I can stitch a 3/4'' circle with no trouble at all, without the groove nub, and cannot with it ,that thing just rips the leather all to H--l the 2 reversing stitches wont work because the nub is behind the stitch hole. All said i am new at this sewing thing ,but without the nub it works great !!! just MHO. now fahgetaboutit and grind that b---h off and have some fun with that cobra WOW What a machine ha.