A new product from Rockler Woodworking and Hardware makes cutting perfect 45° miters a snap.
Called the 45 Degree Miter Sled, it utilizes the principle of complementary angles to assure that all corners are absolutely square. It eliminates the need to tweak your miter gauge to achieve a perfect fit when making frames. It produces joints with knife-edge accuracy.
A further innovation eliminates the need for auxiliary fences and stops by indexing off the saw fence. It works as follows:
The members of the frame are cut to their exact lengths, making sure the ends are square.
A member of the frame is clamped to the trailing edge of the Miter Sled, positioned so that the cut will be made leaving the length unchanged.
A relief block is attached to the saw fence by means of a clamp or with Rockler Sub Fence Clamp set to provide clearance for cutoffs, and brought into contact with the workpiece.
The first cut is made on all four pieces.
The workpiece is then put on the leading edge of the Miter Sled, butted against the clearance block, and the second cut is made.
All subsequent cuts are made in this manner.
It makes no difference that members of the frame may be of different lengths since they all index off the clearance block.
The mating angles are complementary (remember your high school geometry) and will form perfect right angles, resulting in a frame that closes properly and is square.