Wood Bits, Masonry & Metal Drill Bits: Complete Selection Guide

Wood bits, masonry drills, and metal drill bits are not interchangeable — using the wrong bit for the material damages both the bit and the workpiece, produces poor-quality holes, and creates safety risks. The core rule is straightforward: use brad-point or spade bits for wood, carbide-tipped bits for masonry and concrete, and high-speed steel (HSS) or cobalt bits for metal. Each category has distinct geometry, tip design, and material hardness matched to how that substrate cuts, fractures, or abrades. This guide covers every major bit type within each category, with specific recommendations for drill speed, bit selection by application, and how to extend bit life.

Wood Drill Bits: Types, Geometry, and Best Uses

Wood is a relatively soft, fibrous material that cuts rather than abrades. Wood drill bits are designed with sharp cutting edges that sever wood fibers cleanly, a geometry that centers the bit accurately, and flute designs that evacuate chips efficiently to prevent binding and burning. The variety of wood bit types reflects the range of hole sizes, depth requirements, and finish quality demands encountered in woodworking.

Twist Bits for Wood

Standard HSS twist bits work in wood but are not optimized for it. Their conical point tends to wander on smooth wood surfaces and the cutting geometry produces a rougher hole edge than dedicated wood bits. For quick utility holes where appearance is not critical — pilot holes for screws, rough framing work — a standard twist bit is adequate. For anything requiring a clean, accurate hole, a dedicated wood bit is worth the marginal additional cost.

Brad-Point Bits: The Standard for Precision Wood Holes

Brad-point bits have a sharp center spur that registers precisely in the wood surface before the outer cutting spurs engage, preventing wander at the start of the hole. The two outer spurs score the hole perimeter before the main cutting lips remove material from inside the scored circle, producing a clean, tear-free hole edge on both face grain and cross-grain surfaces. Brad-point bits are the standard choice for cabinetry, furniture making, and any application where hole location precision and edge quality matter. Available in diameters from 3 mm to 25 mm (1/8 to 1 inch), they are the most versatile wood-specific bit for a standard drill or drill press.

Spade Bits: Fast Material Removal at Lower Cost

Spade (paddle) bits use a flat blade with a center point and two cutting corners. They drill quickly and cheaply in the 16–50 mm (5/8 to 2 inch) range where brad-point bits become expensive and Forstner bits are slower. Hole quality is acceptable for rough carpentry — drilling holes for cable routing, pipe penetrations, and rough-in work — but edge quality is significantly rougher than brad-point or Forstner bits, and tearout on the exit face can be significant without a backing board. Spade bits require higher feed pressure than other wood bits and overheat quickly if not used at appropriate speed.

Forstner Bits: Flat-Bottom Holes and Maximum Edge Quality

Forstner bits produce flat-bottomed, clean-edged holes with minimal tearout — essential for hinge mortises, dowel sockets, and decorative woodworking. The rim-cutting design allows the bit to drill partial holes at a board edge, overlapping holes, and holes at angles without wandering. Forstner bits require a drill press for best results — the high torque generated by the large rim diameter makes them difficult to control in a handheld drill, and they must be run at slow speeds: 250–500 RPM for sizes above 25 mm. Available from 10 mm to 100 mm diameter.

Auger Bits: Deep Holes in Timber

Auger bits have a screw-tip center point that pulls the bit into the wood under its own thread action, a single deep spiral flute that aggressively evacuates chips, and cutting spurs for clean perimeter scoring. They excel at drilling deep holes — through beams, thick timber, and stacked lumber — where standard bits would clog with chips and bind. Electrician's bell-hanger auger bits extend this principle to 450–900 mm lengths for routing wire through wall cavities and floor joists.

Hole Saws for Wood

Hole saws use a cylindrical saw-tooth cup to cut large-diameter circles, leaving the central core intact. They cover diameters from 25 mm to 200 mm — the range above what Forstner bits practically cover — and are the correct tool for door locksets, plumbing penetrations, and recessed light cutouts. Bi-metal hole saws cut wood, thin wood composites, and drywall; carbide-grit hole saws cut harder materials. Use slow speeds (300–600 RPM for sizes above 50 mm) and withdraw periodically to clear chips.

Drill Speed and Feed Rate for Wood

Wood bits require higher speeds than masonry or metal bits of equivalent diameter. As a general rule, smaller diameter bits run faster and larger bits run slower to keep the peripheral cutting speed (the speed at the outer cutting edge) within the optimal range. Burning at the hole edge — indicated by black scorch marks and a burning smell — means the bit is running too fast, too slow with excessive feed pressure, or has dull cutting edges. Sharp bits at the correct speed produce clean chips, not dust, and cut without significant heat.

Masonry Drill Bits: Carbide Tips, Hammer Action, and Material Considerations

Masonry materials — concrete, brick, block, stone, and tile — are hard and brittle. They cannot be cut by a rotating edge alone; they must be fractured and pulverized by the impact of a hard tip, then cleared from the hole by the rotating flutes. Standard rotary drilling without hammer action is ineffective in dense concrete — it glazes the hole surface and destroys the bit without making meaningful progress. The correct tool is a hammer drill (rotary hammer action) with a carbide-tipped masonry bit for most concrete and masonry applications; a rotary-only drill with a masonry bit works adequately in softer brick and lightweight block.

Standard Carbide-Tipped Masonry Bits

Standard masonry bits have a tungsten carbide insert brazed to the tip of a steel body. The carbide insert — typically sintered WC-Co with 85–92% WC content — is ground to a chisel-point geometry that fractures masonry under impact loading. The steel body's spiral flutes carry the powdered debris out of the hole. These bits fit in standard 3-jaw drill chucks and are used in both standard drills and hammer drills. For light-duty use in brick and block, they perform well; for reinforced concrete or repeated deep holes, SDS-Plus or SDS-Max bits in dedicated rotary hammers are significantly more productive and durable.

SDS-Plus and SDS-Max Bits for Rotary Hammers

SDS (Slotted Drive System) bits have a specialized shank with locking grooves that allow the bit to slide axially within the chuck while being rotationally driven — enabling the rotary hammer's piston mechanism to deliver hammer blows directly to the bit without those blows being transmitted to the operator's wrist through the chuck. SDS-Plus is the standard for bits up to approximately 26 mm diameter; SDS-Max handles bits from 16 mm to 80+ mm for heavy foundation drilling and large anchor installations. The energy delivered per blow in an SDS-Max rotary hammer is typically 8–25 joules, compared to 1–5 joules for SDS-Plus — the difference between drilling a 10 mm anchor hole in 5 seconds versus drilling a 40 mm core hole through a 300 mm wall in under a minute.

Core Drill Bits for Large Diameter Masonry Holes

For holes above 50 mm in concrete and masonry — pipe penetrations, HVAC sleeves, electrical conduit entries — diamond core drill bits mounted in a core drill machine are the professional standard. Diamond core bits use a steel tube with diamond-impregnated segments on the cutting rim; they cut by grinding rather than impact and require water cooling to prevent diamond bond degradation. A 100 mm diamond core bit drilling through 200 mm of reinforced concrete typically takes 3–8 minutes and produces a smooth, cylindrical hole with no spalling at the entry or exit face — a quality level impossible to achieve with hammer drilling.

Drilling Tile Without Cracking

Ceramic and porcelain tile requires a different approach from concrete masonry. Never use hammer action on tile — the impact shatters the glaze and cracks the tile body. Use a carbide-tipped spear-point tile bit in rotary-only mode at moderate speed (400–800 RPM) with light, steady feed pressure. For porcelain tiles with hardness above 7 Mohs, diamond-grit hole saws or diamond-core bits in rotary mode with water cooling are the correct tools — carbide tips dull rapidly in hard porcelain and produce chipped hole edges. Starting the hole with a center punch or a piece of tape on the tile surface prevents the bit from skating across the glazed surface.

Practical Tips for Masonry Drilling

• Check for rebar before drilling: Rebar detectors (available for $30–$80) locate reinforcing steel before drilling. Drilling into rebar destroys carbide bits immediately and can be dangerous if the drill binds. In reinforced concrete, plan hole locations to avoid rebar lines.
• Use correct hammer drill speed: Masonry bits in hammer drills run at lower speeds than metal or wood — typically 400–1,200 RPM for standard masonry bits. High speed without adequate impact energy glazes the hole; low speed with high impact energy is more productive in dense concrete.
• Withdraw regularly to clear debris: Pulling the bit partway out every 30–60 seconds while keeping it spinning clears masonry dust from the flutes, prevents binding, and reduces heat buildup in the carbide tip.
• Never use water cooling with standard hammer drills: Water cooling is for dedicated core drill machines. Using water with a standard hammer drill risks electrical shock. Air-cooling through regular bit withdrawal is sufficient for standard masonry bits.

Metal Drill Bits: Materials, Coatings, and Technique

Metal drilling generates heat through cutting friction — managing that heat is the central challenge of metal drill bit selection and technique. Metal bits must be harder than the material being drilled, maintain a sharp cutting edge at elevated temperature, and have flute geometry that efficiently removes metal chips before they re-cut and generate additional heat. The wrong bit material, wrong speed, or wrong feed pressure in metal drilling results in work hardening of the hole surface, bit tip breakage, or catastrophic bit failure.

High-Speed Steel (HSS) Bits: The General-Purpose Standard

HSS (High-Speed Steel, typically M2 grade containing tungsten, molybdenum, chromium, and vanadium) is the baseline material for metal drill bits. HSS bits maintain hardness up to approximately 600°C (1,100°F) — sufficient for drilling mild steel, aluminum, copper, brass, and most non-ferrous metals at moderate speeds with cutting fluid. Standard HSS bits are available in the widest range of sizes at the lowest cost and are appropriate for general workshop and maintenance use where material being drilled is not hard or abrasive.

HSS-Co (Cobalt) Bits: For Harder Steels and Stainless

Cobalt HSS bits (M35 with 5% Co, or M42 with 8% Co) maintain hardness at temperatures up to 700–735°C and are significantly more wear-resistant than standard HSS in abrasive materials. For drilling stainless steel, hardened steel, cast iron, titanium, and high-nickel alloys, cobalt bits are the correct specification. M42 cobalt bits drilling 304 stainless steel last 3–5 times longer than standard HSS bits under identical conditions, justifying their 2–3× price premium for production use. Cobalt is alloyed throughout the steel matrix, not just a surface coating — cobalt bits can be resharpened multiple times without losing performance, unlike coated bits where resharpening removes the coating.

Carbide-Tipped and Solid Carbide Bits

Solid carbide drill bits offer the highest hardness and wear resistance of any drill bit material — tungsten carbide at Rockwell A hardness of 90–93 HRA versus HSS at approximately 83–86 HRA. Solid carbide bits are used in CNC machining centers drilling hardened steel, cast iron, and composite materials where HSS and cobalt bits dull too quickly for economical production. They require rigid, vibration-free setups — carbide is brittle and shatters if side-loaded or subjected to drill walk — making them impractical for handheld drilling. Carbide-tipped (brazed) bits offer a compromise: carbide cutting edges with a tougher steel body, used in specialized metal drilling and tile drilling applications.

Drill Bit Coatings and What They Actually Do

• Black oxide: The most basic treatment — oxidized surface that provides minimal corrosion resistance and marginal lubricity improvement. Mainly reduces friction slightly during chip evacuation. Not a performance coating; primarily a corrosion protection for storage. Common on standard HSS bits.
• Titanium Nitride (TiN — gold colored): PVD coating that increases surface hardness to approximately Vickers 2,300 HV and reduces friction coefficient. Extends bit life 2–3× versus uncoated HSS in mild steel. Cannot be resharpened without removing the coating. Effective for production runs in mild steel and aluminum.
• Titanium Carbonitride (TiCN — blue-gray): Higher hardness than TiN (~3,000 HV) with better wear resistance. Preferred over TiN for abrasive materials and higher-temperature cutting applications.
• Titanium Aluminum Nitride (TiAlN — dark gray/purple): The highest-performance common coating — maintains hardness at temperatures above 800°C and forms an aluminum oxide barrier layer at cutting temperatures that further reduces friction. Preferred for stainless steel, hardened steel, and dry machining where cutting fluid cannot be used.

Correct Drill Speed for Metal

Metal drilling requires significantly lower RPM than wood drilling. The correct speed is calculated from the recommended surface cutting speed for the material-bit combination, divided back to RPM by the bit diameter. As a practical reference: a 6 mm HSS bit drilling mild steel should run at approximately 800–1,200 RPM; the same bit in stainless steel should run at 300–500 RPM with consistent feed pressure to avoid work hardening. Drilling stainless too slowly with insufficient feed pressure is as damaging as drilling too fast — the bit rubs without cutting, work-hardens the surface, and dulls immediately.

Choosing Between Bit Types: A Cross-Material Quick Reference

In practice, many drilling tasks involve composite situations — drilling through wood into concrete, through metal into masonry, or through multiple materials in sequence. Understanding the compatibility limits of each bit type prevents damage and wasted effort.

• Wood into concrete (e.g., securing a timber ledger to a masonry wall): Drill through the wood with a brad-point or twist bit first, then switch to a masonry bit and hammer mode for the concrete anchor hole. Do not attempt to use the masonry bit through the wood — the carbide tip geometry produces a rough, oversized hole in wood.
• Metal plate against a concrete wall: Drill the metal with an HSS bit first, then use the hole as a guide template and switch to a masonry bit for the concrete. Attempting to drill both with a masonry bit destroys the HSS body; attempting both with an HSS bit produces no progress in concrete.
• Multi-material bits: Some manufacturers produce "universal" bits marketed for wood, metal, and masonry. These are compromise designs that work adequately in all three materials but excel in none. For occasional use in mixed materials where switching bits is inconvenient, they are acceptable; for any task requiring quality holes or production volume, dedicated bits for each material are always superior.
• Step drill bits for sheet metal: Step drills (cone-shaped bits with multiple stepped diameters) are the most efficient tool for drilling multiple sizes in thin sheet metal (up to 3–4 mm thick) — one bit covers diameters from 4 mm to 30 mm in a single stepped profile, eliminating bit changes. They produce clean, burr-free holes in sheet steel, aluminum, and plastic and are standard in electrical panel work and automotive sheet metal.

Extending Drill Bit Life: Sharpening, Storage, and Common Mistakes

Drill bits are consumables, but their service life varies enormously based on how they are used, stored, and maintained. A quality cobalt bit used correctly can drill hundreds of holes in steel; the same bit used at wrong speed without cutting fluid may fail after ten holes.

• Use cutting fluid consistently in metal drilling: Cutting oil, tapping fluid, or even general-purpose oil dramatically reduces tip temperature and extends edge life. Stainless steel drilled dry dulls HSS bits 5–10 times faster than the same operation with proper cutting fluid. For aluminum, WD-40 or light machine oil prevents chip welding to the flutes.
• Apply consistent feed pressure: Inconsistent, pecking feed pressure in metal causes the bit to rub rather than cut on the upstroke, generating heat without chip removal. Consistent, firm downward pressure keeps the cutting edge engaged and the chip forming continuously.
• Store bits in indexed cases, not loose: Loose bits in a toolbox damage each other's cutting edges through contact. Indexed drill index cases or bit rolls that keep each size separated and protected preserve edge geometry for significantly longer service life.
• Resharpen HSS and cobalt bits before they are completely dull: A slightly dull bit resharpened early requires minimal material removal and restores full performance. A completely destroyed bit may require removing so much material that the correct drill geometry cannot be restored. Handheld bit sharpening guides and dedicated drill sharpening machines produce accurate point angles and symmetric cutting lips for bits from 3–13 mm.
• Never use masonry bits without hammer action in dense concrete: Running a masonry bit at high speed in rotary-only mode in concrete glazes the carbide tip and destroys it within minutes. If your drill does not have hammer mode, use it only in soft brick or lightweight block — not dense concrete.