the flanges 66 67 and knuckle 44 have horizontally aligned clearance holes for slidably receiving the mounting pin 48 a vertically threaded hole 68 is formed in the tip 42 of the arm 16 and the knuckle that intersects the mounting pin 48 a set screw 69 is threaded in the hole into engagement to axially fix the pin in the knuckle 44 and permit the shoes to rotate about the pin 48 as shown in fig6 through 9 the flanges on the center sections 60 terminate with a horizontal top wall 80 parallel to the bottom surface of the center section 60 the biasing spring 52 includes a center coiled section 72 and outwardly extending upper and lower arms 74 and 76 the upper arm 74 is retained between the outer wall of the arm 16 and the head of the fastener 52 the lower arm 76 is disposed in a transverse groove in the top wall 80 for normally maintaining the horizontal orientation of the shoes while yieldingly accommodating pivoting of the shoes during sewing operations the pressure shoes may be varied within the above criteria to handle differing materials and sewing constructions in order to handle welts a semicircular recess 82 may be formed on the inner wall of one of the shoes as shown in fig4 and 5 the width of the side flange 67 may be increased appropriately to handle the recess the surface.