Lapping I. The Carbide Methods of Holding and Proper Supnort In an effort to keep the cost of this ring down to a minimum, the first ... Since the carbide must be backed up and supported as rigidly as possible, much caution must be used in selecting the case material. ... in approximately .002aquot; on the l.D. By doing the shrinking before finishing the I.D., we save ourselves the operation of resizing the ring.