Abstract: A core for winding metal sheet thereon to provide the sheet metal free of lap marks upon unwinding, the core having a generally cylindrical configuration and having an outside surface, said outside surface having a wedge-shaped notch formed generally transverse to winding direction of the core, the notch having a stepped end and a tapered end disposed opposite the stepped end, the stepped end extending from the surface to a bottom, the stepped end having a tapered end extending from the bottom of stepped end to the outside surface of said core to provide a transition zone.