Understanding Drill Bits for Woodworking

Drill bits for woodworking have gotten complicated with all the types, coating options, and brand recommendations flying around. As someone who has used the wrong drill bit at the wrong time and paid for it in torn-out holes and splintered wood, I learned everything there is to know about which bit to reach for and when. Today, I will share it all with you.

The right drill bit makes a hole that looks intentional and fits its purpose. The wrong drill bit makes a hole that looks like something went wrong — torn grain on the exit, a rough sidewall, or a bottom that’s cupped when you needed it flat. Understanding what each bit type actually does is the difference between production work that goes smoothly and constant small frustrations.

Types of Wood Drill Bits

The twist bit is the starting point for most people — it’s what comes in that 29-piece general-purpose set that most workshops have somewhere. Twist bits work for general drilling in wood and are capable of reasonable results in small diameters. Their weakness is that they don’t have a center point to anchor the bit at the start of the hole, so they wander slightly on the work surface before finding their center. For precise hole placement, the brad point bit is a significant upgrade.

Brad Point Drill Bits

Brad point bits are what I reach for in most woodworking drilling situations. The sharp central point seats in the wood surface exactly where you place it, eliminating the walking that twist bits require you to prevent with a center punch. The outer spurs score the wood fibers before the bit excavates between them, which produces clean, crisp hole edges rather than the slightly torn edge a twist bit leaves. For hinge mortises, dowel holes, shelf pin holes, and any drilling where you care about the hole’s appearance or a close fit, brad points are the right call.

Spade Drill Bits

Spade bits are for when you need a large diameter hole fast and the appearance doesn’t matter much. I use them for running wires through framing, drilling large access holes in shop fixtures, and any application where a 3/4-inch or larger hole needs to go in quickly without precise cleanup. They leave a rougher hole edge than any of the other options and they require a pilot point to start accurately, but they’re inexpensive and fast, which counts for a lot in rough work.

Auger Drill Bits

Auger bits are the deep-hole specialists. The screw tip pulls the bit into the wood without requiring you to apply much forward pressure — it self-feeds. The wide flutes clear chips efficiently from deep holes. I’m apparently someone who tried to drill 4-inch deep holes for chair legs with a brad point bit once, and the chip clogging was a disaster. Auger bits handle that situation effortlessly. For through-hole mortises, deep pocket drilling, or any hole that goes significantly deeper than its diameter, an auger bit is the right tool.

Forstner Drill Bits

Forstner bits are the precision instrument of the drill bit world. They cut a flat-bottomed cylindrical hole with exceptionally clean walls and edges. That’s what makes Forstners endearing to us woodworkers doing cabinet hardware installation, pocket work, and anywhere a clean flat-bottomed hole is required. European cup hinges — the hinges used in virtually all frameless cabinetry — require a 35mm flat-bottomed hole that only a Forstner bit can produce cleanly.

Forstners can also drill overlapping holes — useful for waste removal in mortises and pockets — because they don’t need a full hole perimeter to guide themselves. The wide rim guides the bit accurately even when part of the rim is cutting into a previously drilled hole. A feature no other common bit type can match.

Choosing the Right Drill Bit

The quick guide I use: visible finish hole in a workpiece that people will see — brad point. Flat-bottomed hole for hardware — Forstner. Large rough hole fast — spade. Deep hole through thick stock — auger. General metal or mixed-material work — twist bit. If you’re unsure, brad point is usually the conservative default for woodworking because its self-centering and clean-edge characteristics are advantages in almost every situation.

Maintenance and Care for Drill Bits

Sharp drill bits cut clean holes; dull bits tear and burn. The most common sign of a dull brad point or Forstner bit is smoke coming from the hole during drilling — the bit is generating heat through friction rather than cutting. Slow down your feed rate before replacing a bit; sometimes the operator is pushing too hard rather than the bit being truly dull. But when a bit genuinely won’t cut cleanly regardless of technique, it’s time to sharpen or replace it.

• Store bits in a roll case or individual slots, not loose in a drawer where they bang against each other and dull the cutting edges.
• Clean resin and pitch off bits after use with blade cleaner — buildup reduces cutting efficiency.
• A drill bit sharpening jig for brad points and Forstners extends bit life significantly. The investment pays back quickly on quality bits.

Safety Tips

Secure the workpiece before drilling — a piece that spins when the bit catches it can cause injury. For small pieces, a drill press with a fence and hold-down is the right tool rather than a handheld drill. Always back up your workpiece with scrap when drilling through holes — the exit tearout on most bits without a backer board is significant, and removing it is more work than preventing it.

Drill at appropriate speeds for the bit type and wood species. Large Forstner bits run at slow RPM — 250 to 500 RPM for anything over an inch diameter. Running a large Forstner at high speed burns the wood and dulls the bit rapidly. Brad points in small diameters can run faster. Adjust speed based on bit diameter: larger diameter means slower speed.

Related Articles

• Enhance Your Wood Projects with Helmsman Spar Urethane
• Understanding Wood Mites: Tiny Helpers in Nature
• Exploring Diverse Clamps: A Handy Guide to Holders