Sharpening apparatus (2c) for sharpening a plurality of knives (2a) rotating on a chopping drum (2). The apparatus (2c) comprises a carriage (3) having a stone holder (14) for holding a sharpening stone (4). The carriage (3) is provided with adjustment means (11) for moving the stone holder (14) closer to the knives (2a) and holding means (9, 10) for holding a stone holder (14) in a fixed position. The apparatus further comprises a fixed track (5) which extends across the length of the drum along which the carriage (3) moves. The track (5) is not straight and a part of the track (5) activates the adjustment means (11) to move the stone holder (14) closer to the knives (2a) when the carriage (3) moves along part of the track (5).
