Drill Bit: What It Is, Types, and How to Use It

A drill bit is the cutting piece that does the actual hole-making when you use a drill. It locks into the drill’s chuck (the clamping jaws), spins at speed, and cuts away material to create a hole of a specific diameter. Bits come in many sizes, shapes, and materials so you can match the bit to your project and the material you’re drilling.

How a Drill Bit Works

Most drill bits have spiral grooves called flutes. As the cutting tip advances, the flutes carry chips or dust out of the hole, keeping the cutting edges clear. The bit’s shank is the smooth end that the drill grips. When you squeeze the trigger, the drill rotates the bit; sometimes you also use percussion (hammer drill mode) to help a masonry bit break up brick or concrete.

Key parts you’ll hear about:
- Tip or point: The cutting edge that starts the hole.
- Flutes: Spirals that remove chips and debris.
- Shank: The end clamped in the chuck; can be round, hex, or SDS.

Common DIY Uses

Hanging shelves, TVs, and cabinets (pilot holes in wood, anchors in masonry)
Installing hardware (hinges, handles, brackets)
Running cables or plumbing (boring larger holes through studs)
Building furniture or decks (pilot holes and countersinks)
Working with metal projects (drilling steel, aluminum)
Tiling and bathroom work (careful holes in tile or glass with specialized bits)

Types of Drill Bits

For Wood

Twist (standard): General wood use; common and affordable.
Brad-point: Center spur helps start accurately with clean entry holes.
Spade (paddle): Fast, large holes (1/4"–1-1/2") in studs; rougher finish.
Auger: Deep, straight holes with screw tip; good for framing and outdoor lumber.
Forstner: Flat-bottom, clean holes; great for concealed hinges and dowels.

For Metal

HSS (High-Speed Steel): Everyday drilling in mild steel, aluminum, and plastics.
Cobalt (M35/M42): Handles hard metals and stainless steel; slower speed, use cutting oil.
Black oxide/TiN-coated: Surface treatments that reduce friction and heat.
Step bit (unibit): Cone-shaped; enlarges holes in sheet metal cleanly.

For Masonry

Carbide-tipped masonry: Use with hammer drill mode for brick, concrete block, and stone.
SDS-Plus / SDS-Max: Specialized shanks for rotary hammers; heavy-duty concrete work.

For Tile, Glass, and Ceramics

Spear-point (carbide): For soft tile and glass; low speed, light pressure, water for cooling.
Diamond-grit: For porcelain and hard tile; keep cool with water.

Hole-Making Accessories

Hole saws: Circular cutters for large holes (doorknobs, pipe penetrations); select wood, bi-metal, or diamond types depending on material.
Countersink bits: Create a tapered recess for screw heads.

Shanks and Chucks

Round shank: Fits standard keyed or keyless chucks on most drills.
1/4" Hex shank: Quick-change in impact drivers and some drills; handy for brad-point and step bits.
SDS-Plus / SDS-Max: Slotted shanks for rotary hammers; allow hammering action without slipping.

Match the shank to your tool. Impact drivers can spin hex-shank drill bits, but avoid hammer action with non-masonry bits.

Sizing, Materials, and Coatings

Sizes: Bits come in fractional (1/16"–1/2"), metric, letter, and number sizes. For most DIY, fractional and metric cover it.
Materials: HSS for general use, cobalt for tough metals, carbide tips for masonry, diamond grit for porcelain.
Coatings: Black oxide and titanium nitride (gold) reduce friction and corrosion but do not turn a poor-quality bit into a premium one.

How to Choose the Right Drill Bit

Identify the material: wood, metal, masonry, tile, or plastic.
Pick the type designed for that material (e.g., brad-point for precise wood holes, masonry for brick).
Match the size to your anchor, screw, or hardware. Use manufacturer charts for pilot hole sizes.
Check your tool: standard drill, hammer drill, or rotary hammer; choose compatible shank.
Quality matters: A few well-made bits in common sizes outperform a large cheap assortment.

Tips for Use

Start straight: Use a center punch on metal or a brad-point bit for wood to prevent wandering.
Speed control: Faster for wood, slower for metal and large bits. If you see smoke, slow down and reduce pressure.
Lubricate metal: A drop of cutting oil on steel and stainless keeps the bit cool and sharp longer.
Support the work: Clamp your piece and use a scrap backing board to reduce tear-out on the exit side.
Pilot holes: Pre-drill smaller holes for screws to prevent splitting and to make driving easier.
Clear chips: Pulse the trigger or back out briefly to evacuate debris, especially in deep holes.
Tile and glass: Tape the spot, start at a slight angle, no hammer mode, and keep the bit cool with water.
Masonry: Use hammer mode, steady pressure, and vacuum dust. For deep holes, periodically withdraw to clear debris.

Maintenance and Storage

Sharpening: Twist bits can be sharpened with a jig or at a bench grinder; brad-point, Forstner, and spade bits can be touched up carefully. If unsure, replace.
Rust prevention: Wipe with a lightly oiled rag after use, especially if stored in damp areas.
Keep organized: Store in labeled cases or racks so sizes are easy to find and edges stay protected.

Common Mistakes to Avoid

Using a wood bit on masonry or tile (it will dull quickly and may shatter tile).
Running too fast on metal, causing heat buildup and blue, burned tips.
Skipping pilot holes for large screws, leading to splits and stripped heads.
Forcing the drill; let the bit cut. Excess pressure bends bits and overheats edges.
Forgetting a backing board, which causes tear-out on plywood or laminates.
Using hammer mode on tile or metal; reserve hammering for masonry with the correct bit.

Related Terms

Chuck: The clamping jaws that hold the bit.
Pilot hole: A small hole drilled to guide screws or larger bits.
Countersink: A conical recess for screw heads.
Hole saw: A circular cutter for larger diameter holes.
Impact driver: A tool that delivers rotational impacts; use hex-shank drill bits when drilling light materials.
Rotary hammer: A heavier tool for concrete with SDS bits.

Practical Examples

Mounting a TV on brick: Use a carbide-tipped masonry bit with a hammer drill, matching the anchor size, and drill to the embed depth marked on the bit with tape.
Installing cabinet handles: Use a brad-point bit sized to the hardware screw for clean, accurately placed holes through finished doors.
Drilling stainless steel: Choose a cobalt bit, mark with a center punch, run at low speed with cutting oil, and apply steady pressure.
Running a 3/4" water line through studs: Use an auger or spade bit, drill centered in the stud, and add nail plates where required by code.
Cutting a doorknob hole: Use a bi-metal hole saw guided by the supplied pilot bit; clamp a backing board to reduce blowout on the exit side.