A file is a metalworking and woodworking tool used to cut fine
amounts of material from a workpiece. It most commonly refers to
the hand tool style, which takes the form of a hardened steel
bar with a series of sharp, parallel ridges, called teeth. Most
files have a narrow, pointed tang at one end to which a handle
can be fitted. Archaeologists have discovered rasps made from
bronze in Egypt, dating back to the years 1200 - 1000 B.C.,
Archaeologists have also discovered rasps made of iron used by
the Assyrians, dating back to the 7th Century B.C. Among the
drawings of Leonardo da Vinci is a sketch of a machine tool for
the cutting of files (the chisel would make one strike, swaging
a tooth, then automatically advance into position for the next
tooth, and strike again). Machining in the mid 19th century was
heavily dependent on filing, because milling practice was slowly
evolving out of its infancy. As late as the early 20th century,
manufacturing often involved filing parts to precise shape and
size. In today