Drill bits are the interchangeable cutting tools that turn any drill into a hole-making machine. Electricians, carpenters, and plumbers use them to run wiring, set pipes, and build joinery, while home DIYers reach for them to mount shelving, hang flat-screen TVs, and assemble furniture. The tip of each bit drives into wood, metal, masonry, tile, plastic, or glass, and the metal it is made from decides which surfaces it can handle. Before building out your collection, a broad power tool accessory selection guide that compares drill bits, driver bits, and spade bits helps you match a kit to the jobs you actually do.
How Drill Bits Work and What the Specs Mean
A drill bit is a rotary cutting tool held in the jaws of the drill chuck. The chuck grips the shank, and power from a battery or corded motor spins the bit clockwise to cut or counterclockwise to back it out of a hole. Manual hand drills cranked by hand do the same work at lower speeds. Rotation speed matters: small bits turn fast, while large diameters and masonry bits need slower turning with firm pressure.
Shank Styles and Chuck Compatibility
The shank is the part the chuck grips, and its shape decides which drills accept the bit. Round shanks fit the standard three-jaw chuck on most cordless drills. Hex shanks drop into quick-change chucks and impact drivers, where the flat faces let the chuck bite harder without slipping. SDS shanks with keyed grooves are built for rotary hammers and slide in and out without a chuck key.
Bit Materials: High-Speed Steel, Cobalt, Carbide, and Diamond
Most general-purpose bits are high-speed steel (HSS), which holds an edge through wood, plastic, and soft metal. Cobalt alloy bits survive the heat of stainless steel. Carbide-tipped bits shrug off the abrasion of brick and concrete, and diamond-grit bits grind through the hardest tile and glass. When a job calls for porcelain tile, diamond-tipped drill bits are the standard answer because ordinary steel skates across the glazed surface without cutting.
| Bit type | Best materials | Typical use | Speed tip |
|---|---|---|---|
| Twist (HSS) | Wood, plastic, soft metal | General-purpose holes | High RPM at small diameters |
| Brad point | Wood, plywood | Clean, precise entry holes | Medium speed, light pressure |
| Spade | Wood, framing lumber | Fast rough holes | Slow speed to limit splintering |
| Masonry | Brick, block, concrete | Anchor and fastener holes | Slow speed, steady pressure |
| Cobalt | Stainless and hard steel | Metal fabrication | Low speed with cutting oil |
| Diamond | Porcelain, tile, glass | Tile and glass holes | Slow speed, water cooling |
Keep a copy of this lineup near the toolbox, because reaching for the right family the first time saves both time and broken bits.
Twist Bits and Multi-Purpose Designs
The twist bit is the default for most drilling. Flutes spiral up the body to lift chips out of the hole while the cutting lips at the tip shear material away. Twist bits in HSS cover the majority of household tasks, from pilot holes in studs to hardware installation in cabinets.
Reading Bit Geometry
Point angle changes how a bit starts. A 118-degree point suits general work, while a 135-degree split point walks less on smooth metal and starts faster without a center punch. Flute depth and web thickness also affect chip clearance, so a bit that jams in deep holes often needs a more open flute.
Design Improvements in Modern Bits
Manufacturers keep revising geometry to cut faster and last longer. Screwdriver bit and drill bit design refreshes show how new flute shapes, tip grinds, and coatings get tested before release. Titanium nitride and black-oxide coatings reduce friction and resist corrosion, and impact-ready driver bits add torsion zones that twist under load instead of snapping.
Masonry and Concrete Bits
Masonry bits look like beefed-up twist bits with a flat carbide tip brazed to the cutting end. Instead of shearing material, the tip pounds and grinds brick, block, and concrete into dust.
Carbide-Tipped Masonry Bits
The carbide tip does the heavy work while the steel body carries dust out through its flutes. Standard masonry bits work with any drill in hammer mode for occasional anchor holes, but they dull quickly in hard concrete and when they hit rebar.
SDS Shanks and Rotary Hammers
Rotary hammers with SDS chucks deliver the impact energy that heavy concrete demands. The shank slides into the chuck and locks, and the hammer action breaks material while the bit rotates.
SDS-Plus Versus SDS-Max
SDS-Plus shanks measure 10 mm and fit most job-site rotary hammers up to about 1-1/8 inch bits. SDS-Max shanks are 18 mm and handle larger bits and demolition work, but the tools are heavier and cost more. Choose SDS-Plus for residential anchor drilling and SDS-Max for heavy commercial work.
Technique decides how long the bit survives. Start with a pilot hole at low speed, keep the bit perpendicular to the surface, and let the hammer do the work instead of leaning on the drill. A walkthrough of drilling into concrete and mastering masonry techniques covers anchor selection, dust control, and depth marking so the finished hole is straight and sized for the fastener.
Wood Drill Bits for Carpentry and Framing
Wood bits are engineered around clean entry and fast chip removal. The right bit keeps tear-out off the face of trim and stops binding in deep stud bays.
Brad Point and Spur Bits
A brad point bit has a sharp center spur that locates the hole exactly, plus outer spurs that score the wood fibers before the cutting lips arrive, so holes come out clean with little splintering. Cabinetmakers reach for them when the exit side has to look as good as the entry.
Spade, Auger, and Forstner Bits
Spade bits are flat paddles that bore fast rough holes through studs and framing. Auger bits pull themselves through thick stock with a screw tip and deep flutes that clear long shavings. Forstner bits cut flat-bottomed holes for hinges and hardware and can start at an angle on rounded surfaces.
Choosing Diameter and Length
Match the diameter to the fastener: a 3/32-inch pilot suits a #8 wood screw, while 1/4-inch holes take most plastic anchors. Length should clear the material thickness plus room for the chuck, and extra-long bits reach through double-wall framing.
- Mark the hole center and dimple it with an awl or center punch.
- Start the drill at low speed until the tip bites.
- Drill a pilot hole before opening it to the final diameter.
- Back the bit out often to clear shavings and avoid burning.
- Clamp a scrap board behind the workpiece to stop exit tear-out.
Every family earns a place in the toolbox, and a rundown of the types of wood drill bits for construction and woodworking projects helps you match augers, Forstners, and spades to framing, trim, and furniture work.
Metal, Tile, and Glass Bits
Metal, tile, and glass punish ordinary bits quickly, so the material upgrade matters more than the drill that spins it.
Cobalt and Carbide for Hard Metals
Cobalt bits keep their edge at the temperatures stainless steel generates, and they should run at low speed with cutting oil. Carbide-tipped bits handle hardened fasteners, sheet metal, and abrasive composites without rolling the cutting edge. For thin sheet metal, a step bit or a sharp HSS bit at high speed leaves a burr-free hole.
Diamond Bits for Tile and Glass
Diamond-grit bits grind through porcelain and glass by abrasion, and water cooling keeps the heat from cracking the work. Without coolant, friction alone can shatter a tile or split a mirror seconds before the hole finishes.
A practical guide to types of drill bits groups the full lineup by material and job, which is useful when a project mixes wood, steel, and tile in one build.
Hole Saws, Step Bits, and Impact-Rated Tooling
Single-diameter bits cover most holes, but enlarging an existing opening or driving hundreds of screws calls for specialty tools.
Hole Saws and Step Bits
Hole saws cut large circles for doorknobs, pipe penetrations, and recessed lights, while step bits graduate through a range of diameters in one tool for sheet metal and electrical boxes. Each behaves differently at the drill, and a comparison of how hole saws, step drill bits, and wood boring bits handle different materials shows when to switch tools.
Impact-Rated Drill Bits and Driver Bits
Impact drivers deliver rapid rotational shocks that snap ordinary bits. Impact-rated drill bits use thicker webs and tougher steel, and the engineering behind impact-rated drill bits and screwdriver bit design improvements explains why reinforced geometry survives high-torque construction work. Driver bits get the same treatment, with hardened tips and torsion zones that absorb the hammering.
- Twist bit set from 1/16 to 1/2 inch for general work
- Brad point bits for finish carpentry and hardware
- Spade bits for fast holes in framing lumber
- Masonry bits for anchor holes in block and concrete
- Cobalt bits for stainless and hard steel
- A hole saw set for large penetrations