Abstract: Extrusion apparatus with means to effect movement of a die insert. The die insert has an upstream extension with two planes of movement. For each plane of movement, two thrust means are provided, one at each side of the insert for movement in one direction in the plane. Each thrust means acts at an angle to the required direction of movement of the insert, and produces thrust which is inclined to the direction of movement of the thrust means. In one arrangement, two arms move together, one at each side of the insert extension and place thrust upon the extension. In another arrangement there is cam operation controlled by operating rings surrounding the extension. For movement in each plane, the extension is held in that plane by stationary thrust means which, during movement, controls extension movement in the other plane.