In this video, This Old House general contractor Tom Silva shows host Kevin O’Connor demonstrates the basic parts of a circular saw and how to make clean, straight cuts.
Steps:
- Always wear safety glasses when using a portable circular saw to protect your eyes from flying sawdust.
- With the saw unplugged, check the spring-loaded lower blade guard to ensure that it rotates back and retracts smoothly.
- There are two basic types of circular saws: gear-driven worm-drive and direct-drive sidewinder.
- Sidewinder saws are available with the blade mounted on left or right side of the saw.
- 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.
- Diamond-impregnated blades can cut stone, tile and other masonry materials.
- Fine-tooth plywood blades are designed for producing splinter-free cuts in plywood and other veneer-topped sheets goods.
- Two types of carborundum blades are available: Silicone-carbide blades for cutting masonry, and aluminum-oxide blades for cutting metal.
- 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.
- 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.
- 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.
- Measure from the cut line the distance of the offset dimension and draw a line.
- Clamp in place a straightedge board or rip off plywood; place the straightedge on the offset marks, not the cut line.
- Adjust depth of cut to ⅛ inch deeper than the thickness of the workpiece you’re cutting.
- Butt saw shoe against straightedge and make the cut.
Norm Abram, This Old House master carpenter, explains the key difference between the two types: “A worm-drive saw has a pair of gears between the motor and the blade, making it almost unstoppable. In a sidewinder, the motor turns the blade directly, so it will slow down if pushed too hard.” Despite the worm drive’s power advantage, Norm says he generally uses a sidewinder, mostly because it’s the saw he grew up with.
Pro Tip: Tommy Silva, This Old House general contractor, recommends making a circular saw your first purchase: “If someone is gonna buy a saw, this is the first saw that you should buy because you can do just about anything with them.”
When choosing a blade, scrutinize the teeth: their grind pattern and number determine which kind of cutting best suits them. Blades with fewer teeth (20 to 40) are good for heavy ripping, while those with more teeth (50 to 80) promise clean, precise crosscuts. Common grind patterns include Flat Top (FT) for ripping with the grain, Alternate Top Bevel (ATB) for smooth crosscuts and miters, and Triple Chip Grind (TCG) for slicing particleboard and plastics.
Pro Tip: Norm Abram, This Old House master carpenter, emphasizes marking the waste side of the board first: “Mark the side of the material that will become waste, then line up the blade to just leave the pencil line on the keep side.” This ensures your finished piece stays true to your measurements.
