The frame molding has a lovely shadow box effect. Splines are added for a decorative effect and to reinforce the joints.
Note: The angles of the setting mentioned can be determined from a chart.
Making the Miter Cuts
Set the table saw to cut at a 21 degree angle. Set the miter gauge at 49 degrees. Put the picture frame extension on the miter gauge. The frame extension sets the exact length of each piece and the scale shows the exact length of each picture frame part. Because the average frame is 11½" long, simply set the extension to 11½" and cut the two side pieces, then reset the gauge to the correct size for the top and bottom pieces.
Making Slots for the Splines
Make the spline slots by using a tenon master or make your own jig. Clamp the wood in tightly before making the spline cuts. Set the blade to cut the slot in the center of the stock. Clamp the stock so that the 45 degree angle is flat against the table.
Cutting the Splines
Using a band saw, cut blanks which are the desired thickness of the splines. (Splines can be difficult to cut on a table saw or with a jig saw.) Then cut the splines from the blanks.
Making Rabbet Cuts
A rabbet cut in the back of the frame is necessary to make the groove which will hold the glass and picture. A table saw with dado blades or a joiner can be used to make the rabbet cut. Set the saw or table at a 30 degree angle. Place the router flat on the stock with the bit away from the wood. Applying even pressure, make a rabbet cut on each piece of molding. Wear goggles, a mask and ear protection.
Insert all splines so that the grain on the spline goes from left to right, not up and down. Apply glue evenly to all joints. Clamp the frame together with frame clamps until the glue is completely dry and the joints are solid. Tap splines until they are even with the outer edge of the molding. The tails of the splines that protrude out can be cut with a utility knife and then sanded smooth.