Cutting plywood to size
Whether your sheet goods become sheathing or cabinetry, you need to know how to cut them properly
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.
A general-purpose blade with 24 teeth is what you need for cutting sheathing and framing lumber. For smoother cuts, a 40-tooth finish-cutting blade works best.
Set up, snap, and cut
Step 1: Mark the cutline. Support the panel on scrap lumber, and snap a line to mark where you need to cut.
Step 2: Adjust cutting depth. The blade should extend no more than 1/4 in. below the bottom of the panel.
Step 3: Follow the line. A good view of the blade, a two-handed grip, and a balanced stance ensure safety and accuracy.
To cut finish panels, you need a guide
Inexpensive aluminum straightedges are available in lengths of up to 8 ft. (Johnson Level & Tool Co.; www.johnsonlevel.com). 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.
A Homemade shooter board makes it easy
Assembled from two pieces of plywood, a shooter board combines a straightedge with an attached base that can be aligned right on your planned cutline. Simply clamp the shooter board to the panel, and you’re ready to rip. The base of the shooter board will reduce tearout, but it’s still a good practice to cut finish panels with the good side facing down.
To make a shooter board, you need a 4-ft. or 8-ft. length of 3/4-in. plywood (about 1 ft. wide) with a straight, smooth “factory” edge that can guide the baseplate of the saw. Start by ripping a 2-in.- to 3-in.-wide strip that includes the factory edge. Screw this guide piece to the base of the shooter board. Make sure that when the factory edge guides the baseplate of the saw, you’ll cut the base to its finished size.
Scribe and guide
Step 1: Cut before sawing. Scribing the cutline with a utility knife can help to reduce tearout when making finish cuts.
Step 2: Easy alignment. Use an offset board to align the straightedge the correct distance from the cutline. The width of the board should equal the distance from the edge of your saw’s baseplate to the blade.
Step 3: Make a guided cut. Running the saw’s baseplate against a straightedge ensures a straight cut.
Photos by: Chris Green