A new angle on sawing panels
Try this strategy for making clean, consistent, and repeatable angled cuts. On one panel with the appearance side down, mark a line precisely where you want your final cut. Using a straightedge and a circular saw or jigsaw with a plywood-cutting blade, cut to within 1⁄8 " of the line on the waste side, as shown. Then reposition your straightedge, and use a router with a top-bearing straight bit to trim the panel to your marked line.
This piece now becomes the template for the remaining parts. Place this first piece atop other panels—again with the appearance side down—and mark lines about 1⁄8 " from the angled edge. Then rough-cut the panels to these lines. Instead of a straightedge, though, use the template piece atop the remaining pieces to guide your top-bearing straight bit and trim the rough edges to their final dimensions.
—Jeff Johnston, Rio Rancho, N.M.