Abstract: A honing tool or mandrel mountable for rotation on a honing machine comprising an elongated substantially tubular member having inner and outer surfaces, the inner surface being conically tapered over substantially the length thereof, the outer surface including a portion having abrasive particles thereon, an elongated expander member positioned extending through the tubular member and having an outer surface tapered for making surface-to-surface contact with the tapered inner surface of the tubular member, the expander member being axially movable within the tubular member to change the diameter thereof uniformly along its length, the tubular member being attachable to a honing machine for rotation therewith adjacent one end portion thereof by a mounting structure which enables the tubular member to expand and contract thereat to increase or decrease the diameter thereof.