Watts Brothers Tool Works is a tool manufacturer located in Wilmerding, Pennsylvania

Wilmerding, Pennsylvania

Wilmerding is a borough in Allegheny County, Pennsylvania, United States. The population was 2,190 at the 2010 census. It is located southeast of Pittsburgh. At the start of the twentieth century, it had extensive foundries and machine shops of the Westinghouse Air Brake Company. In 1900, the...

, USA. They are known for manufacturing drill bits which can drill

Drill

A drill or drill motor is a tool fitted with a cutting tool attachment or driving tool attachment, usually a drill bit or driver bit, used for drilling holes in various materials or fastening various materials together with the use of fasteners. The attachment is gripped by a chuck at one end of...

 square

Square (geometry)

In geometry, a square is a regular quadrilateral. This means that it has four equal sides and four equal angles...

 holes, including blind holes which cannot be made with other methods such as broaching

Broach (metalwork)

Broaching is a machining process that uses a toothed tool, called a broach, to remove material. There are two main types of broaching: linear and rotary. In linear broaching, which is the more common process, the broach is run linearly against a surface of the workpiece to effect the cut...

. The Harry Watt square drill bit is based on a Reuleaux triangle

Reuleaux triangle

A Reuleaux triangle is, apart from the trivial case of the circle, the simplest and best known Reuleaux polygon, a curve of constant width. The separation of two parallel lines tangent to the curve is independent of their orientation...

 shape, and is used together with a guide and a special chuck to make a square hole. Similarly, the company also manufactures drill bits for other angular holes such as pentagons and hexagons.