bitstock vs perforator

bitstock

noun
  • A hand tool consisting of a crank which holds a fitted rotating drill bit tip, designed to bore holes in rigid materials, by cutting a disc in a spiral fashion. 

perforator

noun
  • A tool or machine that makes holes, or perforates, materials such as paper and card. 

  • A perforating artery or vein 

  • A machine that can bore a tunnel underground 

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