auto mechanic vs machinist

auto mechanic

noun
  • A person skilled in repairing and maintaining automobiles and other motor vehicles. 

machinist

noun
  • A person who operates machinery. 

  • A constructor of machines and engines; one versed in the principles of machines. 

  • One skilled in the use of machine tools for fashioning metal parts or tools out of metal. 

  • A person employed to shift scenery in a theater. 

How often have the words auto mechanic and machinist occurred in a corpus of books? (source: Google Ngram Viewer )