Abstract: The invention pertains to a self-cleaning high speed core boring tool for enlarging an existing deep hole. The elongated tool includes a shank held within a rotating tool holder, a central portion upon which cutting elements are mounted in diametrically located relationship, and the forward end of the tool comprises a cylindrical extension having a pair of spiral flutes defined therein each of which communicates with a cutting element for receiving chips. The flutes spiral in a direction opposite to the direction of tool rotation during boring whereby chips received within the flutes are displaced forwardly of the cutting elements to keep the cutting area free of chips.

Abstract: An electric circuit interrupter arranged to interrupt overload currents and having a pair of relatively movable normally closed disconnect contacts is associated with an electric circuit interrupter arranged to interrupt load currents and having a pair of relatively movable normally closed contacts forming a parallel circuit to the disconnect contacts only during opening of said disconnect contacts so as to prevent arcing at said disconnect contacts during opening thereof.