If you're not sure the factory edges on your plywood panels are straight and square, do some quick double-checks. Sight along the edge to see any curves or wobbles from the manufacturing process. This will also reveal dinged edges or delaminating areas that might not be visible straight-on. You can also use these photos to check for a straight edge (above left) and a square corner (below left).If you do find problems, your best straightener is your tablesaw. Cut your project pieces to 1⁄8" or more oversize with the factory edge against the tablesaw fence. Then cut them to final size with the newly ripped edge against the fence. Any irregularities in the factory edge of the plywood will be averaged out in the first cut, and then removed in the second.—Jonathan Walters, Bryantsville, Ky.