How to Choose a Drill Bit: Material-to-Bit Matrix

The single most important question is what you're going into: soft wood, hardwood, sheet metal, hardened or stainless steel, concrete or block, or tile and glass. Each demands a different tip material and geometry, and using the wrong one either fails to cut or destroys the bit.

Quick matrix: wood - HSS or titanium twist bits (or spade/auger for big holes); soft metal/aluminum - HSS or titanium; hard or stainless steel - cobalt (M35); concrete/brick - carbide-tipped masonry bit, ideally SDS-plus in a rotary hammer; tile/glass - carbide or diamond spear-point; large holes in any material - a hole saw.

HSS (high-speed steel) is the baseline - fine for wood and plastic, okay for light metal. Titanium-coated HSS adds a hard TiN surface for more bite and roughly double the life, but the coating is only skin-deep, so it's a value upgrade, not a metal specialist.

Cobalt (M35/M42) is an alloy hardened all the way through - it runs cooler and cuts stainless and hardened steel that dull coated bits, and it can be resharpened. Carbide is harder still and is used as tips on masonry bits, tile bits and premium hole saws for abrasive or very hard material. Match the material to the metal and you stop wasting bits.

Point angle controls how the bit starts and cuts. A standard 118-degree point is general-purpose and works in wood and soft metal. A 135-degree split point is flatter and self-centering - it starts on contact without walking, which is why it's preferred for metal and hard materials.

For a clean start without a center punch, look for split-point or pilot-point tips. Masonry bits use a wide carbide head with a centering tip; tile/glass bits use a spear point; spade bits use a sharp center point with side spurs. The tip is what determines whether the hole starts where you aimed.

Round shanks are the traditional twist-bit style and go in any keyed or keyless drill chuck. Hex (1/4 in) shanks lock into impact drivers and quick-change chucks so they won't spin under torque - used on driver bits, spade bits and many quick-change accessories.

SDS-plus shanks are a different system entirely: they slot into a rotary hammer and let it deliver hammering blows, which is essential for drilling concrete efficiently. An SDS bit will not fit a normal drill chuck, and a round-shank masonry bit in a regular drill is slow and frustrating in real concrete.

Driver bits are not drill bits - they turn screws, not cut holes. If you use an impact driver, buy impact-rated driver bits (like FLEXTORQ) that flex to absorb torque instead of shattering, and match the tip exactly to the fastener (Phillips #2, Torx T25, square #2, etc.) to avoid cam-out and stripped heads.

A complete kit usually pairs a drill bit set for holes with a separate driver bit set for fasteners. Don't force round-shank drill bits into an impact driver - use hex-shank bits in impact tools, and reserve the drill's chuck for precise hole drilling.

Heat is what kills bits. Harder and larger the material, slower the speed: run big bits and metal slow, small bits in wood faster. Let the bit cut with steady, moderate pressure rather than leaning on it.

Use cutting oil in metal, back the bit out to clear chips, and let hole saws and spade bits clear their plugs. Store bits so tips don't knock together, and resharpen cobalt/HSS bits rather than tossing them - a sharp bit is safer and cuts cleaner than a dull one.