Originally published in 1975, the book "Techniques of Safe and Vault Manipulation," by Peter R. Senich and Howard Kyle, guides readers through the process of manipulating a combination lock. Lock manipulation is a process whereby a person is able to discover a safe's combination and open the lock using only the senses of touch and hearing.
Due to tolerances and variations in the manufacturing process, many safes produce a very small amount of physical resistance or discreet sounds when the combination wheel is dialed in a specific way. In lock manipulation, these sounds or changes in resistance are used to help determine the safe's combination. Although many professional safe crackers use a stethoscope or electronic listening device to help them hear these minute sounds, "Techniques of Safe and Vault Manipulation" teaches readers how to manipulate locks without the aid of any such devices.
Lock manipulation is usually a locksmith's preferred method for opening a lock where the combination has been lost, as it doesn't require any damage or repairs to the safe or lock. Lock manipulation is generally very time consuming, taking most professionals at least an hour or more, although there are some renowned safe crackers who can do it within minutes. While many types of combination locks can be easily manipulated by a trained professional, there are also many more sophisticated locks that feature a variety of anti-manipulation mechanisms.