This tool at Smith’s Tavern is a corner/angle bit brace, made of cast iron with three wooden handholds. A corner brace was designed for drilling or driving screws in the corners of a work area, where the confined space would prevent the user from being able to make a full turn of the sweep handle on a standard brace. Corner braces have been superseded by corner power drills which can fit into tighter, smaller corners. As a result, there is not enough demand for corner braces, so they are no longer manufactured.
Unlike other braces that provide a direct drive from the user to the bit in the chuck, corner braces have two gears to redirect the turning motion of the sweep handle through a 45 degree angle to the chuck. They also have an additional part to their frame that forms a 90 degree angle that the sweep handle fits between. This additional part of the frame has a fixed corner side handle that is used to steady and apply pressure to the bit in the chuck.