A rotary knife fixture for cutting vegetable products such as raw potatoes into spiral shapes. The knife fixture includes a ring-shaped blade holder driven rotatably within a hydraulic product flow path. The blade holder includes at least one cutting blade, wherein the blade is twisted from a generally longitudinally aligned center axis outwardly in opposite circumferential directions with a sharpened leading edge set at a desired pitch angle. By controlling the pitch angle of the blade in relation to the blade rotational speed and velocity at which the potato travels along the hydraulic flow path, the resultant spiral cut shape is selected. By using multiple cutting blades at known axially spaced positions and selecting the angular position of each cutting blade in succession, the number of spiral shapes cut from each potato is selected. The blades can have a nontextured straight-cut edge, or a textured crinkle-cut edge, or a combination.

A rotary knife fixture configured for use in a water knife cutting system includes a ring, defining an internal aperture, and at least two spaced, angularly offset, parallel groups of parallel helically twisted cutting blades, extending across the aperture. The ring is configured to be placed in fluid communication with a hydraulic feed conduit of the water knife cutting system and for rotary motion about a rotational axis extending through the aperture. The groups of parallel blades are oriented generally perpendicular to the rotational axis. Each cutting blade has a sharpened cutting edge at one side thereof and is twisted generally about a center point thereof to define a pair of cutting edges oriented in opposite-facing circumferential directions. A vegetable product, fed through the aperture at a product speed, and with the rotary knife fixture rotating at a rotational speed, is substantially simultaneously cut into multiple helically twisted pieces.

A rotary knife fixture for cutting vegetable products into spiral shapes. The knife fixture includes a blade holder driven rotatably within a hydraulic product flow path. The blade holder includes at least one cutting blade, wherein the blade is twisted with a sharpened leading edge set at a desired pitch angle. By controlling the pitch angle of the blade in relation to the blade rotational speed and velocity at which the potato travels along the hydraulic flow path, the resultant spiral cut shape is selected. By using multiple cutting blades at known axially spaced positions and selecting the angular position of each cutting blade in succession, the number of spiral shapes cut from each potato is selected. The blades can have a nontextured straight-cut edge, or a textured crinkle-cut edge, or a combination.

A rotary cutter mechanism includes a rotary blade which is rotatably provided around a shaft center and which includes a first cutting edge portion, a counter blade which is provided to face a locus drawn by the first cutting edge portion of the rotating rotary blade and which includes a second cutting edge portion, and a protruding member which is provided on the edge portion of the rotary blade on the first direction side and which protrudes from the rotary blade toward a rotation direction side, the rotation direction side being a side on which the rotary blade faces the object to be cut in a case where the object to be cut is cut between the first cutting edge portion and the second cutting edge portion.