Cut a 90° Pocket Jig to Reach Angles Past Your Miter Saw's 45° Limit
Tape a straight board to the saw base and cut a 45° into each side of it, forming a 90° pocket. The saw cuts the jig itself, so at zero the blade bisects that pocket at exactly 45° — set a workpiece in it and the saw's own scale adds to that 45°.