6 High Speed Steel Twist Drill Bits For Metalsmiths, Metal Working & Drilling. This is a new set of 6 high speed steel twist drill bits. Great for drilling ferrous metals, tough casting sand forgings, working hardened stainless steel and other hard steels and tough high tensile strength nonferrous metals like titanium. Includes on each of sizes: 55, 56, 59, 60, 64 and 67.