Cut dead-on angles with a portable circ saw
Sometimes you simply can't angle-cut the end of a board using a tablesaw or mitersaw because of the length of the workpiece or where you're working. For those times I use shop-made fixed-angle guides and a portable circular saw to get accurate, smooth, and controllable cuts.
Start with a piece of 1⁄4 " plywood or hardboard large enough to provide ample coverage across the width of your workpiece, with room to support your saw's shoe, and space for a handhold. Along one edge glue on a 1⁄2 ×1" stop fence. On the opposite face glue on a similar saw fence at exactly the angle you need relative to the stop fence (45° in the example shown). Mark the angle on the guide for future reference. Add a hole for hanging the guide.
Use your saw to cut the base's angled edge. Glue rubber or gasket material to the bottom of the guide to give it a cushioned grip. Now align the angled edge of the guide with your marked cutline, and saw with steady precision. If you need to slightly tweak the angle of the cut, simply place a thin shim or two between the stop fence and workpiece edge.
—Paul Fiebich, Derby, Kan.