Design & DIY

7 drill bits and their uses

There’s more than one lure in your tackle box—why would your tool box have just one type of drill bit? Get the right gear and be more productive, whether you’re boring holes or reeling in dinner.

Brad point bit
Used only for drilling wood, this bit enters cleanly and, thanks to the sharp cutting points, leaves a crisp edge and a mostly flat bottom on the hole. The centre spur makes positioning the bit easy and prevents bit-wander as you start drilling.

Countersink bit
Cuts a conical hole so a fastener head sits flush with the surface of the surrounding material. The hole’s chamfered sides match the angle of the screw’s head; when you tighten the screw, the wood won’t split.

Auger bit
This is the go-to bit for deep holes. The screw-like threads of the point pull the bit into the wood, and the deep flutes act like an auger to back wood shavings up and out of the hole.

Twist bit
Designed to drill metal, in a pinch this familiar bit can do double duty on wood. When drilling metal, use a low speed and lubricant to keep the bit cool. Speed it up for wood and pull it out often to help clear waste.

Spade bit
A staple of any tool box, the humble spade is an inexpensive bit, designed for drilling deep or wide holes. Clear debris often as you drill, and be careful: These bits tend to bind in the hole and can torque the drill, causing injury.

Forstner bit
Leaves a clean, flat-bottomed hole, such as the ones you’ve seen in your cabinet doors for European-style hinges. Forstners are available from 1/8″ to at least 6″ dia.—use a drill press for large sizes.

Step bit
This is the bit to use for drilling sheet metal. The unusual stepped design enables you to drill whatever hole dia-meter you need without changing bits. The shearing action of the cutting edge leaves clean and burr-free holes.

Masonry bit
Brick, mortar, concrete, and stone are no match for the specialized carbide tip and deep fluting of masonry bits. Although you can use these bits in a regular drill at low speed, they’re most effective in a hammer drill.