A short list beats a giant set
Drill bit catalogs are enormous, but a workshop gets by with a surprisingly short list. The goal is to cover three situations: general holes in wood and metal, clean holes in wood where appearance matters, and larger holes that a standard bit cannot reasonably make. Add masonry bits only if you work with brick or concrete.
Twist bits
The twist bit is the general-purpose workhorse: a spiral-fluted shaft with a conical point. A set covering small to medium sizes handles most jobs in wood, plastic and light metal. What varies is material and coating. High-speed steel bits are a common, affordable choice and handle wood and soft metals; coated versions, such as black oxide or titanium-based finishes, are often marketed as longer-lasting or better for metal. Cobalt alloy bits are typically chosen for tougher metals such as stainless steel. The details of bit material are worth a closer look if you drill a lot of hard metal.
Twist bits tend to wander when starting a hole in metal. A center punch dimple gives the tip a place to sit. For metal, use slow speed and cutting fluid or oil, and clear chips often. Keep the speed lower as the bit size increases. Good habits for drilling metal without ruining bits come down to slow speed, steady pressure and lubrication.
Brad point bits
Brad point bits have a sharp central spur and two outer spurs. The spur locates the hole accurately and the outer spurs shear the wood fibers, so the hole edge is cleaner than a twist bit leaves. They are a good choice for furniture, dowel holes and anything where the entry hole will be visible. They are designed for wood and wood products, not metal. Standard sizes are available individually or in sets; fractional sizes cover most needs.
Spade bits
Spade (or paddle) bits are flat and inexpensive, and they bore larger holes quickly, usually in rough work such as running wire through framing. They leave a rougher hole and can tear out on exit, so back the workpiece with scrap wood or drill from both sides. They need a firm grip because they can grab and twist the drill. Use a drill with enough power, keep both hands on the tool, and brace carefully.
Forstner bits
Forstner bits cut flat-bottomed holes with clean edges, which makes them the standard choice for hinge cups, shallow recesses, and holes that overlap or sit at the edge of a board. They work best in a drill press at lower speeds, where depth and alignment are easy to control, though they can be used in a hand drill with care. They are generally more expensive than spade bits, so a few common sizes are usually enough.
Auger bits and self-feed bits
Auger bits have a screw tip that pulls the bit through the wood and are commonly used for deep holes in timber. Self-feeding versions are for power drills, while older hand-brace augers are for brace-and-bit use. These are specialized, so add them only if your projects involve timber framing or deep boring. They also pull aggressively, so a drill with enough torque and a firm stance are essential.
Countersink and pilot bits
A combination countersink bit drills a pilot hole and a recess for a screw head in one go. A shop that builds with screws benefits from at least one, and the right pilot size depends on the screw and the wood. Preparing the hole first reduces splitting, especially near the end of a board.
Step bits
A step bit has a conical, stepped profile that enlarges holes in thin sheet metal one step at a time and deburrs as it goes. It is handy for electrical enclosures and panels. If you work with thin metal regularly, a step drill bit is worth considering.
Masonry bits
Carbide-tipped masonry bits drill into brick, block and concrete. They work best in a hammer drill setting, or with a rotary hammer for larger holes. Without hammering action, progress is slow and the bit overheats. Masonry dust is a respiratory hazard, so wear a suitable mask and eye protection. The basics of hammer drilling masonry cover the technique in more detail.
Hole saws
Hole saws cut large holes, such as for door hardware or recessed lights, and are sold as kits with interchangeable saws and an arbor. A kit is usually more practical than buying one at a time. Use low speed, back out regularly to clear chips, and clamp the work.
What a sensible starter set looks like
For many shops, this is enough:
- A set of twist bits in common fractional sizes.
- A set of brad point bits for wood.
- A few spade bits in larger sizes.
- One or two Forstner bits for hinges and recesses.
- A combination countersink bit.
- Masonry bits, only if needed.
Add specialty bits when a project calls for them. Buying a large pile of bits up front often means many sizes never get used.
Caring for bits
Dull bits cause burning, wandering and excess force. Check bits for dull edges, discoloration from heat and chipped tips. Some twist bits can be sharpened with a guide or small grinder, but cheap bits are often easier to replace. Store them in an indexed case so you can see what is missing, keep them dry to reduce rust, and wipe off resin or pitch after use.
Safety
Wear eye protection, clamp the workpiece rather than holding it by hand, and secure long hair and loose clothing. Remove the battery or unplug the drill before changing bits. If a bit binds, release the trigger and back it out; do not fight a stuck drill. Follow the manufacturer’s guidance on maximum speeds and bit sizes for your drill.