The art of drilling various materials dates back to ancient times when early societies used crude instruments to bore out wood and stone. Today, the practice of drilling has evolved substantially, including the use of power tools and specialized bits. With such specialized equipment in hand, a tradesman can bore holes of virtually any size, at a rapid pace.
However, perhaps more important than a drill itself is the type of drill bit that is selected for use with the task at hand. A drill bit, if correctly matched to its intended use, has the tendency to save both time and effort, as it penetrates effortlessly into any stock being drilled.
However, an incorrectly selected drill bit often produces the opposite effect, creating a series of headaches along the way. This places increased importance on understanding the specific uses of particular types of drill bits.
Such understanding arms one with the knowledge necessary to accomplish most any tasks of the sort without any undue degree of difficulty. Read on to learn more about 41 different types of drill bits, and their specific uses.
Related: 30 Different Drill Types
Drill Bit Types
Twist Drill Bit
Drill bits of the “twist” variety are generally thought of as being general purpose in nature, due to their ability to bore holes in a wide variety of materials. Bits of this configuration typically feature 118-degree tips and are constructed of HSS (High-Speed Steel).
Though twist drill bits can be used on a variety of materials, they are seldom the most efficient bit for use in any specific application.
See Also: Top 3 Drill Bit Sets
Masonry Drill Bit
Also known as: concrete drill bit, hammer drill bit
Masonry bits are designed to penetrate through concrete, brick, and block. Bits of this type feature a blunt Tungsten Carbide tip, which is brazed or welded in place.
Masonry drill bits are typically used in conjunction with a hammer drill, and penetrate by use of crushing power, rather than cutting.
Auger Drill Bit
Auger drill bits are intended for use in low-speed, high-torque applications, and can be used in conjunction with a power drill or brace (by-hand). These bits feature a screw thread at their outer tip, which is followed by a much larger, knurled segment.
Auger bits are also known to produce extremely clean holes.
Glass Drill Bit
Glass drill bits feature a spear-shaped head, which is designed to bore through glass without causing a fracture. Care should be taken when using a bit of this nature, as glass bits often wander until a hole has been established. This can lead to a marring of glass surfaces.
Step Drill Bit
Step drill bits are conical in shape, and graduated in diameter, allowing users to quickly bore holes to a defined size. Bits of this type can also be used to clean out holes cut with various alternate types of drill bits.
Countersink Drill Bit
Countersink drill bits are used to create a recess for a screw head to sit within. Countersink drill bits come in numerous configurations, including star, rose, and snail.
The majority of such bits also feature a hexagonal shaft, allowing for expedited change out.
Self-Centering Drill Bit
Also known as: door hinge bit
Self-centering drill bits feature a chamfered drill guide which can be used to provide perfect alignment when drilling pilot holes for hinges, handles, and other trim accessories.
The guide itself is centered around a drill bit contained within, leaving little room for error when drilling into door frames. Simply insert the tip of your bit into the hole of your new door hinge, and drill with confidence.
Tile Drill Bit
Tile drill bits are relatively similar to those bits used when attempting to drill through glass. Tile bits take on a spear shaped appearance and are used to bore out holes of varying sizes.
However, tile bits can create irregularly shaped holes, when too much pressure is applied during the cutting process.
Spade bits, also known as paddle bits, are used when it is necessary to drill large holes in wood. Spade bits can drill holes as large as 1 ½ inches in diameter.
The spade bit is held in position by the sharp point in the center of the bit, thus allowing perfect circles to be cut.
Square Drill Bit
Square drill bits are yet another variant of the traditional mortising bit. These bits feature a spiral-shaped auger, contained within a hollow chisel-like shell.
When operated in a drill press or mortising machine, square drill bits simultaneously puncture and core wooden surfaces, leaving behind an expertly squared hole.
Forstner Drill Bit
Forstner drill bits are used to bore wider, flat-bottomed holes, which feature indented central points. Bits of this configuration can also be used to drill overlapping holes when deemed necessary.
The origins of the Forstner bit seem to have grown out of the early gunsmithing trade when it was initially used during stock design and fitment.
Hole saw drill bits are circular in shape and feature serrations around their outside edge. These serrations create a sawing motion as the bit is rotated by a drill, thereby cutting a clean hole of a specific size.
Care should be taken when using a hole saw bit, as they tend to bind, causing a drill to “kick” in the process.
Related: Hole Saw Size Chart
Flexible Drill Bit
Flexible drill bits are longer than many other types of drill bits, and feature shanks of spring steel, allowing them to bend when in use.
Bits of this type are used to drill awkwardly angled holes and come in handy when attempting to work around tight angles.
Coring Drill Bit
Coring drill bits are used to cut large holes in masonry and can be used with both standard and SDS drills. However, it is always important to drill as straight as possible when using a coring bit to avoid snagging, which can lead to hand/wrist injury.
Split Point Drill Bit
Split point drill bits are intended to drill on curved surfaces or in conjunction with alloy steels. Bits of this style are designed in a manner that prevents walking and improves penetration.
Split point bits are available in 118 or 135-degree angles, yet are difficult to re-sharpen and are more expensive than a standard drill bit.
Brad-Point Drill Bit
Brad-point drill bits, also known as a spur point, have the same shape as a twist bit only with a “W” shaped end. This allows the bit to start cutting the outside of the hole before cutting the inside.
Brad-point bits are a perfect choice for drilling both wood and plastic.
Counterbore Drill Bit
This specialized drill bit cuts the hole for the body of the screw or nail while also cutting a larger size indention for the head at the same time.
The counterbore drill bit is used particularly in furniture making so that screws with round heads or pan heads will be recessed into the wood and not visible
Hex Head Drill Bit
Also known as: Allen wrench bit
A hex head drill bit, or more commonly called an Allen wrench bit, is used to drive bolts and screws with a hexagonal opening in their heads. These bits take the conventional Allen wrench and add the power of a drill for added torque.
Left-Hand Drill Bit
Also known as: reverse-flute bit
Left-hand, or reverse-flute drill bits, are fluted in the opposite manner as traditional drill bits and are used to remove rounded-off screws or broken fasteners.
When rotated, left-handed bits have the tendency to snag seized fasteners, thereby spinning them free in the process.
Plug Cutter Bit
Plug cutter drill bits are a favorite of woodworkers and cabinet makers, as they allow one to easily conceal the head of most any screw.
Bits of this design are capable of cutting a hole with a countersunk base, while simultaneously carving out a tight fitting plug. This plug can be reinstalled to hide the otherwise obvious placement of a screw.
Acrylic Drill Bit
Also known as: plexiglass drill bit, plastic drill bit
Acrylic Drill Bits are specially designed to carve through plastic materials, such as Plexiglass, Lucite, and Perspex acrylic, without causing incidental damage.
Bits of this style typically feature tips that are orientated at a 90-degree angle. This prevents potentially harmful “grabbing” from taking place, which itself can lead to the onset of chips and cracks.
However, acrylic bits are seldom effective when used on other surfaces, such as wood or metal.
Self-Feed Drill Bit
A self feed drill bit is designed to bore through wood, and features a centrally-located pilot screw. As drilling commences, this screw pulls the bit deeper into the surface that is to be drilled.
A secondary row of large serrated teeth then chews away at the wooden surface, creating a clean hole of the correct diameter.
Installer Drill Bit
Installer drill bits are elongated in construction and feature an opening through which wire can be fed. Bits of this design can be used to bore through wood and plaster, but are also capable of drilling through the masonry of varying thicknesses.
Once through a wall, a wire can be fed into the bit, and withdrawn upon its removal, thereby simplifying wiring jobs that could otherwise prove quite difficult.
3-Wing Drill Bit
3-wing bits are excellent for drilling fiberglass. They are commonly used in the boat and RV industry for the installation of knobs, locks, etc. These bits are carbide tipped and available in multiple diameters.
Spot Weld Drill Bit
As their name would suggest, spot weld drill bits are specifically designed to bore out spot welds, allowing easy removal of panels and other bound surfaces.
Bits of this construction are constructed of cobalt or high-speed steel, and feature a pilot bit centered within a separate cutting flange. Spot weld drill bits tend to be a favorite of those within the autobody and metal fabrication fields.
Mortising bits consist of two individual parts, which include a hollow chisel and auger-style bit. A bit of this design is used to carve out square mortises, in the most simplified manner possible.
While the auger-style bit carves away expanses of material, the chiseled outer flange squares up the cut itself, leaving behind a clean mortise free of unsightly defects.
It is worth noting that mortising bits are designed to be used with a drill press, as pressure is required to facilitate the bit’s chiseling action.
Annular Cutter Bit
An annular cutter bit operates in much the same way with metal, as a hole saw bit does with wood. Bits of this type are capable of cutting sizable holes, without any need for piloting or predrilling.
Annular cutter bits generally operate by “sawing”, rather than by drilling, as one would tend to imagine. In turn, a clean, burr-free hole can be easily achieved.
Rivet Drill Bit
Rivet drill bits feature flutes on both ends, allowing you to obtain twice as much work out of a single bit. These bits are designed for drilling shallow holes through thin material, yet are unsuitable for heavier use.
Firewood Drill Bit
Also known as: wood splitting drill bit
Wood splitting drill bits are conical shaped bits used to aid in splitting wood. These bits usually come in sets of three with different shanks that fit various types of drills.
Drill & Saw Bit
A drill and saw bit set is an excellent addition to any garage. Drill bit sets generally include sizes from 1/16 inch to 1/2 inch, which will work for many typical jobs around the house and shop.
Sets of this type come in both metric and standard configurations. Larger bits can also be purchased at a later date for additional versatility.
Friction Drill Bit
Most friction drill bits are conical in nature and are composed of heat tolerant materials, such as cement carbide. Bits of this design rely solely upon friction, rather than cutting, to carve out a hole of the desired diameter.
Friction bits are placed directly against a work surface and rotated until a sufficient amount of material has been eroded away.
Drill Bit Materials
Carbon steel bits are available in both soft low carbon and high carbon steel, each having its own purpose. Low carbon steel bits are primarily used to cut soft woods and plastics. They are less expensive than their high carbon counterparts, and sharpening can extend their lifespan.
High carbon steel bits require less maintenance than soft carbon steel bits and hold their edge longer. They are tempered for both wood and metal cutting and are the preference for extremely hard woods.
High-Speed Steel (HSS)
High-Speed Steel, more commonly known as HSS, has high end hardness and improved wear resistance, making it the preferred material for drill bits.
High-speed drilling causes extensive friction, yet HSS bits are designed to operate at these high speeds, especially in conjunction with harder materials. High-Speed Steel bits are also commonly coated to reduce friction, and prevent premature wear.
Cobalt high speed steel bits have a higher red hardness than standard HSS bits. This hardness allows these bits to be used for drilling such materials as stainless steel, titanium, or cast iron.
They also exhibit superior abrasion resistance and are often utilized at higher cutting speeds.
Black oxide coating is a heat treatment process that is applied to HSS, which reduces friction while increasing the life of a drill bit by 50% or better over that of a standard HSS drill bit. Corrosion and rust resistance is added to the standard HSS bits by heating them to 950 degrees Fahrenheit.
Black oxide coated bits can be used for carbon and alloy steels, as well as wood, PVC, drywall, copper, and plastics.
Bronze oxide is commonly used to identify cobalt steel or in conjunction with black oxide for the identification of high grade steel. A bronze oxide coated bit has increased tempering, and is known for helping with lubricity during drilling.
Titanium, in the form of titanium nitride, is applied to HSS drill bits to give them high levels of hardness and corrosion resistance. By adding titanium nitride to a bit, friction is reduced between the bit and the material it comes in contact with, thus reducing heat and bit wear.
Titanium coated drill bits last up to 6 times longer than standard HSS bits and are used to drill through the toughest of materials.
Carbide-tipped drill bits are very hard and hold an edge longer than other types of bits. Carbide bits dissipate heat and are frequently used for drilling fiberglass and nonferrous heavy metals.
However, they tend to be brittle, and improper use may cause the bit to be broken
As their name would suggest, bi-metal drill bits are constructed of two or more types of metal. This makes it possible for a bit to feature an ultra-hardened tip, while also being able to possess a certain amount of flex to prevent breakage.
A number of steel bits come embedded with diamond dust, which allows them to easily cut through glass, ceramic, and stone. Bits of this configuration come in both hollow-core and solid state form, for added versatility.
However, it is worth noting that diamond drill bits are not intended for use on ferrous metals.
Alloy drill bits are constructed by mixing both metallic and non-metallic elements, which produces a robust blank that is quite hearty in nature.
Bits of this composition also tend to be extremely corrosion-resistant, making them a favorite of those working in the trades.