Portable Parabola Cutter Model SPC-1500 makes clean, circular cuttings in concrete and asphalt to maximum 15-cm. depth at speeds to 2,400 r.p.m. Spherical parabola blades one-step circular action eliminates the additional cross cuts of traditional linear blades. Diamond-segment blade edge reduces vibration and noise. Hardened tips inserted into peripheral slits protect blade against abrasion from accidental penetration into road foundation.