An apparatus for automatically sharpening microtome knives which repetitively strokes alternate sides of a microtome knife in a straight line motion against a planar non-stationary honing plate. The honing surface of the honing plate moves in a circular path within the principal plane of the plate. The honing surface of the honing plate is selectively positioned in a one of a plurality of parallel planes so that the knife edge is ground at a selected one of a corresponding plurality of angles. In a similar second mode of operation, a substantial pressure may be selectively applied to the knife against the honing plate to provide a high-speed sharpening operation. In a third mode of operation two worn honing plates are automatically resurfaced using a removable attachment to maintain a second honing plate in a stationary position supported by a moving abrasive-coated first honing plate. In this mode, the knife stroking means is stationary.