Types of Drill Bits: Uses for Wood, Metal & Tile

For tough stainless steel, cobalt is better; for everyday metal on a budget, titanium is plenty. Titanium bits are HSS with a heat-lowering coating, so they drill general metal well but give up that edge once sharpened. Cobalt bits are a steel-and-cobalt alloy all the way through, so they run harder, resist heat, and can be reground many times, though they are more brittle and cost more.

Cobalt bits are worth it if you regularly drill hard metals like cast iron or stainless steel, where they far outlast standard bits. For general wood, plastic, or soft aluminium, they are overkill: a standard HSS or titanium bit costs less and is less likely to snap, since cobalt’s hardness also makes it brittle.

A bit’s color usually signals its coating or material, not just its looks. Black means black oxide (standard HSS), gold points to a titanium nitride coating that resists heat, dull gray is typically cobalt for hard metal, and bright silver is often plain HSS or aluminium. Check the packaging, though, because some budget brands paint bits to imitate a coating they do not have.

A carbide drill bit uses tungsten carbide, the hardest material commonly found in bits, either as a brazed tip or as the whole body. Carbide stays sharp far longer than steel and shrugs off heat, which is why it tips masonry bits and forms industrial metal bits. The trade-off is that it is brittle, so it is reserved for masonry, tile, and high-speed production rather than general use.

The number is the angle of the bit’s tip, and it changes how the bit cuts. A 118-degree point is sharper and more aggressive, which suits wood and soft metals, while a flatter 135-degree point engages the material sooner and drills hard metals more cleanly. A 135-degree split point grinds two extra edges into the tip so the whole point cuts, which lowers the push needed and keeps the bit from walking on steel.

For metal, match the bit to the metal’s hardness. Light aluminium drills fine with standard HSS, plain steel goes faster with a titanium-coated (gold) bit, and hardened or stainless steel needs a cobalt bit in a 5% or 8% grade. Whatever the metal, run a slow speed with cutting oil so the edge does not burn.

The best wood bit depends on the hole you want. Standard twist bits handle general holes, brad point bits give clean and precise ones, spade bits bore large rough holes for running cable or pipe, auger bits pull themselves through deep timber, and Forstner bits leave the flat-bottomed holes that cabinet hinges need.

You can spot a concrete (masonry) bit by its tip: a wide tungsten-carbide head shaped like an arrowhead or a small roof, clearly wider than the bit’s body. The shank may also be slotted for an SDS rotary hammer rather than smooth. If the tip is just a sharp point or a plain spiral, keep it away from concrete.

PDC stands for Polycrystalline Diamond Compact. These industrial bits are used mainly in oil and gas drilling to cut through deep rock formations. Their synthetic diamond cutters shear rock away instead of crushing it, so they keep cutting where a steel bit would quickly fail.

Solid carbide bits are the hardest and most wear-resistant, but that same hardness makes them brittle and easy to chip. For real-world toughness, the ability to cut hard material without snapping, cobalt alloy bits are usually the strongest choice for a homeowner or tradesperson.

To stop a bit from slipping or walking on smooth metal or tile, give it a place to bite. Tap a small dimple with a center punch before you drill, switch to a split-point bit whose reground tip self-centers, or stick masking tape over the spot so the tip has grip. Starting at a slow speed helps too.

Yes, you can sharpen most High-Speed Steel and cobalt bits on a bench grinder or a dedicated drill-bit sharpener. Titanium-coated bits are the exception: grinding them strips off the gold heat-resistant layer that makes them last, turning them back into plain steel.

The shank is the plain end that grips into your drill, and three types cover most jobs. A round (straight) shank is the most common and fits any keyed or keyless chuck, though it can spin under very high torque. A six-sided 1/4-inch hex shank locks into an impact driver or quick-change holder so it will not slip, while slotted SDS-Plus (10mm) and SDS-Max (18mm) shanks slide back and forth in a rotary hammer to deliver masonry impact.