Drill Large Holes in Wood With Ease

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Drilling precise, large-diameter holes in a fine woodworking project can be challenging if you have to do it with a handheld power drill or cordless drill as opposed to using a more precise drill press. Since the throat on the chuck of a handheld drill is smaller (typically 1/2-inch or less) than the chuck on the drill press, the diameter of twist bits that one can use is smaller. Additionally, when drilling with Forstner bits, the drill press is much easier (and safer choice) for powering the drill bit.

Auger bits (such as these Bosch NailKiller Bits can be a bit of overkill unless you are drilling through some deep stock (not to mention that auger bits take a good bit of horsepower and manhandling to use, and leave a rough cut hole behind). Hole saws can get the job done, but they're slow and removing the plugs from the bit can be a challenge.

So, for normal drilling of holes up to 1-1/2 inch in diameter, what would be a good choice?

Spade Drill Bits

Also commonly known as paddle bits, these flat bits are commonly used by tradesmen such as electricians and plumbers for drilling holes in studs in walls (to run wiring or pipes through the walls), but they also have a place in the woodshop for drilling on fine woodworking projects.

Spade drill bits are basically flat bits with a pilot point attached to a 1/4-inch diameter shank that can be used in both regularly-chucked drills and quick-chuck impact drivers. Each edge of the flattened portion of the bit is sharpened, and the bottom corners of the sharpened area occasionally have a pointed tip, depending on the style and brand of the spade drill bit. As the bit is turned by the drill motor, these two sharpened edges will dig into the wood stock around the center pilot point, shaving wood out of the hole in a corkscrew-like manner. If the cutting edges of the bit are particularly sharp, long shavings are sometimes produced by the drilling action.

To use a spade drill bit, mark the center point of the hole to be drilled on the wood, and install the shank of the bit into the drill. Align the point of the pilot tip of the spade drill bit with the mark on the wood, and adjust the angle of the handheld drill so that the shank of the bit is square to the surface of the wood.

(Of course, if you're using a drill press, the bit's angle should already be square to the surface of the wood, unless your drill table is not square to the motor).

Good to Know

Depress the trigger of your drill slightly to engage the motor and turn the bit slowly. Hold the drill as still as possible so that the pilot point stays aligned with the mark on the wood. Because pilot tips can often "walk" away from the intended center point of the hole, some woodworkers will pre-drill the pilot hole using a small-diameter twist drill bit that is less likely to walk, and then proceed with the spade drill bit's pilot tip into the pre-drilled pilot hole.

Once the pilot tip is in place and engaged with the wood, increase the speed and proceed to drill the large diameter hole with the spade drill bit. Continue drilling until you reach the opposite side of the wood and the bit pokes out through the completed hole. Slow the speed of the motor, and pull the drill bit out of the completed hole.

One common issue with spade drill bits is that they tend to "blow out" the back side of the holeĀ if there isn't another piece of wood stock on the back side of the wood being drilled. This blow out can be quite unsightly on a fine woodworking project. There are a few methods to combat this blow out discussed in another article called How to Drill Clean Holes.