Abstract: A unitary lap blank has a front polishing portion and a rear disk portion contoured for coupling the disk to a chuck of the lathe and also to a chuck of the polishing machine. Preferably, the disk has a circular channel in its face opposed to its base and a pair of seats in the opposed face symmetrically diametrically aligned in a land defined by the channel. The channel is of diameter, width and depth and the seats are spaced for mating with complementary components on the lathe chuck. The disk also has a circular seat centered in the land and a pair of parallel side walls disposed along symmetrically opposed cords of the disk transverse to a line connecting the pair of seats, the side walls being spaced apart by a distance and the seat being of diameter and depth for mating with complementary components on the polishing machine chuck.