A method for forming at least one three-dimensional article through successive fusion of parts of a powder bed, comprising the steps of: providing at least one model of said three-dimensional article, moving a support structure in z-direction at a predetermined speed while rotating said support structure at a predetermined speed, directing a first and second energy beam causing said powder layer to fuse in first and second selected locations according to said model, wherein a first cover area of said first energy beam on said powder layer is arranged at a predetermined minimum distance and non-overlapping from a second cover area of said second energy beam on said powder layer, a trajectory of said first cover area and a trajectory of said second cover area are at least one of overlapping each other, abutting each other or separated to each other when said support structure is rotated a full lap.