Drill Bits Explained: Choose for the Material, Hole & Machine
A drill bit is the cutting accessory fitted to a drill to make a hole in a material such as wood, metal or concrete.
The right bit depends on the material, the hole size and depth, and the machine you will use. This guide explains the main types, materials and fittings to help you choose.
Quick pick: start with the material
| Material | Bit to consider | What to check |
|---|---|---|
| Wood and wood-based boards | Wood drill bit, such as a brad-point bit | Hole diameter, depth and suitability for the board or timber |
| Steel and other metals | HSS twist drill bit | Exact metal, bit specification and recommended cutting conditions |
| Stainless steel | HSS-Co bit specified for stainless steel | Material suitability, speed and lubrication instructions |
| Brick, masonry or concrete | Masonry or concrete bit matched to the drill | Substrate, shank, operating mode and required hole depth |
| Glass or ceramic tile | Specialist glass or tile bit | Exact surface, hardness and drilling instructions |
Wood bits: choose for the hole
Brad-point bits have a centring point that helps position the hole accurately in wood. Choose the diameter and working length for the job, and check the stated suitability for timber, plywood or other boards.
For a larger opening, a different accessory may be appropriate.
Metal bits: HSS, cobalt and coatings
HSS means high-speed steel, a common material for metal twist drill bits. Select a bit explicitly suited to the metal you plan to drill.
HSS-Co is high-speed steel alloyed with cobalt. Bosch specifies this construction for bits designed for stainless steel and other demanding metal applications. It is not simply a surface coating.
TiN means titanium nitride, a coating used on some HSS bits to reduce friction and wear. A “titanium” description does not mean the whole bit is made from titanium. Check the product's material restrictions and cooling requirements rather than choosing by its gold colour.
Masonry and concrete: match the bit and drill
Masonry and concrete bits commonly use carbide cutting tips. Choose for the particular substrate and the machine's intended application, rather than treating all walls or stone as the same material.
Cylindrical-shank masonry bits and SDS accessories have different mounting requirements. Match the exact shank system to the tool, and follow the bit and machine instructions for hammer or rotary operation.
Glass and tile: identify the surface first
Soft ceramic, hard porcelain and glass need careful product selection. A bit specified for one is not automatically suitable for the others.
Use the manufacturer's specified rotary mode, speed and pressure. Cooling is product-dependent: some tile bits are designed for dry use, while others require a different method. Avoid applying one drilling recipe to every tile bit.
Will it fit your drill?
The shank is the end held by the machine. Choose for the chuck or tool holder fitted to your drill, not simply whether the drill is corded or cordless.
| Shank or fitting | Typical matching holder | What to check |
|---|---|---|
| Round or cylindrical | A three-jaw keyed or keyless drill chuck | The chuck's clamping range must accommodate the shank diameter. |
| Hexagonal | A compatible three-jaw chuck or specified hex holder | Confirm the shank size and retention system. Use in an impact driver only when the bit is expressly approved for it. |
| SDS-plus | An SDS-plus rotary-hammer holder | Look for the exact SDS-plus designation on the accessory and machine. |
| SDS-max | An SDS-max rotary-hammer holder | Match the SDS-max system; it is a different fitting from SDS-plus. |
SDS-plus and SDS-max are not directly interchangeable. Some machines support approved adapters, interchangeable chucks or multi-fitting holders; use only combinations and operating modes permitted by the machine manufacturer.
Check hole size, depth and operating mode
- Diameter: select the hole size required by the job. For fixings, follow the fixing manufacturer's specified drilling diameter.
- Working length: distinguish usable drilling length from overall bit length. The full length includes the portion held by the machine.
- Operating mode: wood and metal drilling normally use rotation without hammer action. Follow the specific instructions for masonry and specialist bits.
Single bits or a set?
A set is convenient for varied work; individual bits make sense when replacing a worn size or buying for a specific material. Compare the actual sizes and bit types included, not just the piece count.
Tell BOLD Industrial the material, required diameter and depth, and your drill model. These details help us narrow down suitable options and confirm specifications and availability.