In this video, This Old House general contractor Tom Silva shows host Kevin O'Connor how to make clean, straight cuts.
1. Always wear safety glasses when using a portable circular saw to protect your eyes from flying sawdust.
2. With the saw unplugged, check the spring-loaded lower blade guard to ensure that it rotates back and retracts smoothly.
3. There are two basic types of circular saws: gear-driven worm-drive and direct-drive sidewinder.
4. Sidewinder saws are available with the blade mounted on left or right side of the saw.
5. Be sure to use sharp blades for the smoothest, safest cuts. Carbide-tipped, thin-kerf blades are ideal for making crosscuts and rip cuts in wood.
6. Diamond-impregnated blades can cut stone, tile and other masonry materials.
7. Fine-tooth plywood blades are designed for producing splinter-free cuts in plywood and other veneer-topped sheets goods.
8. Two types of carborundum blades are available: Silicone-carbide blades for cutting masonry, and aluminum-oxide blades for cutting metal.
9. To make a crosscut, first mark the cut line onto the board, then align the blade with the line. Be sure the saw blade isn't touching the board.
10. Slide a layout square up against saw shoe, squeeze the trigger and make the cut by guiding the saw along the edge of the square.
11. Make a rip cut by first marking a cut line at each end of the board. Then measure the distance from saw blade to edge of saw shoe. This is the offset dimension.
12. Measure from the cut line the distance of the offset dimension and draw a line.
13. Clamp in place a straightedge board or rip of plywood; place the straightedge on the offset marks, not the cut line.
14. Adjust depth of cut to ⅛ inch deeper than the thickness of the workpiece you're cutting.
15. Butt saw shoe against straightedge and make the cut.