A method for sizing a section of a junction by orbital friction welding with an eccentric e, between a blade and a stub of a bladed disk for a turbomachine. The sized section has a rounded contour at one or two ends of said section along a chord of the blades, each corresponding to a leading edge or a trailing edge of said blades, said rounded contour(s) having over a sector of at least 120° an average radius of at least twice the eccentric e.