Knowing the different types of drill bits can help you choose the right tool for the job
In its simplest form, a drill is a tool that uses a rotary or cutting motion to make holes. This is a very open definition that includes everything from dental drills to tunnel boring machines. We'll focus on the types of drills we commonly use around construction and homes.
Before we dive in, though, let's get straight to a few technical definitions. A drill uses a drill to make holes. Drivers use screwdrivers to tighten screws, bolts and other fasteners. These two types of applications are what most people think of when they think about drills. So for our purposes we'll group them together.
Drill Driver – One of the most common types of drills
Both corded and cordless drills have a chuck that opens and closes slightly. Regardless of voltage, battery size or brand, these tools simply turn one clockwise and counterclockwise. Some cordless drills and drivers are also equipped with a drill clutch, which allows you to mechanically set the amount of power it transmits when driving a screw.
When to Use a Cordless Drill
Use a drill driver for basic drilling in plastic, wood, and metal. The size of the hole you are drilling determines how powerful a drill you need. The manual includes specs telling you what sizes it can handle. You can also glean some information from the size of the chuck. The 3/8" chuck does not support the larger 1/2" drills.
Cordless drills are also great for driving fasteners in plastic, wood, metal, concrete, and just about any other material, although some may require you to drill a pilot hole first.
impact drill
The basic design of a hammer drill or hammer drill driver is the same as that of a power drill. It just adds a hammer mechanism that vibrates the bit back and forth to cut away the concrete. This happens when the motor spins the bit. Most hammer drills let you choose hammer drill mode, drill only mode, or drive with a clutch. In other words, you can disable the hammer mechanism and use it like any other power drill.
When to Use a Hammer Drill
A rotary hammer is the all-purpose tool of the drill world. Use it to drill and drive in plastic, wood, metal and concrete/masonry. Note that for concrete drilling, most hammer drills are rated up to 1/4 in. You may also need a vacuum cleaner and a hood to prevent inhaling silica dust and avoid silicosis.
Rotary hammer (combination hammer)
Electric hammer, or combined hammer (combihammer), is the big brother of electric hammer. These types of concrete drill rigs range in size from a little larger than a hammer drill to much larger. They use a stronger hammering/cutting mechanism to deliver more power than impact drills.
These tools usually have at least two modes: cutting and rotary hammering. Some only give you the swivel option, but few pros use it, even though it's capable of drilling through wood and metal.
Chipping does what it sounds like—it uses a chipping drill to strike like a mini jackhammer to remove it. Rotary hammering is the mode you use to drill holes in concrete, asphalt, brick, stone, or other masonry.
When to Use a Rotary Hammer
Use a rotary hammer when drilling or breaking concrete, asphalt, stone, brick, or masonry. The largest of these tools supports drilling up to 2 inches.
Impact Drivers (Hear us out!)
While it's not a true drill type, the impact driver made our list mainly because of the sheer number of hex fittings available. The hex chuck on these tools is called an impact driver and supports compatible spade bits, auger bits, and more. Impact drivers do not use a forward cutting mechanism, but a rotating hammer and anvil mechanism. As the chuck turns, the hammer strikes the anvil violently, causing it to generate much greater rotational force than a standard drill bit.
As we mentioned above, many drills now come with "impact ready" 1/4" hex shanks. This allows you to use an impact driver to drill holes in metal, plastic or wood. It's not as smooth as a drill, but it sure gets the job done.
When to Use an Impact Driver
Impact drivers are the construction world's screwdriver champions, capable of turning screws faster than standard drill drivers. While you can use it to drill holes through a suitable drill, many professionals use it with a drill so they don't have to change bits while they're working. When it comes to choosing a drill or an impact driver – use both. It can really save you some time.
Core drill
Core drills are one of the rarer types of drill bits. It's basically a large motor, sometimes attached to a frame, that holds it steady while drilling. It turns a coring bit — a cylindrical bit that creates a coring instead of grinding away the entire hole. All it does is spin the drill. No hammering, chipping or driving applications.
When to Use a Core Drill
Nothing can do the job of a core drill. Use a core drill when you need to drill a large hole in concrete—even up to several feet in diameter! These specialized tools move slowly, but sometimes the work just takes time.
Earth Auger
A ground auger or earth auger uses AC or gas power to turn its powerful motor. An auger uses an aggressive, wide bit that tears through the ground and removes dirt faster and easier than a post hole digger or shovel. Recently, we've seen cordless augers like the Makita earth auger and the Ryobi 40V brushless auger appear. These bring wireless convenience and battery power to tools that were previously limited to gas.
When to Use an Earth Auger
Augers are used as large ground moving machines. These types of drills will make your life easier when you need to make a hole in the ground (or even ice). Use it to set up all types of posts, as well as when cutting holes for ice fishing.
Note that while earth and ice drills look and function similar, you do see some differences. For example, ice drills typically spin at a high RPM. These tools also don't weigh as much as a ground drill, and the sharp blades don't tangle up as easily, so they rarely include clutches. Finally, the less steep blade pitch and sharper blades of the ice drill make it better for digging through ice than navigating through rock and mud.
cordless screwdriver
While not technically a power drill, a power screwdriver works in the same way as a power drill. These typically feature an inline design rather than a pistol grip, and are less powerful than standard cordless drills. They rotate the chuck clockwise or counterclockwise and are mainly used to drive small screws. While they are capable of drilling small holes, they are not the best tool for the job.
When to Use a Cordless Screwdriver
Power screwdrivers are best for small and/or delicate fasteners that don't require the torque of a standard power drill. They're great for working in distribution boxes, setting switch panels, and anywhere else you can use a handheld screwdriver.
Drywall screwdriver (drywall screw gun)
A drywall screwdriver isn't technically a drill either, but a pure driving/fastening tool. These are usually spun at a higher RPM to fasten the screws. While sharing the basic design of a pistol grip drill, these sometimes have a grip and a lock directly behind the motor, allowing you to work faster. Professional models usually have organized magazines that allow you to screw on automatically as you go. This greatly speeds up the work.
When to Use a Drywall Screwdriver
As the name suggests, a drywall screw gun helps you install drywall panels quickly. Models that can handle longer screws also make deck building a breeze.
wrap it up
Are we missing other types of drills? No matter what job or project you have laid out, their roots can be traced back to when humans first learned how to spin a sharp stone back and forth to punch a hole in another object. When you look back even 100 years, you can see how much the drill has improved!