Types of Drill Bits
A drill is one of the handiest additions to the home tool box and is essential in just about any project, whether it's a quick decor DIY, a major room upgrade or building addition. But a good drill is useless without the correct drill bits for the job. This handy guide helps you make sense of the different options in drill bits and ensures you will buy the right single bit or drill bit set to get your project off the ground.
Drill bit sizes refer to their diameter. For most home projects, a drill bit set that ranges from 1/16-inch to ¼-inch drill bits will be a good start.
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, whereas 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 ¼-inch impact drivers and can be quickly changed. SDS (slotted drive system) shanks are used for concrete drill 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.
Choosing the correct drill bit size is a challenge for a new DIY-er, but there is information available to make it easier. Drill bits are sometimes sold with a pilot hole chart, a diagram used as a guideline to see how big the hole you’ll create will be. In general, when working with soft wood, choose a drill bit 1/64-inch smaller than the hole size you’ll need. For other materials, just select the same-size drill bit as the hole you’ll need.
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 abrasion, making them better for drilling into hard metals than black oxide- or titanium-coated drill bits.
- Carbide-tipped drill bits stay very sharp over long periods of use and are used mainly for concrete, tile and masonry.
Tip: Always follow the manufacturer's use and safety recommendations for drill bits and accessories. Make sure the drill bit is compatible with the specific drill you are using, even if they are the same brand.
- Light metal, wood, plastic, metal, ceramic, masonry
- General-purpose rotary drilling; most common drill bits for home use
- W-shaped centered point; produces a clean exit hole
- Screw-tip helps draw the drill; requires less pressure
- Bores holes with a large diameter
- Creates clean holes with a flat base; works better in a drill press than handheld drill
- Drills pilot holes and more to the right depth
- Creates a recess to countersink flush the head of fasteners
- Creates wood plugs that are used to conceal countersunk fasteners
- Metal, wood
- Allows drilling holes of multiple sizes with same drill bit; can be used to clean away waste material in holes
- Carbide-tipped bit reduces chips and cracks when drilling various types of tile
- Glass, ceramic
- Designed to drill holes in glass and ceramic; use with rotary drill only at slow speeds
- Concrete, brick, masonry
- Best used with a hammer drill; some models are designed for use with a rotary drill but they are slightly less effective
- Wood, metal, tile, masonry
- Attached to a shank to connect to drill; drills large cut-out holes, often used to fit piping
- Installer bits are designed for installing wiring. The drill bit has a hole in the side used for feeding wiring through the drilled hole.
- Self-centering drill bit ensures that the drill hole is accurately centered each time the drill is applied. Useful for pre-drilling holes for screw-mounted hardware
- Drill saw bits are used for cutting irregular holes in metal or wood. Best for small jobs; can’t replace a jigsaw.
- Pocket hole bits, when used with the proper jig, let you drill angled holes for screws. Best used for making wood joints.
- Scaling chisels are used for scaling and chiseling masonry. For use in hammer drills.
- Right-angle attachments give you access in tight spaces where the drill might not fit.
- Drill bit extensions give your drill a longer reach.
- Screw extractors let you remove stripped or damaged screws. Works with a reversible drill/driver.
- Depth stops let you set the depth to which you drill.
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 home drill bit sharpener can be a good investment to keep your drill bits in top shape. More experienced DIY-ers 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 tool set. 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.
Basic 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.
- 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. 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.