A separator for centrifugally processing includes a rotatable drum having at least two drum parts, which can be rotated relative to one another at a screw thread. A drum tool is designed to open and close the drum by rotating the drum parts screwed together by the screw thread. The drum tool includes a retaining element attachable to the one drum part, a driver element attachable to the other, relatively rotatable drum part, and at least one rotation device for the relative rotation between the retaining element and the driver element together with the drum parts. The retaining and driver elements each having two or more points of engagement for the rotation device. The points of engagement are symmetrically arranged in such a way that forces produced by the rotation device produce a torque for the relative rotation of the drum parts, but no resulting force acting on the screwed drum parts on one side is produced.