How to Use Forstner Bits

Conventional twist drill bits are center-guided: The first and deepest contact with the material is made by the sharp center-point of the bit. Forstner bits, however, are rim-guided. The sharp outside edge of the circular rim makes the primary cut and defines the circumference of the bored hole, while a machined cutting blade hollows out the interior. This creates a hole with an extremely clean margin and a very flat bottom. Because they do not require center-point contact with the wood, Forstner bits can drill angled or overlapped holes, and are particularly suitable for drilling into the end grain of wood without being diverted by the grain. They are substantially more expensive than standard bits and are more commonly used with a drill press. A few tips can help you get the most out of these useful tools.

Forstner drill bits

Instructions

- 1
  Handle with care. Forstner bits are precisely machined, delicately honed instruments, particularly the cutting edge around the rim. Keep the bits in a proper holder. Don't let them bang about loose in a tool box or drawer.
- 2
  Watch your speed. Forstner bits are speed-rated according to particular wood types. Learn the manufacturer's recommended drill speed for the bit and the wood and don't exceed it.
- 3
  Mount it in a hand drill for angled holes. Start at 90-degrees until the rim of the Forstner begins biting into the wood, then lean the drill over to the desired angle and keep the speed steady while applying pressure to penetrate to the correct depth.
- 4
  Create the slot in a mortise joint without a lot of chisel work by using a Forstner bit to drill overlapping holes. You can drill out a great deal of material quickly, then use the chisel merely to clean up the joint.
- 5
  Use a saw instead of a Forstner bit to make holes larger than four inches in diameter. Though one of the Forstner claims to fame is its ability to drill immaculately clean large holes, if you're on a budget, a jig saw is probably the better option. Forstner bits in that size range can easily exceed $150.
- 6
  Go over the edge. A Forstner is the only bit in existence that can drill a partial hole along the edge of a board. This is useful for mounting figure-eight style fasteners used in furniture manufacture.

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