The primary purpose of hand files is to remove the rough edges from a piece of metal and to smoothen the surface. As they use high carbon steel, hand files are also generally tougher and durable than other types of files. On top of that, they also go through a heat treatment process that adds to their strength. To remove rough edges from metal using a hand file, you need to hold it in both hands. Then file the metal using only forward motion by only putting gentle pressure on the metal. After each forward motion, lift the file from the surface to avoid backstroke.