A portable electric drill can make clean, precisely angled holes in a variety of materials. The first step is to use the proper drill bit.
Specialized bits for electric drills are available for metal, acrylic plastic, masonry and concrete, glass and tile as well as for rough and precise work on wood. Check with your hardware store to find the right bit for a specific job.
Wear safety goggles when using a drill. A full face shield is safest when drilling ceramic tile, masonry, concrete or other hard materials.
Prepare Piece to Be Drilled
To drill a straight hole, first make sure that the piece you are working on is secure. Clamp a board or wedge a door in place. If possible, position the work piece so that you are drilling straight down on it or are holding the drill horizontal to it.
You can drill a fairly straight hole with the help of a try square or a combination square. Set the square upright and keep the drill parallel to its vertical edge as you drill straight down. If the precise angle of the hole is important, use a drill guide. You can buy guides that mount on the drill and hold it at the desired angle while you drill. A guide also allows you to control the depth of a hole.
Holding the Drill
To increase precision and reduce drill bit breakage, hold an electric drill with your palm high up on the handle, directly behind the chuck. Extend your index finger along the body of the drill and use your second or third finger to operate the trigger.
Position yourself so that you can maintain steady pressure as a bit enters at the proper angle. Place the bit against the center point, start drilling slowly, then speed up after the bit has penetrated.
* Before using drill bits, lubricate them with silicone spray. The bits will break less easily and stay sharp longer.
* Punch an indentation where the hole's center will be with a center punch, awl or nail to help keep the drill bit from wandering.
* If you want to drill a hole to a given depth, wrap a piece of masking tape around the bit at the depth you want. Then drill until the tape touches the surface of the material. You can also use a cork to gauge depth. Drill an undersized hole through the center of the cork so that it fits snugly on the bit and doesn't move when it reaches the material.
Working With Specific Materials
* When drilling smooth sheet metal, ceramic tile or glass, prevent the bit from wandering by sticking an "X" of masking tape over the spot you're drilling.
* When drilling thin metal, apply several drops of light household or motor oil to the bit and hole as you work. To drill thick metal or steel, make a well with modeling clay to contain the oil. Drill slowly and exert firm pressure. Slow the speed if the bit squeaks and pause if it turns blue or smoke appears. Lift the bit to clear waste and add oil.
* To avoid splintering wood as the bit breaks through the back, place a block of scrap wood under the piece being drilled. Or, stop drilling when the tip of the bit emerges, then turn the work over and finish the hole from the opposite side.
* To drill in tubing, clamp the tubing in V-blocks or a padded vise. Insert a dowel in thin tubes to reinforce walls and guide the bit straight through.
* When drilling acrylic plastic, use a low speed. Twist bits for metal will work, but for best results, buy a specially ground twist bit from a plastic supplier. Support the work with scrap wood and apply light pressure.