With respect to the above "answer", this tool has NO locking lever! It uses only a set screw to hold blades in place. It so happens that newer "star" mounting blades will fit into this tool easily, One must center the blade so the fingers of the star are outside of the raised circular surround of the hole. A washer (use a larger tapered one) and the set screw will then press the blade against the back surface of the bit holder. Tighten up this assembly, turn it on a cut away!