Cutting Plywood to Size
Tips from a professional carpenter can help you acquire this basic building skill.
Synopsis: Cutting 4×8 sheets of plywood down to size is a basic task that most carpenters take for granted, but it can be daunting if you’ve never done it. In this short article, a professional carpenter explains the process and offers some tricks (using the right blade and making a shooting board) for doing it fast and accurately.
Sheets of plywood first appeared on job sites a little more than 50 years ago. They quickly proved their value. These days, a huge variety of panels is manufactured for applications that run the gamut from rough sheathing to fine cabinetmaking.
Every trade has its own secrets for cutting panels down to size. Framers often nail up full sheets (or overlap one sheet onto another), then trim the excess in place. Cabinetmakers rely on heavy-duty tablesaws surrounded by infeed and outfeed tables.
The rest of us just need a professional-grade circular saw, a stable cutting platform, and a good straightedge for precise cuts.
Sheathing is cut freehand
To prevent the blade from becoming pinched in the sawkerf—the primary cause of kickback—place a few 4-ft. lengths of scrap lumber between the panel you’re about to cut and the underlying sheets. Measure for the cut you need to make, and mark the cutline by snapping a chalkline. Secure the panel with a pair of Quik-Grip clamps. Then set the circular saw’s cutting depth.
Drape the saw cord over your shoulder to prevent the cord from catching on the edge of the panel, and cut along the line with both of your hands controlling the saw. To prevent kickback, maintain a balanced stance, and don’t force the cut. If you start to stray from the chalkline, don’t try to twist the saw back toward the line. Instead, turn off the circular saw, wait for the blade to stop spinning, and back up to the location where your cut was true. With the blade centered in the kerf, start to cut again. You’ll keep it straight this time.
To cut finish panels, you need a guide
Inexpensive aluminium straightedges are available in lengths of up to 8 ft. To prevent tearout when you’re cutting across the grain, scribe the cutline with a knife or an awl. Then offset the straightedge to allow for the distance between the sawblade and the edge of the baseplate. Secure the straightedge with some heavy-duty spring clamps; then make a guided cut.
From Fine Homebuilding #166