Public domain
Butte, Montana. Anaconda Copper Mining Company. First step in making bits for a pneumatic drilling machine is to heat a rod of the proper size; this rod is placed into machine which punches and forms the bit; this process is called drop forging. Bit plant of the Anaconda Copper Mining Company
From the collection of Library of Congress. Free to download, adapt and use — no permission needed.
Credit lineButte, Montana. Anaconda Copper Mining Company. First step in making bits for a pneumatic drilling machine is to heat a rod of the proper size; this rod is placed into machine which punches and forms . 1942-01-01. Lee, Russell. Farm Security Administration/Office of War Information Collection, Library of Congress. Public domain.