A tubular pin tumbler lock is a pin-tumbler lock with a round keyway. The keyway is a longitudinal slot in both the shaft and mating part. Woodruff cutters are used to cut the keyway for a woodruff key. A common type of internal broach is the "keyway" broach (C & D). Next, the broach is inserted and pushed through, cutting the keyway. The keyway in the hub has a taper that matches that of the tapered key. This keyway root crack has been previously theorized but not observed. However, it can produce the most accurate keyway out of all the processes. Keyway excavation on either side of the dam continued through 1964.