of the bit the surface 21 is the largest plane surface on the cutting head of the insert 17 the plane surface 21 contacts the wall of the hole and performs the gage cutting function since the surface 21 is relatively large compared to other surfaces on the insert 17 the lifetime of the insert 17 will be increased the insert 17 is formed by pressing granules of a wear resistant material such as tungsten carbide together with granules of a binder such as cobalt the wear resistant material granules and binder granules are pressed together with wax and formed in the desired insert shape the head of the insert may be formed in a die for example the head of the insert may be formed by a punch member which molds the end of the insert into the desired finished shape the inserts are de waxed in a furnace and sintered at a higher temperature in a furnace the insert is then press fit into the body of a cutter member with the asymmetric head oriented so that the extended plane surface of the insert is at gage very little if any gage grinding is required the foregoing should be contrasted with prior art inserts having symmetrical heads the prior art inserts are pressed into the cutter member and subsequently a gage surface is ground around the gage of a cutter producing ground flats on.