a method of sequentially manufacturing a hollow knock pin avoids distortion due to the large forces of shearing . a rounded corner of a deep - drawn cup shape is supported closely both on the inside radius and on the outside radius by curved walls matched to the cup &# 39 ; s surface . the bottom of the cup is punched out close to the rounded corner . due to the close support , no distortion occurs during the shearing operation . the close support also permits the pin bore to be smoothed by plastic deformation of the metal , without elastic deformation of the lip adjacent to the rounded corner .