Shop high performance Cobalt Drill Bit Sets built for stainless steel, hardened steel, cast iron, titanium, and other tough metals. Available in professional-grade M35 and M42 cobalt drill bit sets for fabrication, automotive, machining, and industrial drilling applications. Shop Drill Bit Warehouse for both M35 cobalt drill bits and M42 cobalt drill bits for drilling the metals that wear out standard HSS. M35 cobalt drill bits, with about 5% cobalt, are a solid all-around choice for stainless steel, cast iron and general maintenance work. M42 cobalt drill bits, with about 8% cobalt, run harder and hold their edge longer in hardened steel, titanium, Inconel and high-volume production drilling. If you often need cobalt drill bits for hardened steel, try out one of our drill bit sets. We can also produce custom sizes and sets necessary for your application. Give us a call at (800) 350-8665 for more information about our impressive selection.