iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
A drill supplies rotation; the bit does the cutting. If the bit’s tip, geometry, diameter, shank or operating mode does not suit the workpiece, even a powerful drill may spin without making useful progress. Bosch’s DIY guide puts the decision in three parts: material, hole type and hole size (depth and diameter).
Choose the workpiece first, then the hole geometry, speed, shank and drill mode. That sequence prevents most stalled bits, scorched edges, wandering holes and damaged chucks.
Choose the bit by material
| Workpiece | Best starting bit | What to know |
|---|---|---|
| Softwood, hardwood, plywood or MDF | Wood twist or brad-point bit | A brad point centers the bit and its tapered geometry helps reduce tearing. It is especially useful for accurate pilot holes. |
| Large or deep holes in wood | Spade, auger or Forstner bit | Spade bits cut quickly but leave a rougher opening. Augers pull themselves through deep stock. Forstner bits produce clean, flat-bottomed blind holes. |
| Mild steel, aluminum, copper or brass | HSS metal twist bit | Use cutting fluid and avoid excessive speed or pressure, which can overheat the cutting edge. |
| Stainless steel and harder alloys | Cobalt HSS bit | Cobalt’s heat and abrasion resistance is intended for difficult metals. It still requires controlled speed, pressure and cooling. |
| Concrete, brick or natural stone | Carbide-tipped masonry bit | Use hammer or rotary-hammer action when the bit and drill permit it. Confirm whether the shank is ordinary round/hex or SDS before buying. |
| Ceramic or porcelain tile | Dedicated carbide or diamond-ground tile bit | Start slowly with moderate pressure to establish the hole, then reduce pressure. Masking tape over the mark can help prevent skating. |
| Thin sheet metal or plastic in several diameters | Step bit | One bit covers a range of sizes—Bosch describes common versions as roughly 4–20 mm. Run slowly enough to limit heat. |
| Large circular openings in wood, plastic, drywall or thin metal | Hole saw | A mandrel-mounted cup and pilot bit cut larger round openings in relatively soft materials. |
Specialized bits generally outperform an all-purpose bit when a material-specific design is available. A general-purpose HSS set can cover routine metal and drilling tasks, but it is not a substitute for masonry, tile, cobalt or woodworking geometries.
The Tool Desk
Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Let the hole decide the geometry
Diameter and depth
Most common drill bits fall in the 1–20 mm range, according to Bosch. Select the diameter required by the fastener, fitting or cable—not the diameter that happens to be in the case. For a through-hole, use a bit longer than the material is thick so the flutes can clear chips and the tip can emerge cleanly.
#1 Best Overall
- 135 Degree Split point tip design to help reduce walking
- High Speed Steel to be used in plastic, wood, and metal
- Tapered web design for extreme durability and resisting breakage
- Black and gold coating to help prevent rust and wear
- 3-Flats shank to reduce spin-out in the chuck on sizes larger than 3/16-in
Through-holes versus blind holes
Use a brad point for a controlled entry in wood, an auger when chip removal and depth matter, and a Forstner bit when the bottom must be flat. A spade bit is the fast, economical option when the back face will not be visible or a rougher edge is acceptable.
Large openings
Switch to a hole saw when the opening is much larger than a normal twist bit can reasonably make. The pilot bit keeps the cup centered; clear chips periodically rather than forcing a stalled saw.
Rank #2
- 100-piece drill and driver multi-bit set; ideal for metal, wood, plastic, masonry, and hole saws
- Includes 52 bits, 8 nut sockets, a magnetic bit holder, 4 hole saws, and more (scroll down the page for a full list of included pieces)
- Made of durable, wear-resistant alloy steel with quenching treatment
- Sturdy plastic case provides designated storage space and easy transport
Set speed, pressure and cooling together
- Small bit, soft material: higher speed is usually appropriate.
- Large bit or hard material: lower speed reduces heat and cutting load.
- Metal: use cutting fluid, moderate pressure and periodic withdrawal to cool the tip and clear swarf.
- Tile: begin slowly with moderate pressure, then lighten pressure after the bit has established a track.
- Wood: let the cutting edges remove chips; excessive force can tear fibers or split the workpiece.
Bosch’s practical rule is small bit/high speed, large bit/low speed, soft material/high speed and hard material/low speed. The bit maker’s stated range takes priority when it differs.
Match the shank and drill mode
Shank and chuck compatibility
Round shanks fit common keyed and keyless chucks. Hex shanks resist slipping and make quick changes easier. SDS shanks require a compatible rotary hammer; they are not interchangeable with an ordinary three-jaw chuck. Check the drill’s chuck capacity and the bit’s shank specification before starting.
Rank #3
- Titanium Nitride Coating Pilot Point for Longer Life
- Starts on contact for cleaner holes
- No spin shanks
- Tapered web provides greater durability to reduce breaking
- Includes sizes from 1/16-inch to 1/2-inch in a plastic tough case
Rotary versus hammer action
Ordinary wood and metal drilling uses rotary mode unless the manufacturer says otherwise. Carbide masonry bits are commonly paired with hammer or rotary-hammer action because the impact helps fracture concrete, brick and stone. Hammering on a bit not designed for it can damage the bit, workpiece or drill.
A reliable drilling procedure
- Identify the workpiece. Remove paint, cladding or a loose surface layer if it hides the material you must cut.
- Define the hole. Record the diameter, required depth, whether it is through or blind, and how clean the edge must be.
- Select the bit family. Use the material table, then choose twist, brad-point, spade, auger, Forstner, step or hole-saw geometry as appropriate.
- Verify the shank. Confirm round, hex or SDS compatibility and that the bit fits the chuck capacity.
- Set the drill. Choose rotary or hammer mode and start at a speed suited to diameter and hardness.
- Secure and mark the work. Clamp the stock where possible. On tile, tape can reduce skating; on metal, a small center mark helps the tip start.
- Start square. Use light initial pressure until the cutting edges establish a track, then maintain steady feed.
- Clear and cool. Withdraw periodically in deep holes. Apply cutting fluid on metal and stop if the tip discolors or the workpiece overheats.
- Finish deliberately. Reduce pressure as the bit breaks through to limit splintering, blowout or chipped tile.
Why a bit spins but barely cuts
- Wrong cutting tip: a wood bit on metal, a general twist bit on masonry, or a metal bit on tile will have the wrong edge geometry.
- Speed is too high: heat softens or dulls metal edges and can glaze some materials.
- Pressure is too low or too high: insufficient feed rubs instead of cuts; excessive force stalls the motor, bends the bit or breaks the tip.
- Flutes are packed: chips cannot escape, so withdraw and clear them.
- Shank is slipping: reseat and tighten a round shank, or use a suitable hex/SDS system.
- Mode is wrong: masonry often needs hammer action, while hammering on wood or metal is normally counterproductive.
- The bit is dull or overheated: replace it rather than compensating with more force.
When one bit is not enough
Buy a single bit when the diameter and material are unusual or the job is one-off. A set is practical when you need several diameters in the same material: brad-point and Forstner sets for woodworking, cobalt HSS sets for stainless and hard alloys, carbide-tipped masonry sets for concrete and brick, or step-bit sets for sheet metal and plastic. Sets do not make a mismatched bit suitable; they only expand the correctly chosen family.
Rank #4
- CORROSION RESISTANT: Gold oxide coated drill bit promotes longer life
- PRECISE HOLE PLACEMENT: Split Point of the drill bits for wood, metal or plastic provides precise hole placement and clean, burr-free holes
- CONVENIENCE: Metal Carrying Case for compact and durable storage of the drill bits
- Plastic carrying case for compact and durable storage
Safety and setup checks
- Clamp the work and keep hands clear of the exit side.
- Wear eye protection; masonry and metal produce chips, and tile can eject sharp fragments.
- Check for concealed wiring, plumbing and structural reinforcement before drilling walls or slabs.
- Stop when a bit binds, smokes, discolors or vibrates unusually. Let it cool, inspect the chuck and reassess material, speed and mode.
The central fix is simple: treat the drill as the power source and the bit as the cutting tool. Material, hole geometry, speed, cooling and compatibility must agree before motor power matters.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Quick Recap
Best Value
- DEWALT 21-pack black oxide twist drill bit set is ideal for general-purpose drilling materials like metal, hardwood, softwood, PVC and fiberglass
- Parabolic flute design increases chip ejection in metal and wood drilling applications
- Black oxide coating helps resist corrosion and increase durability, so your drill bits last longer
- 135° Split-point tips drill on contact and prevents walking on the hard surface you’re working on
- 31° Helix reduces over aggressiveness of true parabolic flute, making it ideal for drilling deep holes
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
