Wood Drill Bits: Forstner, Brad Point and Spade

Wood Drill Bits: Choosing the Right Bit for the Job

Drill bits have gotten confusing with all the sets and types flying around at the hardware store. As someone who has drilled thousands of holes across furniture builds, cabinet work, and rough framing, I learned the hard way which bit does what and why. Here’s everything I know — including the mistake I kept making before someone finally set me straight.

Brad Point Bits

Brad point bits feature a sharp center spur flanked by two outer cutting spurs, with relieved flutes that clear chips efficiently. The center spur locks the bit in position before the outer cutters engage, and the spurs score the wood fiber to prevent tearout at the entry hole.

Best Uses

Precision holes in solid wood where clean edges matter. Dowel holes, shelf pin holes, and any application where accuracy and appearance count. Took me three ruined boards to fully appreciate the no-walking entry — once you’ve used a brad point for shelf pins, you’ll never go back to a twist bit for that job.

Limitations

Brad points work best drilling perpendicular to the surface. Angled holes can cause the center point to deflect and wander. They’re designed for wood — don’t use them on metal or masonry unless you want a dull bit immediately.

Twist Bits

Standard twist bits — the ones most people picture when thinking “drill bit” — have helical flutes and a chisel-point tip. They’re versatile across materials but not optimized for wood specifically.

Best Uses

General-purpose drilling where precision isn’t critical. Pilot holes for screws. Any situation where you need a hole and don’t have a wood-specific bit at hand. That’s what makes them useful to have around — they’re the general-purpose option when you just need a hole and don’t much care how pretty it is.

Limitations

The chisel point tends to wander on entry, especially at an angle. Entry and exit holes may tear rather than cut cleanly. These bits work adequately but not excellently in wood — for finished work, reach for a brad point instead.

Forstner Bits

Forstner bits cut flat-bottomed holes with clean sides. A center point locates the hole while rim cutters define the circumference. That flat bottom is what distinguishes Forstners from every other type — and it’s the feature that makes them indispensable for cabinet work.

Best Uses

Hinge cup mortises, counterbores for washer seats, shallow decorative recesses, and any flat-bottomed hole. Overlapping cuts for mortising. Angled holes where other bits would wander off course. I reach for a Forstner whenever I’m cutting European hinge cups — 35mm, drill press, clean flat bottom every time.

Limitations

Forstner bits cut slowly and build up significant heat. Use drill press speeds appropriate to the diameter — larger bits need much slower speeds than smaller ones. Hand drilling with large Forstners is difficult to control and hard on the drill. I stick to the press for anything over about an inch.

Spade Bits

Spade bits feature a flat blade with a center point. They remove material aggressively and cost almost nothing — which tells you exactly where they fit in the pecking order.

Best Uses

Rough holes in construction framing. Running electrical wires through studs. Applications where the hole appearance is irrelevant because it disappears inside a wall. Budget-conscious drilling in non-critical work where you’d feel ridiculous spending $25 on a Forstner.

Limitations

Exit holes tear badly without backing material. The aggressive cutting action can grab suddenly in hardwoods. Holes aren’t clean enough for furniture-quality work. My shop rule: spade bits are for framing, never for finished work. I don’t mix that up anymore.

Auger Bits

Auger bits feature a threaded center point that pulls the bit through the wood, deep flutes for chip ejection, and cutting spurs that score the circumference. Frustrated by the effort of boring deep holes by hand, old-time woodworkers developed this self-feeding design — it evolved from brace-and-bit work into the modern auger bits used in timber framing today.

Best Uses

Deep holes in thick stock. Timber framing connections. Applications requiring clean holes through significant depth — 4″, 6″, or more. The self-feeding action pulls the bit through without requiring you to lean hard on the drill, which matters over a long day of boring.

Limitations

Power drill use requires good speed control — the self-feeding can be aggressive and grab if you’re not ready. Backing out can be difficult when chips pack into the flutes. Generally overkill for shallow holes in furniture work.

Countersink Bits

Countersink bits cut the conical recess that lets a screw head sit flush or below the surface. Some designs combine pilot hole drilling and countersinking in one pass — and those combo bits are the ones I use for almost everything now. Wish I’d known about them when I started. I spent a long time drilling two separate holes where one pass would have done the job.

Best Uses

Preparing screw holes for flush-mounted fasteners. Combination bits size the pilot hole and countersink for specific screw diameters, which removes the guesswork. Essential for furniture where exposed screw heads need to be hidden under wooden plugs.

Limitations

Match the countersink angle to your screw heads — 82 degrees is standard for most wood screws. Cutting too deep prevents the head from seating properly. Practice depth control on scrap before committing to your project wood.

Plug Cutters

Plug cutters create wooden plugs from your actual project material. The plugs fill counterbored screw holes, hiding fasteners under matching wood rather than store-bought dowels or contrasting filler. I’m apparently someone who is particular about grain-matched plugs — once you’ve used them on a nice piece of furniture, a bag of generic brown plugs never looks right again.

Best Uses

Creating grain-matched plugs from project offcuts. Match plug cutter diameter to your counterbore size — 3/8″ covers most furniture work. Orient the grain on your plug stock so it runs the right direction and the plugs will practically disappear after a little sanding.

Bit Quality and Care

Quality Matters

Cheap bits dull quickly, cut roughly, and snap under stress. Quality bits from reputable manufacturers cost more but perform better and last considerably longer. Invest in commonly used sizes — a good brad point set and a handful of key Forstner sizes will handle most of what you need.

Sharpening

Brad point and Forstner bits can be resharpened with small files and diamond stones. The investment in sharpening skills extends bit life considerably. A sharp Forstner cuts in a fraction of the time of a dull one. Badly chipped or damaged bits may need professional resharpening, but regular touch-ups are easy to do yourself.

Storage

Store bits where cutting edges can’t contact each other or other metal. Index cases, wooden blocks with drilled holes, or individual sleeves all protect the edges. Rust prevention matters especially in a damp shop — a light coat of oil before long-term storage goes a long way.

Speed and Feed

Larger bits need slower rotation speeds — this is the rule most beginners violate, and it’s why their Forstners burn and their holes come out rough. Drill presses with adjustable speed work best for large Forstners and augers. Feed pressure should produce steady chip ejection without generating excessive heat.

Let the bit do the cutting — forcing it creates heat, dulls the edge faster, and can cause sudden grabbing. On deep holes, withdraw periodically to clear chips and give things a chance to cool down.

Essential Bit Sets

Start with a brad point set covering common sizes (1/8″ through 1/2″). Add Forstner bits as specific projects demand — 35mm for European hinges, 1/4″ or 5mm for shelf pins, and whatever counterbore size you use most. Build the collection based on actual project needs rather than buying complete sets full of sizes you’ll never touch.