Drill Hog USA 1/4″ to 1-3/8″ Cobalt M42 Step Drill Bit Set Spiral Flute. Drill Hog is proud to release the newest technology in step drill bits. These bits are made from Cobalt M42 steel which has a melting point of 2723 Fahrenheit! This new design features the exclusive spiral flute design. The spiral flutes allow the bit to cut 33% faster than standard step drills. These bits will drill through the toughest steel like truck frames, stainless steel, farm implements, spring steel, grade-8 bolts, and more!