This jig slides along the table saw fence and guides the wood as it is cut.
I flip the wood over and cut from each face of the board so the center slot is perfectly centered. I'll use a chisel to take care of that little bit of wood in the middle.
Although the table saw jig could be used to cut the tenon, I prefer to cut the tenon with the radial arm saw.
Note the use of the stop block to determine the length of the tenon.
The saw blade is actually moving during these pictures, but the camera has such a fast shutter speed that it looks like the blade is standing still.
The boards are a tad wider than they need to be, and I'll cut the frame to actual size after it's glued together.
