Mataya Laurance, Ewa; Shaw, Thomas C. (1999). The Complete Idiot's Guide to Pool & Billiards. Mizerak, Steve; Mataya Laurance, Ewa; Forsyth, Jerry (2003). Quick-Start Guide to Pocket Billiards. There is no reason to believe that the software used in electronc lock systems is any less subject to bugs, vulnerabilities and protocol failures than the typical (buggy) software used in other applications of similar complexity. Inexpensive and low-power embedded micro-controllers are increasingly serving as the foundation of modern security and access control systems. Mechanical combination locks are common on inexpensive padlocks, safe locks, and to control access to high security vaults. The training locks in the lab are a good start, but you will probably learn more quickly if you have access to your own personal practice locks as well. You will learn the basic fundamentals and much more on this website. The basic principles of operation are essentially the same as those of the standard pin tumbler lock, except that the tumblers are exposed at the front of the cylinder and a round ("tubular") key is used. Tubular locks suffer from the same manufacturing imperfections as other locks and so can be picked with essentially the same techniques.

In general, wafer lock picking employs the same techniques and tools as those used for pin tumbler locks. In a lock with six pin stacks with a uniform chance of a pin setting at either shear line, what is billiards the probability of a picked lock actually opening is only 1/64. Picking techniques for these locks involve the use of special torque tools designed to put torque on only one of the two concentric plugs. For example, Mul-T-Lock cylinders use special "telescoping" pins that contain two independently keyed tumblers. Each pins has a groove cut in its side at the position corresponding to its correct rotation. A correctly keyed wafer is flush with the plug on the top and the bottom and allows rotation. The sidebar must engage these grooves in order to retract and allow plug rotation. The disks are connected in sequence via interlocking cams such that one rotation of the dial engages the first disk, two rotations engage the second, and so on.

If the wafer is set too low by the key, it blocks rotation by extending out through the bottom of the plug, while if it is set too high, it extends out the top. While guncotton is dangerous to store, the hazards it presents can be minimized by storing it dampened with various liquids, such as alcohol. Guncotton manufacture ceased for over 15 years until a safer procedure could be developed. Safe and sustained production of guncotton began at the Waltham Abbey Royal Gunpowder Mills in the 1860s, and the material rapidly became the dominant explosive, becoming the standard for military warheads, although it remained too potent to be used as a propellant. Master ring cylinders (which are no longer in common commercial production but were once marketed by Corbin) use this mechanism to provide independently-keyed master keying. The design is based on the late 18th century British Bramah lock (still in production and use today). Many of these mechanisms involve the use of a "sidebar" that must retract before the plug can rotate. Tubular cylinders typically have four to eight pin tumblers arranged in a circular pattern around the circumference of the plug. Instead, they use flat "wafers," typically extending across the full height of the plug.

However, the design of the cylinder requires the use of special tools to manipulate the pins and apply torque. When you hold a cylinder in your hand you get different feedback from the pins than you do on a real door. India, they are commonly used for door locks and padlocks as well. It is always best to practice with your lock mounted to a door or wood platform, as they are here, or at least fixed in a vice. SFIC cylinders (such as those made by Best), used in large institutional lock systems, employ a similar mechanism to provide two kinds of keys: regular keys that operate the lock and control keys that unlock and remove the cylinder core itself. Some wafter lock cylinders (especially certain Chicago-brand locks) are double bitted, with some wafers making contact with the key at the top of the keyway and others at the bottom. These locks can be picked according to the same principles as used for ordinary pin tumbler locks, but, again, different tools are used to accommodate the different shape of the keyway.