Watts Brothers Tool Works is a tool manufacturer located in Wilmerding, Pennsylvania. They are known for manufacturing drill bits that can drill square holes, including blind holes, which cannot be made with other methods such as broaching. The Harry Watts square drill bit is based on a Reuleaux triangle shape. It is used together with a guide and a particular chuck to make a square hole. Watts, Harry J.: "Drill or Boring Member", applied for November 1, 1916, granted September 25, 1917Scott Smith:"Drilling Square Holes", in The Mathematics Teacher, October 1993 (Volume 86 Number 7). Similarly, the company also manufactures drill bits for other angular holes such as pentagons and hexagons.
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