Abstract: A concrete cutting saw and the process of using the concrete cutting saw for making a 45° chamfer cut at an edge of a 90° cut through a concrete wall. The process includes the steps of cutting a 90° cut through a concrete wall with a 90° saw mounted on a trolley riding along a track affixed to the concrete adjacent the cut. The 90° blade is lifted so that it is above the wall surface and a chamfer saw assembly is affixed to the frame. Next, the chamfer saw motor is started and the saw is lowered into a cutting position and the trolley is once again moved along the track, thereby forming a 45° chamfer along the edge of the cut. The apparatus utilizes a chamfer saw frame affixed to the trolley frame after the 90° saw blade has been lifted. The chamfer saw frame is mounted so that it is directly in the position which the 90° saw occupies when the 90° saw blade 16 is in a cutting position.