With holes in wood,
bit selection makes the difference

Making holes in wood can be a snap . . . or an agonizing process. To take your hole making from an odious chore to a satisfactory process, industry experts agree successful hole making is a matter of selecting the right equipment and keeping a sharp edge on your bits. For safety’s sake, the experts agree you should wear protective glasses, gloves and other recommended safety gear whenever making holes.

Wood work
Drill bits for making holes in wood continue to evolve. The most common bits and a few innovations manufacturers now offer include:

• Twist bits: For small holes, generally from 1/8" to 1/2" in diameter, twist bits work well. Applications include making pilot holes for screws or holes for small bolts. They can also be used in metal or plastic.

• Spade bits: These are the lowest-cost bits that can be used to make holes in wood. They can make holes from 1/4" to 1 1/2" for rough work, such as running conduit through joists and studs.

“While spade bits are acceptable on occasion,” says Ralph Cox, president of Magna Primark, “You will get neater holes faster with a more expensive bit that will also last longer. Spade bits can be hard on the user. They can grab in the hole and jerk the drill. The wood splinters if you don’t finish the hole from the other side when the tip breaks through.”

Milwaukee Electric Tool offers a wood bit that it says can cut a smooth, finished hole three times faster than a spade bit. The PathFinder bit has six cutting edges that allows the bit to bore, counter-core and cut sideways. Its slender shaft design allows the user to even cut a 90-degree hole.

Bosch Power Tools and Accessories will introduce a faster bit mid-summer, 2003. “We’ve added what we call a RapidFeed tip that’s threaded like a wood screw and literally pulls the bit through the wood,” says Doug Collins, group marketing manager. “In addition, we’ve increased the cutting angle to keep up with the speed of the threaded tip. And because the RapidFeed pulls itself through wood, it requires less pressure, making overhead applications easy on the arms.”

• Auger bits: These work better for stud work and large-diameter holes. They start easily, jerk less than other styles as the hole gets cut, and move the material out of the hole efficiently. Workers doing electrical and plumbing work prefer them because they can sink a clean hole quickly.

Collins points out, “Auger bits are more expensive than twist or spade bits, but they deliver a very smooth bore hole. They’re also typically longer than other wood-boring bits. They’re good for use in buildings with exposed beams or where clean holes in large timber are important.”

Cox says Magna Primark offers a Woodeater bit that is a cross between a spade bit and an auger bit. It self-feeds aggressively and, like the auger bit, cleans material out of the hole so the user can plunge through the material.

• Forstner or brad-point bits: For a clean-looking hole, a brad point bit or a forstner bit will cut through wood and emerge with little or no chipping or wood splintering. They are preferred among finish carpenters and cabinet hangers.

“Forstner bits are used for large-diameter applications and brad point bits for smaller holes,” Collins says. “While brad points typically cost more than a twist drill, forstner bits can be very expensive.”

• Holes saws: For holes larger than 9/16" and up to 6", the experts suggest hole saws. These tools produce a relatively clean but shallow hole in wood, metal, plastic and drywall. Typical applications are holes for pipe runs, vents or multiple electrical cables through walls, floors and joists. They come in carbon steel for wood and bi-metal for wood and metal.

“Carbide-tipped hole saws, because of their heat and wear resistance, are well-suited for pressed woods that tend to be more abrasive due to the glues used in their construction,” explains Dave Byrley, director of new product development and quality at The M. K. Morse Co.

“Another very popular application for hole saws is in lock installation on doors,” Collins says. “The doors are prepped with a 2-1/8" face bore for the lock. The edge bore is done with either a hole saw or a spade bit.”

Speed is the biggest enemy of hole saws. Check the manufacturer’s directions for the correct running speed. Hole saw quality also can affect speed and hole quality. Look for models with variable-pitched teeth. They’re more user-friendly and last as much as 45 percent longer than hole saws with straight-pitched teeth.

Some larger hole saws are available today. M. K. Morse has developed a 6.5"-diameter hole saw. Instead of teeth, it has carbide grit that makes a clean cut in drywall or acoustic tile.

Collins says Bosch recently introduced a new hole saw concept. “The Power Change is the first true fast-change hole saw system on the market,” he claims. “By purchasing one mandrel, the user can manage 60 different sizes of hole saws. Conventional thread-on mandrels often seize on the hole saw and can’t be removed, but not the Power Change. We’ve added a hex-shaped nut that snaps into the mandrel. This maintains a positive connection with no wobble,” he says.

Published in the May/June 2003 issue of Contractor Tools and Supplies magazine.

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