What are Drill Bits?
Drill bits are designed to drill holes in a variety of different common materials. These include different types of wood, metal, plastic, ceramic tile, porcelain, and concrete. Drill bits made for steel, aluminum, copper, cast iron, sheet metal, fiberglass, brick, vinyl flooring, and more are also available.
Sized for their diameter, drill bits are constructed in a range of styles to help with specific tasks. Not sure which drill bit you need or what you need in your toolbox? Keep reading for a rundown of the different types of drill bits you’re likely to come across.
Materials and Finishes
Drill bits are often classified by the materials from which they are manufactured and the coatings applied to them.
- High-Speed Steel (HSS) drill bits are used for drilling wood, light metals, fiberglass and PVC.
- Black oxide-coated drill bits are more durable than standard HSS bits and the coating helps the drill bit resist rust. These are best for hardwood, softwood, PVC, fiberglass and steel.
- Titanium-coated drill bits have reduced friction, require less effort and last longer than black oxide-coated bits. These are best for hardwood, softwood, PVC, fiberglass and steel.
- Cobalt drill bits are used for drilling hard metal and steel. They dissipate heat quickly and are highly resistant to abrasions, making them better for drilling into hard metals than black oxide- or titanium-coated drill bits. When considering a cobalt drill bit vs titanium, cobalt bits are usually the best drill bits for stainless steel.
- Carbide-tipped drill bits stay very sharp over long periods of use and are used mainly for concrete, tile and masonry. These are often the best masonry drill bits for your project.
- Bi-metal drill bits are useful for a range of materials like light metal, wood and PVC; bi-metal drill bits cut fast and smooth with greatly reduced vibrations.
- Diamond drill bits are ideal for cutting into glass, sea glass, fused glass, rocks and minerals.
- Alloy steel drill bits are typically used in machine shops for cutting sheet metal of varying thicknesses. These are often the best drill bits for metal if you’re working exclusively with thin materials.
Coatings used on drill bits:
Black Oxide: The most economical coating. Black oxide adds corrosion protection, increases tempering and stress relieving of the bit, reduces galling and chip welding, and aids in retaining drilling lubricants. Black oxide is suitable for drilling iron and steel but is not recommended for drilling aluminum, magnesium, or similar materials.
Bronze Oxide: Bronze oxide increases tempering and stress relieving of the bit and is generally used alone to visually identify cobalt steel or with black oxide to identify better grades of high-speed steel.
Titanium Nitride (Tin): A more expensive coating that increases the hardness of the bit and provides a thermal barrier resulting in increased production rates and longer tool life in harder materials. Tin also provides the same benefits as black and bronze oxide. Tin-coated bits are suitable for drilling iron and steel as well as aluminum, magnesium, etc.
Drill Bit Construction
When it comes to drills, there are two easily identifiable parts you need to know about – the shank and the chuck. Here’s a little information to help you understand more about how drills and drill bits work:
The shank is the end of the drill bit that fits into the drill and is secured by the chuck. A round shank helps to center a bit in the chuck more accurately. The flat surfaces on a hex shank allow the chuck to grip the drill bit more securely.
Quarter-inch hex shank bits are intended to be used on 1/4-inch impact drivers and can be quickly changed. SDS (slotted drive system) shanks are used for concrete drills and demolition bits and work specifically with SDS-Plus and SDS-Max rotary hammer drills.
The chuck is the part of the drill that attaches the drill bit. Most power drills for home use have a 3/8-inch or 1/2-inch chuck. Larger chucks come in 5/8-inch and 3/4-inch sizes but are usually fitted on heavy-duty and industrial power drills and drill presses.
Different Types of Drill Bits & Their Uses
1. Twist Drill Bit
Also known as high-speed bits, they resemble corkscrews and are some of the most popular bits. They are typically used to drill small holes into wood and walls. Their unique design allows them to channel dust from the hole as they work.
- Twist drill bits can be used on light metal, wood, plastic, metal, ceramic and masonry.
- Useful for home repairs, maintenance and building projects with metal, wood or ceramics.
- General-purpose rotary drilling; most common drill bits for home use.
2. Brad Point Drill Bit
Brad-point bits come in handy when you need to make clean and precise holes. They come with rubber stoppers to allow you to set a particular depth. Their precision makes them a popular bit among woodworkers.
- Brad point drill bits can be used on wood.
- Useful for furniture making, cabinetry and general woodworking.
- W-shaped centered point; produces a clean exit hole.
- Often the best drill bit for wood DIY projects.
3. Masonry Drill Bit
These are what you use when looking to create holes in bricks, stones, or concrete. Due to the tough nature of those materials, masonry bits wear out quickly, meaning that you will need to replace them frequently.
- Masonry drill bits can be used with concrete, brick or masonry.
- Useful for home building and repairs.
- Best used with a hammer drill; some models are designed for use with a rotary drill but they are slightly less effective.
4. Rivet Drill Bit
Rivet bits feature a special design that allows them to drill rivets into thin sheets of metal.
5. Spade Drill Bit
Spade bits have a spade-shaped tip that allows them to bore into softwoods. They are typically used to create holes for running cables.
- Spade drill bits can be used on wood.
- Useful for drilling holes in wall studs for framing, electrical, plumbing and fine woodworking projects.
- Bores holes with a large diameter.
6. Installer Drill Bit
Professionals use installer bits to bore holes for installing wiring for entertainment or security systems. The tip of the bit has a tiny hole where you insert the wire you are looking to pass through the material. Installer bits are incredibly long, reaching lengths of up to 18 inches to facilitate their work.
- Installer bits can be used with wood.
- Useful for woodworking and cabinetry projects.
- Creates wood plugs that are used to conceal countersunk fasteners.
7. Step Drill Bit
Named after their tip that resembles a series of pyramid-shaped steps, these bits are what professionals use to drill into sheet metal. Their stepped design allows you to create holes with varying diameters. Step bits are renowned for their versatility.
- Step drill bits can be used with metal and wood.
- Useful for drilling pilot holes in woodworking and sheet metal-based projects.
- Allows drilling holes of multiple sizes with same drill bit; can be used to clean away waste material in holes.
8. Auger Drill Bit
These are the bits to use when looking to drill into thick and dry wood. Thanks to their innovative design, you do not have to apply a lot of pressure when drilling into tough materials. Auger bits have a screw tip that creates the initial hole for the rest of the bit to fall. As a result, holes by auger bits are incredibly clean and precise.
- Auger drill bits can be used on wood.
- Useful for large woodworking and building projects.
- Screw-tip helps draw the drill; requires less pressure.
9. Self-Feed Drill Bit
Like auger bits, self-feed bits also feature a screw tip for positioning the bit. They create clean, precise holes, as well. However, since they do not channel the dust away from the hole as they work, you must halt the operation periodically to clear the dust away.
10. Forstner Drill Bit
These are what you use when looking to bore smooth and clean holes into the woods. This bit also comes with a pointed tip to allow for easy positioning of the bit.
- Forstner drill bits can be used on wood.
- Useful for woodworking and building projects.
- Creates clean holes with a flat base; works better in a drill press than a handheld drill.
11. Hole Saw Drill Bit
Hole saws are bits that allow you to drill large holes such as those for door hardware installation.
- Hole saws can be used with wood, metal, tile and masonry.
- Useful as a multi-purpose bit for building, renovation and repairs.
- Attached to a shank to connect to drill; drills large cut-out holes, often used to fit piping.
12.Countersink Drill Bit
These are versatile bits that allow you to drill holes such as counterbore, countersink, and pilot holes into wood.
- Countersink drill bits can be used on wood.
- Useful for general woodworking and cabinetry.
- Drills pilot holes and more to the right depth.
- Creates a recess to countersink flush the head of fasteners.
13. Plug Cutter
Plug cutters are helpful in professional projects, as they drill holes into the wood while cutting the wood plugs you require to hide recessed fasteners.
14. Tile drill bits
These bits come with carbide tips to allow you to bore holes into tiles without creating chips or cracks in the tile. Different tile bits are designed for different types of tiles. Therefore, ensure that you check its package to confirm that it can drill into your tiles.
- Tile drill bits can be used with ceramic and porcelain tile.
- Useful for flooring, backsplash and tile wall installations or renovations.
- Carbide-tipped bit reduces chips and cracks when drilling various types of tile.
15. Adjustable Wood Drill bits
As their name implies, these bits can be adjusted to create holes of varying sizes, thus eliminating the need for purchasing bits of different sizes.
16. Annular Cutter
These bits have a special design that allows them to drill a hole into a material with the purpose of extracting its core.
Used to drill larger thru-holes in metal (7/16″ and up), these bits require a special machine. Similar to a hole saw, annular cutter bits cut the outer diameter of the hole and leave a solid center slug.
This creates a much more efficient drilling process with burr-free holes in tubing, sheet metal, and iron bar stock. Annular cutter bits on our site are made from Cobalt High-Speed Steel.
17. Bits for Metal
Metal bits are built for heavy-duty work, such as cutting steel. They are one of the costlier bits out there.
18. Glass and Tile Drill bits
These are special types of bits that can drill through plastic, tiles, glass, marble, and brick. They can also withstand high temperatures.
- Glass drill bits can be used with non-tempered glass and ceramic.
- Useful for DIY home renovations and repairs.
- Designed to drill holes in glass and ceramic; use with rotary drill only at slow speeds.
19. Hammer Drill bits
You use a hammer bit to create precise holes into concrete slabs when looking to determine the amount of humidity in a concrete slab.
20. Bullet Point Drill bits
These are special kinds of bits that can drill through wood, plastic, and metal. They create remarkably clean holes.
Drill Bit Maintenance
Proper drill bit maintenance is not much different from maintenance for most tools, and it helps prolong the life of your drill bits and keeps them ready for the next job. Caring for your drill bits can also be a matter of safety; dull or damaged drill bits can create problems both in the work and for the worker.
Drill bits are cutting tools. If you do a lot of home projects or heavy-duty construction work, periodically sharpening your drill bits will be necessary. Dull drill bits can increase time and effort needed to complete work and possibly damage the materials you’re working on, and may even cause injury.
A sharpening tool can be a good investment to keep your drill bits in top shape. More experienced DIYers can accomplish the task with a good set of grinding tools.
Most drill bit sets are sold in a case with space to hold each bit in place. This keeps the drill bits from being nicked or scratched and also provides excellent organization. Each spot is marked for the bit’s size and type, making it easy to quickly find the right bit for the project you are completing.
If your set didn’t come with a case or you’ve been buying individual drill bits, add a storage box with dividers to your toolset. Don’t store more than two bits together and use a permanent marker to mark each space with the size and type of drill bit stored there.
Tips for Proper Drill and Drill Bit Maintenance:
- Let the drill bit cool off after you have finished your project.
- Wipe the drill and drill bit with a clean, dry towel or cleaning cloth.
- Use a clean, dry toothbrush to brush off any shavings or other debris that may cling to the tool.
- Apply machine oil lightly with a paper towel or microfiber cloth. Let it sit for a few minutes, then wipe up any excess oil with a new paper towel.
- Inspect drill bits for any extensive damage and remove damaged drill bits from the set so they can be replaced.
- Place drill bits back into their case and store in a cool, dry place.