Equipped with the proper bits, a 3/8 inch portable power drill can make holes in wood, metal, masonry, ceramic, plastic-even glass-and do many other jobs as well. For heavy duty work, such as drilling through steel beams, look for a 1/2-inch drill with a shoulder brace. (The size refers to the opening of the chuck and also reflects the power and weight of the unit.) Drills with variable speed and reverse drive are costlier than those without, but are well worth the money.
High-speed steel twist bits are good for holes up to 1/2 inch in diameter in wood, metal, and most plastics. For larger holes in wood, use a spade bit (to 11/2 inches), an expansive bit, or a hole saw. For drilling into concrete, brick, or stone, use a masonry bit with a carbide tip. Special carbide tipped bits are also needed for glass.
Drilling straight holes
First make sure that the piece you are working on is secure: clamp a board in a vise, wedge a door in place, and so forth. If possible, position the work so that you are drilling straight down or horizontally.
Mark the center of the hole with a center punch. Position yourself so that the bit enters at the proper angle and you can maintain steady pressure. Place the bit against the center point and start drilling slowly, speeding up after the bit has penetrated.
You can usually keep the drill fairly straight with the help of a try square or a combination square. If the precise angle is important, use a drill guide. Commercial guides are available that adjust to any angle, or you can make your own guide from a block of wood.
If you are drilling into metal, stop from time to time and apply a drop of light oil to the work. With masonry and plastic, keep the speed slow to prevent overheating.
To prevent wood from splintering where the bit emerges, clamp a piece of scrap behind the workpiece and drill into it. Or stop drilling when the tip of the bit emerges, then turn the piece and drill from the other side.
To drill a hole of a given depth (in making a mortise, for example), wrap a strip of masking tape around the bit. Drill until the tape touches the surface of the material. Hand-operated drills When electricity is not available, use a twist drill (also called an egg beater) for light jobs; for heavy work, use a brace and bit. High-speed steel bits work in a twist drill. A brace requires its own bits.