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How to Choose and Use Drill Bits

Ask This Old House general contractor Tom Silva explains the uses for different drill bits


  1. The most common drill bit is a twist bit, or HHS bit, which can drill a small, uniform hole in a wide variety of materials. The coating of the bit will help determine exactly what materials the drill bit can withstand.
  2. Spade bits are good for drilling out a large amount of material quickly, but they don’t leave behind the cleanest cut. They're best used for jobs like rough electrical.
  3. Forstner bits have a lot more control than a spade bit and leave a clean, even cut. Unlike with a spade bit, it can leave a flat bottom in the surface being cut, which is helpful if the hole isn’t going all the way through the material.
  4. A countersink bit is good for drilling holes to accept screws.
  5. Changing out the bits will depend on what kind of drill you have. If you have a drill with a keyless chuck, you can tighten and loosen the chuck to accept and release the end of the bit. In impact drivers, there’s only one standard-end drill bit that the driver will accept, but it can easily be popped in and out of place.

Tom discusses a variety of different drill bits that all serve specific purposes. In general, consider the size of the hole that needs to be drilled and what material the whole needs to be drilled into. This will help you determine which drill bit will work best for your project.

All the drill bits Tom demonstrated, include the HHS bit, masonry bit, spade bit, and forstner bit, can be found at home centers.