rafter vs sprocket

rafter

noun
  • One of a series of sloped beams that extend from the ridge or hip to the downslope perimeter or eave, designed to support the roof deck and its associated loads. 

  • A raftsman. 

  • A flock of turkeys. 

verb
  • To furnish (a building) with rafters. 

  • To make (timber, etc.) into rafters. 

  • To plough so as to turn the grass side of each furrow upon an unploughed ridge; to ridge. 

sprocket

noun
  • A flared extension at the base of a sloped roof. 

  • A toothed wheel that enmeshes with a chain or other perforated band. 

  • The tooth of such a wheel. 

  • A placeholder name for an unnamed, unspecified, or hypothetical manufactured good or product. 

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