Using the wrong drill bit is one of the most common sources of frustration on the job site and in the workshop — slow cutting, wandering holes, overheating, and prematurely blunt bits. This guide explains which drill bit does which job, and what to look for when you're buying.
HSS Twist Drill Bits — For Metal and General Use
High-speed steel (HSS) twist bits are the most common drill bit type — the standard silver-grey bit that comes in every set. They're designed primarily for drilling metal but also work in timber, plastics, and composites.
HSS (Standard) — Suitable for mild steel, aluminium, copper, brass, and most plastics. Available in diameters from 1mm to 25mm. Ground point angles: 118° for general use, 135° split point for self-centring in metal without a centre punch.
HSS-Co (Cobalt) — Contains 5–8% cobalt for significantly improved heat resistance. Use for drilling stainless steel, hardened steel, cast iron, and other hard metals. Cobalt bits cost more but last considerably longer in demanding materials.
HSS-TiN (Titanium Nitride Coated) — Gold-coloured coating that reduces friction and extends bit life in general metal drilling. A cost-effective upgrade over standard HSS for regular metal work.
Timber Drill Bits — For Wood and Engineered Products
Brad Point (Dowel) Bits — The correct bit for precision holes in timber and MDF. The centre brad point pre-locates the hole precisely, and the outer spurs cut a clean circle before the main cutting edges remove the waste. Produces a clean, tear-out-free hole on the entry face.
Spade (Flat) Bits — Fast hole-boring in timber for cable runs, pipework, and structural holes. Available in 10–50mm diameter with a 1/4 inch hex shank. Cheap, fast, and acceptable finish quality for hidden holes in framing.
Auger Bits — The electrician and plumber's preferred bit. A screw-tip lead point draws the bit through timber without force, providing cleaner entry and exit holes than a spade bit. Excellent in solid hardwood. Available in 12–38mm in standard lengths, with extended versions (300–600mm) for boring through multiple studs from one position.
Forstner Bits — For flat-bottomed holes and overlapping holes in timber — essential for concealed hinge cups (European hinges), furniture making, and cabinet installation. Produce a perfectly flat-bottomed cylindrical hole with no centre point protruding.
Masonry Drill Bits — For Brick, Block, and Concrete
Standard Masonry Bits (for hammer drills) — Carbide tip bonded to a steel shank. For drilling through brick, block, mortar, and some soft concrete using a standard hammer drill. Available in 3–25mm with standard round or SDS-style shanks.
SDS-Plus Bits — The correct bit for SDS rotary hammer drills. The SDS-Plus shank locks into the rotary hammer's chuck and allows the bit to reciprocate with the hammer mechanism. Dramatically faster and more efficient in concrete and reinforced masonry than standard masonry bits in a hammer drill. Use 4–26mm SDS-Plus bits with SDS-Plus rotary hammers (the most common format).
SDS-Max Bits — For heavy-duty SDS-Max rotary hammers. Larger diameter and longer lengths for drilling 26mm+ holes in reinforced concrete and for sustained professional work.
Holesaws — For Large Diameter Holes
Holesaws cut annular circles — removing a disc rather than converting all material to waste. Available in diameters from 14mm to 152mm and beyond.
Bi-Metal Holesaws — The most versatile type. Cuts timber, plasterboard, MDF, copper pipe, conduit, and thin steel. One holesaw body works with a standard mandrel on any drill.
Carbide-Tipped Holesaws — For abrasive materials: fibre cement sheeting, ceramics, epoxy materials. Last many times longer than bi-metal in these applications.
Diamond Core Bits — For drilling through ceramic tile, porcelain, glass, and stone. Must be used wet — a water feed or damp sponge cools the diamond edge and removes slurry. Use at low speed with consistent light pressure.
Buying Tips
Buy quality bits — cheap bits are a false economy. A set of quality HSS-Co bits or a quality SDS-Plus bit will outlast a drawer full of budget equivalents and produce cleaner holes with less effort. Key brands at Toolup include Sutton Tools (Australian-made and excellent quality), Alpha, Milwaukee, and Makita.
For SDS bits, match the shank to your tool — SDS-Plus and SDS-Max are not interchangeable. Most professional rotary hammers use SDS-Plus; only the largest hammers use SDS-Max.
Free shipping on orders over $199 at Toolup. Trade pricing on drill bit sets and bulk orders — call (03) 5241 9555.