Abstract: The disclosure embraces a method of and apparatus or grinding machine particularly for grinding or sharpening the teeth of rotary cutters or cutting tools, the apparatus including a reciprocable ram mounting a rotatable grinding wheel, a vertically movable work or cutter supporting means and a work or cutter indexing means, the reciprocable ram, the feeding means for the grinding wheel, the movable cutter supporting means and the cutter indexing means each being driven or actuated by a hydraulically actuated rotary motor individual to each of these instrumentalities and controlled by means operable to effect automatically the grinding of all of the teeth of a cutter or cutting tool.