A cutter bit adapted to be fixed onto a working surface of a rotating drum of a milling, planing, mining or reclaiming machine is provided. The body of the cutter bit is generally formed of a hardened steel, the cutting surface may be a diamond composition fixed in a step in the upper end of the cutter bit. The cutter bit includes a cutting surface, and the cutting surface may include non-parallel side edges and an upper cutting edge parallel to a lower edge. The lower edge may be any length sufficient to inhibit unintended angular displacement of the cutting surface during operation of the working surface. Alternatively or in addition, the cutting surface may be defined by three edges to allow the cutting surface to be removed and repositioned in at least a second orientation.