a gradual variation in its width similar to fig4 a b the ribs 514 and each step illustrated in fig5 a b may have a variety of geometric configurations including trapezoidal parabolic etc further while each of the u201c stepped u201d ribs is illustrated as having three incremental no limitation is intended on the scope of the present disclosure as shown in fig6 a rib 614 having two steps 614 a 614 b such that the width of rib 614 varies with along the height of the rib 614 is shown additionally any other number of steps e g greater than 3 may also be used in any of the variously embodiments disclosed herein additionally while each of the u201c stepped u201d or u201c graded u201d ribs discussed above is symmetrical with respect to a vertical centerline of the rib the present disclosure is not so limited for example as shown in fig7 a and 7b ribs 714 may be graded 715 or stepped with steps 714 a 714 b and 714 c on either the leading facing the direction in which the bit rotates or trailing not facing the direction in which the bit rotates edge of the rib 714 in a particular embodiment the trailing edge of the rib may be stepped or graded to allow for better cuttings removal in addition to possessing a varying width another aspect of the present.