A good cook changes his blade once a year — because he cuts. A mediocre cook changes his blade once a month — because he hacks. I've had this blade for nineteen years and cut up thousands of oxen, yet the blade is as sharp as if newly ground. There are spaces in the joints, and the blade has no thickness. Insert what has no thickness into spaces, and the blade moves freely with room to spare. That's why after nineteen years the blade is still like new.