the use of power drills.

This useful tool can handle a multitude of tasks, including drilling, driving, buffing, and sanding.

While you can buy some hand drills with a drill bit or two, other sets include more bits for various applications.

Having a collection of various drill bits enables an increase in the number of tasks you can accomplish with a hand drill.

Learn about the types of drill bits and associate them with their specific uses to know which ones you will need for your next DIY project.

What Is a Drill Bit?

what is a drill bit

A drill bit is a metal object that attaches to and moves in a rotary motion at the end of power drills.

It comes in many shapes that typically have a circular or symmetric cross-section.

Drill bits also come in a range of standardized sizes with circular or hex shanks.

Some drill bits have reduced shanks, which means the cutting portion has a larger diameter than the part attached to a drill.

Most familiar drill bits are made of steel, but some combine different metals for particular tasks.

How do you identify a drill bit?

You can identify a drill bit by looking at its physical characteristics.

Wood bits typically come with central spur points for guiding the bit into the wood without sliding or slipping to a different part of the material being cut.

In addition to the central spur point, wood bits have a lip.

This part acts like a chisel that slices through the wood fibers along the drilled hole circumference.

The lip ensures that the finish of the exit hole is smooth and does not have any splinters.

On the other hand, metal drill bits do not usually have a sharp, pointed spur point. Instead, they have a slight angle at the tip.

Drill bits for masonry have blunt carbide blades at the tip that typically protrude outside the shank diameter.

Different Types of Drill Bits

different types of drill bits

Let’s take a look at all the available drill bits for various DIY applications.

You can classify drill bits into four clusters depending on their intended material of application.

General Purpose Bits

General-purpose bits, also called universal bits, can be used for drilling wood, metal, plastic, and other materials.

Twist Bits

Also called high-speed steel (HSS) bits, twist bits have a cylindrical shank that ranges in diameter from 0.8 mm to 12 mm.

Although standard twist bits are made from stainless steel, durable twist bits are made with tungsten and vanadium.

You can use any of these for drilling holes through steel.

Twist bits are also considered general-use drill bits because they can drill through wood and plastic.

Step Bits

Step bits are for making holes of various sizes.

They have a stepped, conical shape that makes them ideal for making variable-sized holes and enlarging existing thin material holes.

Step bits typically have a titanium nitride outer layer that prevents heat build-up due to friction during operation.

Hole Saw

Hole saws are hollow cylindrical bits with a central shank that acts as a spur point.

Unlike most drill bits, hole saws cut a whole circular disc and leave a big hole on the material being cut.

You can use hole saws on wood boards, sheet metal, and other thin materials.

Wood Drill Bits

The following drill bit types have characteristics that give them the upper hand when drilling on wood surfaces.

Brad Point Bits

Brad-point bits are also called spur points, and they look similar to twist bits. However, brad-point bits only work well on wood and plastics.

Its tip has sharper points, one being in the center for keeping the whole bit centered while drilling.

Brad-point bits come in sizes between 3 mm and 10 mm.

Spade Bits

Spade bits have a spur point at the center and spade with carving spurs on either side. This type of bit is used for drilling large holes through wood.

Spade bits usually have hex shanks for a tighter grip in the drill chuck. They come in sizes that make holes with diameters between 6 mm and 38 mm.

Auger Bits

Like brad-point bits and spade bits, auger bits are for drilling holes into wood.

Wood auger bits are longer and are used for boring holes into bulkheads and general timber applications.

An auger bit is designed to pull itself into the wood using the spiral head, reducing the need for excessive pressure.

Forstner Bits

Another type of drill bit for wood is the Forstner bit.

Forstner bits were invented not for drilling holes but for making round indentations on wood for holding concealed hinges.

They can make round indentations with diameters measuring anywhere between 26 mm and 35 mm.

You use Forstner bits in drill presses for applications that require overlapping holes.

Self-Feed Bits

Self-feed bits look like Forstner bits on the outside, but they are actually hollower on the inside.

The pilot point of a self-feed bit is a screw tip that feeds the whole bit into the workpiece.

This drill bit does not have wide flutes, which means you have to pull it back occasionally to remove carved material and dust.

Plug Cutter

Furniture makers use plug cutters to conceal screw heads under the surface of the wood.

The plug cutter bit has one part that drills a hole and a second part that cuts a plug with the exact dimensions as the hole.

Unlike brad-point bits, plug cutter bits do not have spur points and may require a center press for accurate cuts.

Adjustable Wood Bit

Wood bits can also come with adjustable cutting edges mounted above a central pilot bit.

Also called expansive wood bits, adjustable wood bits can make holes with varying sizes.

These expand from the central point to the maximum length of the cutting edge attachment.

Metal Drill Bits

Metal drill bits are specially designed to cut through various metals, such as sheet metal and metal plates.

Center and Spotting Drill Bits

Center and spotting drill bits have a special use in metalworking.

You can use them for making holes for lathe centers or for spotting hole centers.

Lathe or hole centers are starting holes for larger-sized drill bits or conical indentations at the end of a workpiece.

Annular Cutter

Like hole saws, annular cutters are hollow cylindrical bits.

They leave an annular cross-section on the material being cut, leaving the inner cylinder intact.

In simpler terms, the annular cutter carves a whole solid cylinder, also called the core, from the material being cut.

Core Drill Bits

Core drill bits are a more major classification for annular cutters.

While its primary purpose is to enlarge holes, some are used to extract metal cores from solid metal workpieces.

When enlarging holes, the base material is often transformed into scrap metal pieces.

The core extracted using annular-type core drill bits is a clean, solid cylinder you can use as another workpiece.

Countersink Bits

Some screws and rivets have flat heads designed to flush with the surface of a material being fastened.

You need to create bevels on the rivet pilot holes to flush them with the material. To do this, the best thing you can use is a countersink bit.

Countersink bits come in diameters of 13 mm, 16 mm, or 19 mm. They can be made from varying materials for drilling on wood and metal.

Ejector Drill Bits

To drill deep, medium- to large-sized holes in solid metal pieces, the best drill bit to use is an ejector drill bit.

Ejector drill bits have specially designed carbide cutters at the tip and a small tube within a larger one.

With flushing water that travels down between the two tubes, chip material is ejected through the center of the bit.

Rivet Bits

Rivet bits may refer to one of two things.

The first type of rivet bit is ideal for drilling shallow holes through thin metal sheets.

It is shorter than standard drill bits and comes in varying diameters for different sized rivets. Its shank is typically hex-shaped.

The second type of rivet bit refers to highly-specialized, thumb-size bits used for drilling short, thick rivets into thick metal plates.

Its application caters more to large-scale steel construction applications rather than home-based DIY projects.

Other Materials and Specializations

Most general-purpose bits, wood bits, and metal bits cannot drill through masonry, tiles, and glass.

Additionally, other highly-specialized drill bits have more specific purposes that only they can deliver excellently.

Masonry Bits

Its name clearly suggests it is the type of drill bit used for masonry materials, such as concrete, stone, and bricks.

Masonry bits are another variation of twist drill bits.

These drill bits efficiently make holes into masonry with the help of a drill’s hammering action.

Masonry bits range in diameters between 4 mm and 16 mm, and the thickest ones can be as long as 400 mm.

The tip of masonry bits is made of tungsten carbide. Better versions have hexagonal shanks for chuck slippage prevention.

Hammer Bit

A hammer bit is a masonry bit used to make test holes in precise locations on concrete slabs using hammer drills.

Concrete slabs require some tests for safety before space can be deemed safe for human use or habitation.

Tile Bits

Typical tile bits have spearhead-shaped tips made of tungsten for drilling into ceramic tiles. They also work well on porcelain materials.

Tile bits require wetting the tile surface periodically while drilling. Doing this will ensure that temperature levels are low so that the tiles will not break.

Glass Bits

Glass drill bits have spade-shaped tips with a carbide point.

These bits drill holes at low speeds in a succession of increasing bit sizes to make holes on the glass.

Glass bits are not so durable because they generate extremely high temperatures while drilling.

Installer Bits

Installer bits are a variation of twist bits with a transverse hole near the tip.

They are usually longer and are used for drilling holes through walls and wood frames that allow cable installation.

Once a hole is drilled using an installer bit, a wire can be threaded through the transverse hole at its tip.

This added feature allows the user to pull the wire through the drilled hole using the drill bit tip.

PCB Through-Hole Drill Bits

Printed circuit boards are made of fiberglass. General-purpose drill bits have diameters too large for drilling holes in them.

Additionally, fiberglass is highly abrasive, and it can easily damage steel drill bits.

PCB through-hole drill bits are tungsten carbide twist bits very small in size, typically having diameters of 1 mm or less.

Tungsten carbide PCB bits can withstand wearing and tearing while cutting through fiberglass.

What’s more, they can last 10 times longer than standard steel bits.

What is the best type of drill bit?

The best types of drill bits are made of materials such as titanium and cobalt.

While standard general-purpose bits are made of high-speed steel (HSS), drill bits made from other materials offer better features.

Gold oxide bits provide increased durability and three times more speed for general purpose drilling in metals, wood, and plastics.

Black oxide bits are also high-speed steel bits. They have added heat treatment to reduce friction between the workpiece and the bit.

Compared to standard high-speed steel bits, black oxide bits offer 50 percent more durability and lifespan.

Cobalt and titanium bits are also made with high-speed steel, but the material is combined with cobalt or titanium nitride.

Special formulation cobalt bits are capable of enduring ultra-high drilling temperatures caused by friction.

Titanium bits are high-speed steel bits coated with a thick layer of titanium nitride that gives the bit exceptional hardness for penetrating rigid materials.

The titanium nitride coating also makes it resistant to corrosion and friction.

Conclusion

When getting a set of drill bits for your DIY project, make a list of the different materials that need drilling.

Then, determine what sizes you will be needing.

Do not stop at choosing drill bits based on their specialization for materials such as wood, metal, plastic, or masonry.

Some woods and plastics are denser and thicker than others, and metal plates are thicker than sheet metal.

Also, masonry materials come in different compressive strengths, making particular concrete objects denser and tougher to drill than others.

The types of drill bits you should get must also be appropriate for the kind of material you plan to drill.

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