Step-by-Step

Well-supported work results in clean, safe cuts. If the scrap piece is short, support the board on the nonscrap side. If the scrap is long, it could bind the blade or splinter as it falls away at the end of the cut. To achieve a neat cut and avoid saw kickback, support the lumber in four places. Even with such precautions, you may want to make two cuts: one to cut the work roughly to size, the other for the finish cut.

To square a blade, hold a speed square against the blade and adjust it. (Be sure to position the square between the teeth.) To test if your blade is square to the baseplate, crosscut a piece of 2x lumber. Flip the piece over and press cut edge against cut edge. If you see a gap at the top or the bottom, the blade is not square.

Once you have drawn an accurate cutoff line and have properly supported the board, position the saw blade to the scrap side of the line. The teeth on most circular saw blades are offset in an alternating pattern, half to the left and half to the right. When clamping a guide, align a tooth that points toward the cutoff line.

With practice, you will learn to cut accurately without using a guide. But for cuts that have to be precise, use a guide. For 90-degree cuts, a speed square works well because it's easy to hold stable. Align the blade, then slide the square into position against the saw's baseplate. Grab the board along with the square, so the square won't slip out of position.

With care, you can improvise a saw guide that will be as accurate as a miter box. Set a T-bevel to the desired angle (see Using Special Marking Techniques, Related Projects) and transfer the angle to the board. Select a straight piece of 1x and clamp it along the cutting line as a saw guide. To offset the guide correctly, measure the distance between the blade and the edge of the saw's baseplate and clamp the guide that distance from the cut line. It may take some experimenting before you get this correct. Be sure to align the blade to the correct side of the line. You can use the same principle for long rip cuts. Clamp a straightedg--the factory edge of a 1x or a drywall square--onto the material, setting it back from the cut line to allow for the width of the saw's baseplate.

Cut sheet goods with a carbide-tipped combination blade or a plywood-cutting blade for a smoother cut. It is important to support the sheet properly, or the blade will bind. You can do this by setting four 2x support pieces on the floor, a table, or a pair of sawhorses. Arrange two support pieces on either side of the cut line so that when the cut is complete, both pieces of the sheet are stable.

Use a guide to make a straight, long cut. Get a straightedge that is as long as the material you are cutting--a straight 1x4 or the factory edge of a piece of plywood. Measure the distance from the edge of the saw's baseplate to the blade and clamp the guide that distance away from the cut line. Set the saw in place and check alignment with the cut line. Clamp the opposite end of the guide the same distance from the edge.

Use a plunge cut, also called a pocket cut, to make a hole or slit in the middle of a board or sheet. Set the blade to the correct depth. Retract the safety guard and tilt the saw forward, setting the front of the baseplate on your work. Start the saw and lower it slowly into the cut line until the base rests on the stock. Complete the cut. Note: Because you will be exposing the blade, any twist could result in a dangerous kickback. Be careful.