Cut big panels down to size
Wrestling with 4x8' panels in a small shop can be a losing battle. Here's a way to cut them before taking them into your shop. First make a straightedge using the factory-cut edge of a 10"-wide scrap of plywood or medium-density fiberboard. Next lay the panel on a sheet of rigid foam insulation at least 1" thick. Measure from the saw-base edge to the blade, and clamp your straightedge that distance from the cutline. Clamp the guide in place; set the blade cutting depth to penetrate 1⁄4 " into the foam insulation, and then make the cut, as shown.
—from the WOOD® shop