47 by means of a plurality of radially extending ribs 61 having parallel vertically extending sides 62 giving a transverse thickness that is relatively small compared to the vertical extent between the rib top edge 63 which slopes downward toward the upper surface of the outer bottom wall 47 and the radially extending rib undersurface or edge 64 which is spaced a predetermined distance above the lower edge of the conical portion inner edge 52 the space between the inner edge 52 and the hub vertical wall 56 defines an annular gap 66 which is thus covered only by the bridging of the radial ribs 61 and leaves sector shaped spaces therebetween a notch or recess 67 is formed on the lower inside corner of the edge 52 to receive the filter ring 71 which is also seated on the bottom edge 68 of vertical wall 56 and against the bottom edges 64 of the radial ribs 61 the filter ring 71 is formed as an annular sheet conforming to the bottom of the spin tub and has a circular outer edge 72 adapted to fit within the recess 67 so that the bottom surface 74 is smooth and substantially flush with the bottom surface of the outer bottom wall 47 this edge may be provided with several projecting tabs 73 which engage mating.