Types of Drill Bits for Wood: A Complete Guide

Wood drill bits divide into seven main types — brad-point, spade, auger, Forstner, self-feed, installer, and countersink — and each one solves a different hole problem.

A brad-point bit bored into a cabinet door leaves a clean rim. The same hole cut with a metal twist bit tears the grain and wanders off your mark. That single difference explains why a woodworker’s bit index holds so many shapes: the geometry of the cutting tip determines whether you get a crisp hole, a fast hole, a deep hole, or a flat-bottomed pocket.

Below are the types that matter, what each is built to do, and the sizes the catalogs list.

Brad-Point, Spade, And Auger Bits: The Workhorses

Brad-point bits cut accurate, clean holes up to 1/2″, spade bits rip fast large holes through any wood, and auger bits bore deep holes while clearing chips as they go.

Brad-point bits carry a center spur that starts the hole exactly on your mark, with outside spurs that score the rim and stop breakout. Irwin’s catalog lists them from 1/8″ to 1/2″, the range most cabinetmaking and furniture work needs. This is the bit to reach for when tear-out would ruin the piece.

Spade bits pair a pointed center with a broad flat blade, and they cut fast through softwood, hardwood, and plywood.

Auger bits use a screw point to pull themselves into the wood and a wide spiral to lift chips out. That makes them the choice for deep holes where a spade bit would clog.

Forstner, Self-Feed, And Installer Bits: Holes With Special Demands

Forstner bits cut clean flat-bottomed holes at any angle, self-feed bits punch large repetitive construction holes, and installer bits run long straight channels for cable.

Forstner bits have multiple cutting teeth around a center guide point. That geometry gives you a smooth finish, lets you bore a blind hole with a flat bottom, and allows overlapping or angled holes a brad-point bit cannot manage. Carbide-tipped versions hold an edge longer in abrasive plywood and hardwood.

Self-feed bits have a self-feeding tip that drags the cutter into the wood, built for repetitive large holes on construction sites.

Installer bits are the long ones — 1/4″ to 3/4″ diameter, 12″ to 30″ long — with a hole near the tip so you can pull cable back through the channel you just drilled. Telecom and security installers live on these.

Chucks, Shanks, And Fit: What Decides The Outcome

Matching shank to chuck and bit length to material thickness decides whether the bit runs true or wobbles.

A 1/4″ hex bit needs a compatible chuck or holder, while a straight-shank bit needs a three-jaw chuck that can grip it squarely. Check that before you buy.

Two more fit points: match bit diameter to the hole you need, and match maximum drilling depth to how thick the material is. A bit that bottoms out mid-cut burns the wood and stalls the drill.

For abrasive plywood or hardwood, carbide-tipped bits stay sharp longer than tool steel. If you want a tested shortlist instead of chasing part numbers, our roundup of the best drill bits for woodworking compares the sets worth owning.

The biggest mistake is grabbing a general metal twist bit for fine woodwork. It wanders and tears the grain where a brad-point or Forstner would leave a clean edge. The second mistake is choosing a spade bit for a flat-bottom blind hole — that job belongs to the Forstner.