B67-606 IVORY NUT SCREW ARM PLOW PLANE. Auburn Tool Co. Solid boxwood, deeply oxidized but very clean with only a couple of tiny chips in the threads and around the tote end and a tight check in the toe. The ivory inner and outer nuts washers display numerous internal cracks not reaching the surface, and the four turned ivory knobs also have a few cracks, all lightly yellowed. Sandusky cutter. Ivory with this internal cracking should be relatively stable if maintained in an environment where variations in temperature, humidity and sunlight are minimal. Many collectors find this internal cracking visually enhances the appearance of older ivory. From the collection of Steve Dice. Good+ 500-1000