There are several varieties of drill bits available to perform a number of different jobs. The types of drill bits will vary by the angles and shapes of the drill point, spirals for the shaft and length. Be mindful of the drill bit you choose for a home project, for it may be better suited for another purpose. Not only will choosing the right drill bit make your job easier, but the bit itself will last much longer when used only for its intended materials.
Drill Bits Shape
The average hardware store has a vast selection of drill bits. The most common drill bit has a twisted shaft, a point angled at around 118 degrees and drills into most household materials. It’s popular with DIY homeowners because it can be used for so many projects; however, this one-size-fits-all drill bit is not the best choice for every project. Drill bits perform best on the materials for which they’re intended. For example, plastics drill better when the drill bit has a point angle of 90 degrees, but steel drills better with a tip angle around 130. Often, you have to drill a starter hole to drill steel or another very hard material accurately.
The edge or angle of a drill bit point is what determines the kind of material it can penetrate.
For example:
Flatter points – best for drilling into harder materials
Steeper points – best for drilling into softer materials
Split point bit tips – best for efficiency and accuracy when drilling to prevent a bit from drifting from the drilling point area
Drill Bits Material
Not only do drill bits vary by shape, but the material of the drill bit itself can be different. Soft, low-carbon steel is a cost-efficient and common drill bit material. It’s good for wood, but wears quickly, and should not be used on metals. Bits made from high-speed steel (HSS) can drill metal, hardwood, PVC and most other materials. They have good heat resistance and can be coated with black oxide to reduce corrosion and wear. Drill bits with cobalt heat up quickly but are tough enough to drill through steel and other metals. To drill tougher materials like masonry, the HSS drill tips should be coated with titanium carbon nitride, carbide or even diamond powder. Masonry drill bits are often Slotted Drive System (SDS) bits designed to work in hammer drills.
The most common drill bit materials include:
Steel Bits are less costly and are typically used with softer wood materials. They wear and dull quickly and can sometimes break, particularly when they are used with harder wood materials.
High-Speed Steel (HSS) Bits are harder, remain sharper for a longer period of time and can drill soft metals, polyvinyl chloride (PVC), wood and fiberglass.
Black Oxide-Coated HSS Drill Bits possess longevity in contrast to other high-speed bits because of their coated finish and their resistance to wear. They are considerably more durable, plus they work well with a combination of materials such as metal, hardwoods, softwoods, fiberglass and poly-vinyl chloride (PVC).
Titanium Coated Bits are more expensive than high-speed steel bits, but they are also longer-lasting, harder and retain their sharpness. They are best utilized with metal, wood, fiberglass and poly-vinyl chloride (PVC).
Cobalt Drill Bits are exceptionally hard and quickly dispel heat. They are used with stronger metals like stainless steel and for aluminum penetration.
Carbide-Tipped Drill Bits are costly, but they retain their sharpness more than any other bit.
Manufacturers typically make several varieties of drill bits for different jobs and materials. Your project may be affected if you’re not careful of the bit you’re choosing, so take a look at our breakdown of the 10 most common types of drill bits.
Drill Bit Size
A bit’s size matches the width or thickness of its structure. Particular projects will require a definite or precise size bit. There are drill bit sets or packs that usually contain bit sizes that range from 1/16 of an inch to 1/4 of an inch, which are common sizes for home and shop projects. Other sizes of use would include 1/2 of an inch, 7/16 of an inch, 5/16 of an inch and 3/8 of an inch.
Drill Bit Types
Auger Drill Bit
Designed for wood
Shaft has a small threaded point like a miniature drill on the tip
Large flutes to remove material as it drills
Brad Point Bit
Used for wood
Has a point in the middle of the drill tip and sharp edges
Large flutes to remove material as it drills
Center point increases accuracy of drill holes
Also called a lip and spur drill bit or a dowelling bit
Countersink Bit
Most commonly used for wood
Has a bit that changes sizes from narrow to wide
Makes holes where screw heads can sit flush in the hole
Used to drill countersink, counterbore and pilot holes
Also called a screw pilot bit
Glass Bit
Used for glass and tile
Has a carbide tip shaped like an arrowhead
Successively larger bits used to make the hole
Masonry Drill Bit
Made to drill masonry
Tip is usually coated with titanium, carbide or another very hard material
Shaft spirals more than a metal drill bit and comes to a point
Some are designed for a standard rotary drill, but often used with a hammer drill
Metal Drill Bit
Used for metal
Can be used on other materials, but will wear faster
Usually black and coated with titanium or another harder material
Twists to a point from the shaft
Screwdriver/Nut Driver Bits
Used to drive screws/nuts into a variety of materials
Screwdriver bit has a bit holder with a tip like a flat-head, phillips or pozidriv screwdriver
A nut driver bit has a hollow tip like a wrench
Often used with a reversible drill to remove existing screws and nuts
Twist Bit
Used for wood, plastic, light metal and other softer materials
Shaft twists up to a point
Most common drill bit type in the average hardware store
Unibit
used on thin woods, acrylics and metals
Conical shape with steps increasing in size
Can make multiple hole sizes in thinner materials
Often used to deburr existing holes
Wood Spade Bit
Designed for wood
Wide flat tip like an oar with a point in the center
Sharp center point more accurately positions the hole
Also called a paddle bit
Securing a Drill Bit – Shafts/Chucks
After selecting the right drill bit for your specific project, you will need to ensure the drill bit is secured through a chuck which tightens around the shaft/shank of the drill bit to keep and secure the bit while the actual drill is in use. Most household drills have 3/8 of an inch chucks, while drills for heavier work have 1/2 to 5/8 inch chuck sizes. Larger drill bits may have shafts/shanks that are smaller so they can accommodate smaller chucks.
Round Shank/Shaft – provides for centering a bit in the chuck
Hex Shank/Shaft – flat surfaced shank that provides for a tighter grip and greater turning force (torque). This type of shank works with quick-change chucks that are standard with cordless drills. This quick-change provides for placing and removing a shaft without dealing with the tightening and loosening of a chuck.
Slotted Drive System (SDS) Shank/Shaft – provides for use on a hammer drill. The bit is held steady while it moves back and forth with the movement of the drill. Flat areas and actual slots on the shank/shaft give the chuck the ability to hold the bit.
Doug Ashy is your source for high-quality, affordable tools and materials, and our experts are ready to answer any questions you may have! Whether you’re looking to purchase drill bits or learn more about what type of drill bit is best for your next home improvement project, check out of our complete selection of drill bits in our online catalog or visit one of our locations to speak with our team of knowledgeable staff.