A drill is one of the best additions to the home toolbox and is essential in just about any project, whether it's a quick decor change, a major room upgrade or a big building addition. However, a good drill is useless without the correct drill bits for the job.
This guide helps you make sense of drill bits so you can choose the right single bit or drill bit set to get your project off the ground.
What are Drill Bits Used For?
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.
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.
Twist Drill Bit
- 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.
Brad and Pilot Point Bit
- 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.
Auger Drill Bit
- Auger drill bits can be used on wood.
- Useful for large woodworking and building projects.
- Screw-tip helps draw the drill; requires less pressure.
Spade Drill Bit
- 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.
Forstner Drill 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.
Countersink Drill Bit
- 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.
- Installer bits can be used with wood.
- Useful for woodworking and cabinetry projects.
- Creates wood plugs that are used to conceal countersunk fasteners.
Step Drill Bit
- 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.
Tile Drill Bit
- 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.
Glass Drill Bit
- 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.
Masonry Drill Bit
- 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.
- 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.
Screwdriver Drill Bit
- Screwdriver drill bits can be used with many materials depending on tip type.
- Useful for building projects, renovations and machine work.
- Used with handheld drills and impact drivers depending on type.
Coring Drill Bit
- Coring drill bits can be used with masonry, brick, wet concrete, concrete, concrete blocks and more depending on tip type.
- Useful for heavy-duty building projects.
- Often used with a rotary hammer and impact tools.
- Usually the best drill bit for concrete work.
Bit Holders and Extensions
- Bit holders and extensions can be used with many different bit types.
- Useful for extending your tool's reach for hard to access work.
- Used with handheld drills and impact tools.
Specialty Drill Bits & Accessories
- 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 drill attachments give you access in tight spaces where the drill might not fit.
- 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.
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.
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.
Drill Bit Drive Styles
Drill bits come in a range of drive styles, and different options can be useful depending on the work you're doing. Here are a few common types to know:
- Hex bits: Designed to work when an Allen key won't fit, hex bits are often used for furniture construction and disassembly.
- Square bits: Similar to hex bits, square bits are often used in commercially made products and furniture. They're often replaced by hex products in modern production.
- Torx bits: Shaped like a six-sided star, these are often used on vehicles and for some electronics.
- Phillips and slotted bits: A common type of screwdriver bit useful for basic at-home building and repair projects.
- Combination drill bits: A useful multi-purpose bit set that can help handle more building and repair tasks.
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 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.
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.
For most home projects, twist or brad point styles are usually the most useful types of drill bits. You can always add other sizes and specialty drill bits as you need them as well. Choosing the correct drill bit size may seem like a challenge at first, but it gets easier the more you use your drill.
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