Which Is the Best Type of Drill Bit to Buy for Metal & Wood?

Twist Bit

• Familiar to most do-it-yourself builders, twist bits consist of a cylindrical shaft that tapers at one end into a conical, finely pointed tip. Sharp-edged, helical channels run from the twist bit's base to just below its tapered tip. The twist bit's coils aid drilling and push waste toward the work material's surface. Standard twist bits are sharp enough to drill through common metals, such as aluminum and soft steel, and all types of wood. Inexpensive and readily available, twist bits are multipurpose drill bits suitable for both basic wood and metalworking projects. Twist bits range in diameter from less than 1/16 inch to roughly 1 inch.

Heavy-duty Metal Bits

• Whereas standard twist bits effectively drill through common metals, boring through hard or thick metals requires specialized drill bits. High-speed steel, carbide, titanium and cobalt twist bits resist overheating, cracking and breaking during prolonged metal drilling projects. Metals that typically require specialty drill bits include stainless steel and hardened steel. If you plan to repeatedly cut through hard metals, a heavy-duty metal drill bit might be the best choice for your tool kit.

Wood Auger and Boring Bits

• To precisely drill holes through thick wooden materials, such as wall studs and beams, carpenters often use specialty wood bits, particularly auger and boring bits. Whereas deep, corkscrew-like channels coil along the shaft of auger bits, boring bits consist of a set of short, sharp-edged cutting wings that protrude from the bit's head. Both auger and boring bits have screw tips that grip and steady the bit while starting holes. Additionally, auger and boring bits' unique designs allow them to push through wooden material. Auger and boring bits are often the best choice for projects that require a large amount of perfectly straight holes through thick wood, such as routing electrical cables and plumbing pipes.

Specialty Bits

• Sometimes a specialty bit is not only the best tool for the job but also the only tool for the job. Metal specialty bits include end mills and tapered bits that bore specially angled shafts or flat-bottomed holes. Machining applications frequently require special bits to create precise connections between metal components. Common specialty wood bits include countersink bits. Countersink bits not only drill a pilot hole for the screw but also create a precisely sized dimple, which accommodates the screw's head and allows it to rest beneath the wood's surface.