A drill is only the motor and chuck. The bit’s cutting geometry, material and shank determine whether that motor can make a clean hole. Select the bit for the workpiece first, then match its diameter, depth, speed, cooling and chuck connection.
Start with the material, not the drill
Using a powerful drill with the wrong bit can produce a spinning tip, dust instead of a cut, excessive heat or a ragged hole. Bosch’s guidance is straightforward: the required drill depends on the material, the type of hole and the hole’s depth and diameter. A material-specific bit normally outperforms a general-purpose bit when the correct option is available.
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| Workpiece | Best starting bit | Important operating notes |
|---|---|---|
| Softwood, hardwood, plywood or MDF | Wood twist or brad-point bit | A centering point positions the bit; tapered geometry helps reduce tearing. |
| 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 wood. Forstners make clean, flat-bottomed blind holes. |
| Mild steel, aluminium, copper or brass | High-speed-steel (HSS) metal twist bit | Use cutting fluid and avoid excessive speed or pressure, which can overheat the tip. |
| Stainless steel or harder alloys | Cobalt HSS bit | Cobalt’s heat and abrasion resistance is suited to harder metals. |
| Concrete, brick or natural stone | Carbide-tipped masonry bit | Use hammer or rotary-hammer action where appropriate, and verify chuck or SDS compatibility. |
| Ceramic or porcelain tile | Dedicated carbide or diamond-ground tile bit | Begin slowly with moderate pressure to establish the hole, then reduce pressure. Tape over the spot can limit skating. |
| Thin sheet metal or plastic in several diameters | Step bit | Typical step ranges cover roughly 4–20 mm. Use slower speeds to control heat. |
| Large circular openings in wood, plastic, drywall or thin metal | Hole saw | A mandrel-mounted cup uses a pilot bit to keep the cut centered. |
A general-purpose bit set is convenient for occasional mixed-material work, but it cannot replace a dedicated wood, metal, masonry or tile design when finish and reliability matter.
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Diameter and depth
Most common drill bits fall in the 1–20 mm range. Select the diameter required by the fastener, fitting or cable rather than enlarging a hole afterward. For a through-hole, choose a bit longer than the material thickness so the flutes can clear debris and the tip can exit without the chuck contacting the workpiece.
#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
Through-holes prioritize chip evacuation and sufficient flute length. Blind holes stop at a controlled depth; Forstner bits are useful in wood when a flat bottom and clean shoulder are required. A depth stop, tape flag or marked shank helps prevent drilling too far.
Finish and edge quality
Brad-point bits help start accurately in wood and reduce wandering. Spade bits are efficient for rough utility holes but can tear fibers at the exit. For a cleaner wood opening, support the back of the workpiece or drill from both sides when practical. Hole saws are appropriate when the opening is much larger than a conventional twist bit can make.
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
Use the diameter-and-hardness rule
Run small bits faster and large bits slower. Soft materials generally tolerate higher speed; hard materials require lower speed. A large bit at high speed generates heat quickly, while a tiny bit pressed too hard can snap or wander.
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Apply cutting fluid to HSS and cobalt bits when drilling metal, withdraw the bit periodically to clear chips and let the tip cool, and follow the bit maker’s operating guidance. A squealing bit, discoloration or smoke indicates that speed or pressure is too high, lubrication is inadequate, or the bit is dull.
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
Clear chips instead of forcing the cut
Flutes need room to carry material out of the hole. On deep wood or metal holes, back the bit out intermittently. Forcing a packed flute increases friction and can seize the bit even when the drill has ample power.
Match the shank and drill mode
Shank and chuck fit
- Round shanks: fit common keyed and keyless chucks.
- Hex shanks: improve grip and allow quick changes in compatible chucks or drivers.
- SDS shanks: require a compatible rotary hammer; a standard three-jaw chuck cannot safely substitute for an SDS holder.
Before drilling, insert the shank fully, tighten the chuck evenly and confirm that the bit runs true. An incompatible or poorly clamped shank can slip, wobble or damage the chuck.
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
Choose rotary or hammer action
Use ordinary rotary mode for wood and metal unless the tool or bit maker specifies otherwise. Masonry bits are commonly paired with hammer or rotary-hammer action because the percussion helps fracture concrete, brick and stone. Hammer action on wood, metal or tile can damage the workpiece and the bit.
Material-specific methods
Wood
- Mark the center and clamp the workpiece.
- Use a brad-point or wood twist bit for ordinary holes; choose an auger, spade or Forstner design for the required diameter, depth and finish.
- Start at a controlled speed, keep the bit square and reduce tear-out by backing the workpiece or easing pressure as the tip exits.
Metal
- Punch a small center mark so the tip does not skate.
- Use HSS for common mild metals and cobalt HSS for stainless or harder alloys.
- Run at a lower speed for larger diameters or harder stock, apply cutting fluid and withdraw periodically to clear chips.
Concrete, brick and stone
- Confirm that the carbide-tipped masonry bit matches the hole diameter and that its shank fits the drill.
- Use hammer or rotary-hammer mode when the tool and material permit it.
- Clear dust regularly and stop if the bit overheats or the hole begins to wander.
Tile
- Mark the location and apply tape if the surface is slippery.
- Use a dedicated carbide or diamond-ground tile bit at slow speed with moderate pressure until the surface is established.
- Lighten pressure after the bit has started and avoid hammer action, which can crack tile.
Why a bit spins but barely cuts
- Wrong cutting tip: a wood or metal bit will not efficiently cut masonry, and a masonry bit is unsuitable for clean metal work.
- Incorrect mode: masonry may need hammer action, while hammering can damage tile, wood and metal.
- Speed is too high: heat softens or dulls metal-cutting edges and can damage tile.
- Pressure is too low or too high: insufficient pressure lets a bit rub; excessive pressure stalls the flutes, overheats the tip or breaks a small bit.
- Bit is dull: replace or properly sharpen it rather than compensating with more force.
- Chuck mismatch or slip: a loose or incompatible shank prevents the cutting edges from staying engaged.
- Debris is trapped: packed flutes cannot evacuate chips, so withdraw and clear the hole.
A quick pre-drilling checklist
- Identify the workpiece and select a material-specific bit.
- Confirm diameter, depth, hole type and required edge finish.
- Check that the bit is longer than the material for a through-hole.
- Match the shank to the chuck, including SDS requirements.
- Set rotary or hammer mode correctly.
- Choose speed based on bit diameter and material hardness.
- Prepare cutting fluid for metal and a way to clear chips or dust.
- Clamp the workpiece, mark the center and wear suitable eye protection.
The expensive drill is rarely the limiting component. Once the bit matches the material and hole, the correct speed, mode, cooling and chuck fit let the motor do the work it was designed to do.
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
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