A drill bit is a cutting tool, not just a metal rod that spins. Each type is engineered for a specific material and a specific kind of hole — and using the wrong one produces torn edges, rough holes, burning, or a broken bit. The right bit for the job takes seconds to identify once you know the differences.
Here’s every common drill bit type, what it’s for, and how to recognize it.
The standard bits most people own
Twist bits (jobber bits)
The most common bit — the standard cylindrical bit with a helical flute. Available in every drill set. Works in wood, plastic, and metal.
Use for:
- General-purpose drilling in wood (when hole quality isn’t critical)
- Drilling in metal (use HSS or cobalt, not standard wood bits)
- Plastic, composite materials
- Pilot holes before driving screws
Identify by: Pointed tip with two cutting edges, helical flutes running the length of the bit.
The limitation in wood: Twist bits tend to tear the wood fibers at the exit point (blowout), especially in plywood and softwood. For clean holes, use a brad-point bit instead.
Brad-point bits (spur-point bits)
A twist bit with a sharp center point and two outer spurs. The center point registers exactly on your mark before the outer spurs score the wood fibers, then the cutting edges remove the material. Produces cleaner, more accurate holes in wood than standard twist bits.
Use for:
- Woodworking where hole location and edge quality matter
- Drilling holes for dowels, hinges, hardware
- Any time you need a clean entry on the wood surface
Identify by: Sharp center point with two raised spurs on the outer edges.
Does not work in metal. The spur geometry is designed for wood fibers — it will snap in metal.
Spade bits (paddle bits)
A flat, paddle-shaped bit with a center point and two flat cutting wings. Fast material removal, rough holes. Inexpensive.
Use for:
- Large holes in wood where appearance doesn’t matter — running wire through studs, rough carpentry
- Holes 3/8” – 1-1/2” diameter where a hole saw isn’t available
Identify by: Flat paddle shape, wide and thin.
The limitation: Produces rough holes with significant tearout. For furniture or finish work, use a Forstner bit instead. The flat cutting edges also burn at high speed — use moderate speed and clear chips frequently.
Forstner bits
A cylindrical bit with a flat bottom, center point, and circular cutting rim. Removes material within the circle cleanly and produces a flat-bottomed hole. The most precise boring bit for woodworking.
Use for:
- Cabinet hinges (Euro cup hinges require 35mm Forstner holes)
- Any flat-bottomed recess or pocket
- Overlapping holes (the circular rim can cut accurately even when part of the bit hangs over a previous cut or the edge of the board)
- Large, clean through-holes in wood
Identify by: Cylindrical body with a flat cutting face, visible rim teeth.
Speed: Forstner bits require low speed, especially in larger diameters. 35mm Forstner at 500–800 RPM. High speed causes burning and dulls the bit rapidly.
Search for Forstner bit set on Amazon
Hole saws
A cylindrical saw blade that cuts a circle by sawing the perimeter, not drilling the full diameter. Used for large-diameter holes — plumbing penetrations, doorknob holes, electrical boxes, speaker cutouts.
Use for:
- Holes 1” – 6”+ diameter in wood, drywall, plastic, thin metal
- Doorknob holes (2-1/8” standard), deadbolt holes (1”)
- Electrical box cutouts (4”)
- Thin sheet metal (with appropriate TPI blade)
Identify by: Cylindrical cup shape with saw teeth around the rim, arbor with a pilot drill bit in the center.
Tip: The pilot bit guides the hole saw. Mark your center, start the pilot bit, then let the saw engage. Use low speed. Clear the plug from inside the hole saw frequently — it jams when full.
Search for hole saw kit on Amazon
Specialty bits
Countersink bits
Drills a pilot hole and a countersink (conical recess for the screw head) in one step. Produces a clean, flush screw installation.
Use for: Driving screws flush or below the wood surface for plugging. A countersink set matched to screw sizes (adjustable stop collar, combination bit) is one of the most useful accessories for furniture work.
Search for countersink bit set on Amazon
Step bits (step drills)
A cone-shaped bit with multiple stepped diameters. Drills thin materials (sheet metal, plastic, thin wood) and automatically de-burrs. One bit covers a range of hole sizes.
Use for: Sheet metal, electrical boxes, thin stock. Not appropriate for thick wood.
Masonry bits
Carbide-tipped bits designed for concrete, brick, stone, tile, and mortar. The carbide tip hammers and scrapes rather than cutting — masonry bits are used in hammer drill mode, not standard drilling mode.
Use for: Drilling into concrete, masonry, brick, or stone. Must use a hammer drill or rotary hammer.
Identify by: Carbide (gray, wide) tip at the business end, usually marked “masonry” or with a specific shank type.
Do not use in wood or metal — the wrong geometry produces poor holes and wastes the carbide tip.
Bit material: what the steel matters
HSS (High Speed Steel): Standard for most twist bits. Works in wood, soft metals, plastics.
Cobalt: HSS with cobalt added. Harder and more heat-resistant. Better for stainless steel and harder metals.
Carbide-tipped: Brazed carbide at the cutting edge. Used in masonry bits, some Forstner bits, and specialty wood bits. Very hard, not flexible — don’t flex or snap these.
Black oxide coated: Standard HSS with a coating that reduces friction and improves heat resistance. Moderate improvement over uncoated HSS.
Titanium nitride (TiN) coated: Gold-colored coating. Marketing term on many consumer sets — marginal improvement over HSS, coating wears off quickly on regrinding.
For wood drilling: standard HSS or brad-point bits are fine. For metal: cobalt or good HSS. For masonry: carbide-tipped in a hammer drill.
Recommended starter set
A practical drill bit kit for most DIYers:
- Twist bit set (HSS, 1/16”–1/2”): covers metal, plastic, general wood
- Brad-point set: covers precision woodworking holes
- Forstner set (15mm–50mm): cabinet work, clean large holes
- Masonry set: concrete anchors, wall mounting
Search for drill bit set complete woodworking on Amazon
FAQ
Why does my bit smoke and burn in wood?
Too fast, dull bit, or not clearing chips. Lower the speed, back the bit out every few seconds to clear chips, and replace dull bits. Burning happens fastest with spade bits and Forstner bits at too-high RPM.
Can I use a wood bit on metal?
Brad-point and Forstner bits: no. Standard twist bits: technically yes, but a bit designed for metal (HSS, cobalt) will last much longer and cut cleaner in metal. In a pinch, a standard twist bit works in soft metals (aluminum, thin sheet). Not in steel.
What size pilot hole before driving a screw?
The pilot hole should be slightly smaller than the screw shank (not the threads). A general guideline: use a bit that matches the screw shank diameter, not the outer thread diameter. The threads should still bite the wood; the shank shouldn’t split it.
My Forstner bit keeps burning. What’s wrong?
Speed too high. Forstner bits (especially large ones — 35mm+) need to run slowly. 500–1,000 RPM maximum. At high speed, the rim teeth generate significant heat and dull immediately.