Patent ID: 6305885
Filing Date: 2001-10-23
Classification: B23B,Y10T

Abstract:
A hole enlargement apparatus used to increase the diameter of an existing hole in a workpiece for use in conjunction with a conventional large hole cutter of the type having a cylindrical cup having a toothed peripheral rim, a hub axially secured in a bottom portion of the cup, and a pilot bit axially and removably secured through the hub and cup, comprising:a guide member having a disc portion dimensioned to matingly fit within the existing hole, a rim portion connected to a rear portion of the disc portion adapted to seat on the workpiece around the hole to align and maintain the disc portion in the hole, and a disc center guide opening dimensioned to slidingly accept a shaft the diameter of the pilot bit;a drill bit replacement shaft having a hub end portion and an opposite disc end portion;disc retention means carried by the disc end portion of the drill bit replacement shaft to prevent the guide member from sliding off the disc end portion of the shaft; and,a disc bias means to bias and maintain the disc portion in the existing hole.