Inside this long building, workers turned forged steel into finished parts and products through cutting processes including milling, drilling, turning, boring, and planing, shaping steel with great precision. Its size allowed machinists to manufacture massive parts. The company became famous for supplying guns, artillery, and equipment to the U.S. Army and Navy as well as to America's allies, and Bethlehem's machinists also made parts for the energy industry, including nuclear, oil, gas, and mining. In milling, a spinning cutter moved across the steel's surface and in all directions to shape a piece; in drilling, the cutter moved only up and down to remove material and make a hole; in turning, a piece of steel spun on a lathe while a cutter created cylindrical forms with specified profiles.