Figure 1. A pin tumbler lock what is billiards cylinder. Left: Cylinder face, the lock's "user interface." Note the keyway, which is cut into the plug, which in turn sits inside the shell. Observe that after you set the first pin, your three pin cylinder has one pin in each of three different states: set/not-binding, unset/not-binding, and unset/binding. In the locked state the plug is prevented from rotating by a set of movable pin stacks, typically under spring pressure, that protrude from holes in the top of the opening in the shell into corresponding holes drilled into the top of the plug. The basic skills of pin tumbler lock picking include selecting the proper tools, manipulating pins through the keyway, applying torque, and recognizing the state of each pin. Both the pick and the torque tool also amplify and transmit feedback about the state of the lock back to their user. Figure 2. Pin tumbler lock with a correct key inserted. Very "wavy" rake picks can simulate various key profiles, and can be surprisingly successful at opening poorly-made locks. The picks are available with blue plastic handles. Picks probe and lift the individual pin tumblers through the keyway, while torque tools control the degree and force of plug rotation.

If you tried to rotate the plug of such a lock without a key in the keyway, the top pin segment of each pin stack would block the plug at exactly the same number of degrees of rotation; each pin stack would contribute equally to preventing the plug from turning. Over the years, the locksmithing industry has settled on a number of "standard" pick designs. Note how the wards extend across the front of the pins; this is called a "paracentric" design in locksmithing parlance. Take note of the direction the keys turn on doors you use to help develop an inituition about which direction to apply torque. Note the border between the plug and shell, which forms the shear line, and the cuts in each pin stack resting within the plug. The plug/shell border is called the shear line. The plug can rotate freely only if the key lifts every pin stack's cut to align at the border between the plug and shell. Each pin stack is cut in one or more places perpendicular to its length.

When a key is inserted into the keyway slot at the front of the plug, the pin stacks are raised within the plug and shell. If this pin stack is slowly pushed up with torque applied to the plug, eventually its cut will reach the shear line and the plug will turn a bit more. The height (or cut depth) of a key under each pin stack position is called its bitting; the bitting of a key is the "secret" needed to open a lock. These imperfections are very small -- as little as .0001 inches in some cases -- but they are what allow us to manipulate ("pick") locks open without using the correct key. Repeat this exercise until you can reliably distinguish between a binding and a non-binding pin with very little lifting. Repeat until lock turns: - Locate the pin stack that's being pinched at the shear line (it resists slightly when pushed up) - Continue to push that pin stack up until its cut reaches the shear line and the plug turns slightly. Right: Side view, with part of the shell and plug cut away to expose the six pin stacks. Right: With all of the cuts at the shear line, the plug can rotate freely within the shell.

The top pin of the most misaligned pin stack becomes "pinched" at the shear line between the plug and the shell. The top pin of that pin stack will be trapped above the shear line, the bottom pin will fall freely, and now a new pin stack (the next most misaligned one) prevents further rotation. Some wafter lock cylinders (especially certain Chicago-brand locks) are double bitted, what is billiards with some wafers making contact with the key at the top of the keyway and others at the bottom. Picking tools are designed to perform one of two basic functions: manipulating pins and turning the plug. It involves two players or two teams, each aiming to pocket their designated balls (stripes or solids) and then sink the 8-ball to win. Two tools -- one for each function -- are used simultaneously when picking a lock. A few basic tools are sufficient to pick the majority of commonly used locks.