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Choosing a wood bit depends less on the drill brand than on the hole you need. A clean dowel hole, a square-ended mortise, and a 2-inch cable pass-through each favor a different cutter. Using the wrong bit can leave a ragged exit, overheat the drill, or produce a hole that is too loose for the joint.
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What we cover
Quick picks by job
| Job | Best bit type | What to expect |
|---|---|---|
| Dowel holes | Brad-point bit | Accurate starting point and clean edges |
| Mortise waste removal | Forstner, brad-point, or auger bit | Removes material before chiseling |
| Small cable holes | Spade bit | Fast and inexpensive, but rougher |
| Large cable holes | Hole saw or self-feed bit | Cleaner large openings with more drill resistance |
Best bits for dowel holes
Use a brad-point wood bit set for most dowel work. Its center point locates the hole, while the outer spurs score the wood fibers before the main cutting edges enter. That produces a cleaner, more accurately positioned hole than a general-purpose twist bit.
For a 3/8-inch dowel, use a 3/8-inch bit rather than relying on a nominally similar metric size. If the fit is too tight, the dowel may split the workpiece or refuse to seat after glue is added. Test the bit and dowel in scrap from the same board. Hardwood, plywood, and softwood can all produce slightly different fits.
Drill at a moderate speed and keep the bit straight. A drill guide or doweling jig is a worthwhile upgrade when the holes must align across two boards. Drill slightly deeper than the inserted dowel—usually about 1/16 to 1/8 inch extra—so glue has somewhere to collect. Clear chips by lifting the bit every few seconds instead of forcing it continuously.
For shallow, flat-bottomed holes, a Forstner bit set can work well, especially when drilling on a drill press. For hand-held drilling, its broad rim creates more friction and demands better control. A brad-point bit is usually the cheaper and easier choice for ordinary dowel joints.
Bits for mortises
A drill bit does not create a finished rectangular mortise by itself. The normal process is to drill or bore away most of the waste, then square the ends and sides with a chisel or use a router with a suitable bit. Drilling a row of overlapping holes is often faster than trying to chisel the entire cavity from solid wood.
For a hand-held drill, use a brad-point bit when accurate depth and clean entry matter. A Forstner bit is better when you want a flat bottom and controlled edges, but it cuts slowly in deep hardwood and can stall a compact cordless drill. An auger bit pulls itself into the wood and clears chips effectively, making it useful for deeper mortises, though it can grab aggressively as it breaks through.
Set a depth stop or wrap painter’s tape around the bit. Stop at least 1/8 inch short of the final mortise depth if you plan to clean the bottom with a chisel. Drill a row of holes inside the layout lines, leaving enough material between holes to support the bit. Then pare away the webs and square the corners.
A hammer drill should be switched to standard drilling mode for wood. Hammer action can tear the fibers, enlarge the hole, and damage the bit’s cutting edges. An impact driver is also a poor first choice for precision mortises because its hammering action makes depth and alignment harder to control. It can drive hex-shank boring bits in rough framing work, but not where a tight woodworking fit is required.
Large holes for cables and pipes
For holes from roughly 1/2 to 1-1/2 inches, a wood spade bit set is the inexpensive option. Spade bits cut quickly and are easy to replace, making them suitable for running electrical cable through studs, joists, and cabinet parts. They leave a rougher edge than a hole saw, especially when the bit exits the back of the board.
To reduce blowout, mark both faces and drill from one side until the center point or pilot screw appears on the opposite face. Finish from that side. You can also clamp a scrap board tightly against the exit face. Do not force a large spade bit with a small drill; the wide paddle can catch suddenly and twist your wrist.
For larger, cleaner holes, choose a wood hole saw kit with a mandrel. Hole saws are a good choice for cable pass-throughs visible in furniture, worktops, or paneling. They remove a circular plug, which creates more drag than a spade bit. Use low to medium speed, keep the saw square, and withdraw it periodically to clear chips.
Self-feed bits are faster in framing lumber and are available in sizes commonly used for plumbing and cable runs. Their threaded center screw pulls the cutter forward, so they require less pushing but can pull the drill into the work unexpectedly. They also need a high-torque drill and are less forgiving in thin panels. For a clean hole through a cabinet side, a hole saw is usually the better trade-off.
Match the bit to the drill
Small brad-point bits work well in nearly any cordless drill. Bits around 1 inch and larger need more torque, a fully charged battery, and a side handle if the drill accepts one. Use the lowest useful gear and a firm two-handed grip. If the drill repeatedly stalls, overheats, or smells of burnt wood, stop and clear the bit rather than increasing pressure.
Check the bit length before drilling into a stud or cabinet. For cable work, identify hidden wiring, plumbing, and fasteners before boring. In framing, follow local electrical rules for hole placement and protective nail plates. Wear eye protection, especially with spade bits and hole saws, and remove the battery before clearing a jammed cutter.
What to buy first
For general DIY work, start with a quality brad-point set, then add a spade-bit set if you regularly run cables. Buy Forstner bits individually in the sizes you actually use rather than purchasing a large set immediately. Add a hole saw kit when large holes need a cleaner appearance. The cheaper option is fine for occasional hidden cable holes; sharper, better-ground bits matter most when the hole is part of a visible joint or must repeat accurately.