Understanding Locks - The Basics

In order to understand how to pick a lock, we must first understand how a lock and it’s components work together. To get started. We will start with a basic 5 pin lock as a learning example. These are locks such as brinks and kwikset door knob locks that do not have a smart re-keying system. A lock of this type consists of a core, cylinder, a plug, , driver pins, key pins, and several springs. There are key terms that should be known in order to make the process more understandable.

The plug. The plug of a lock is the portion that turns when the key is inserted. The plug is held into the cylinder using a clip on the rear of the plug behind the core. The plug is part of a cylinder that contains the keyway, with tumbler chambers usually corresponding to those in the cylinder.

Core. Cores are one of a number of different pieces that make up a physical lock. The core is the circular cylinder that is inserted into the locking hardware. Inside the core are the driver pins that are lifted when a key is inserted, allowing the associated key to turn and open the lock while all other keys will. Each slot or chamber within a lock contains a spring, a driver pin, and a key pin. This combination is called a pin stack. The role of these components is to use spring pressure to push the driver pins into the plug and block its path from being able to rotate.

Cylinder. The entirety of these components when assembled together, make up the cylinder.

Key pin. These are small brass pins of varying sizes which correspond to the depth of cuts on a key.

Driver pin. Above each key pin is a corresponding set of driver pins, which are spring-loaded.

Pin stack. The pin stack is the combination of key pin and driver pin within a given chamber.

Shear line. The shear line is the line where the pins pass from the plug into the housing.

Whilst learning how to pick a lock, it is important to be able to identify which pin you are on. The pin closest to the opening of the key way is pin number one. Next is pin two, and so on. It is beneficial to fist feel for and locate each pin stack with your pick. Even slowly tracing over the key pin can be helpful while learning. Without applying tension, simply glide your pick slowly over each pin and learn their locations in order to aid in your ability to know where you are within the lock.

When picking a lock, the objective is to turn the plug. In order to rotate the plug, one must exploit built in tolerances within the lock, which allow for the plugs movement. This is achieved by applying a slight amount of tension to the plug to create a small amount of tension on the next binding pin. The amount of tension required is different for every lock. Start with a small amount and adjust as necessary. Where you want the tension is just where only one or two pin stacks are binding, yet still able to be manipulated without heavy force. The binding pin is the pin that shows the most resistance against movement. All other pin stacks should feel as though they move freely with only light spring pressure holding them in their resting position. If the pin stack moves freely, it is not the pin stack you want to target at this time. The binding pin stack is then coerced into place by lifting it so that the small gap between the driver pin and key pin align at the shear line. This is referred to as setting the pin and is often time accompanied by an audible “click”. Once this is completed, another pin stack will bind and becomes the next pin to set. This process is repeated for each pin stack the tension on the plug inhibits them from falling out of place, though it does not stop them from falling. It is possible for a pin stack to fall and need to be picked again. This can happen many times over the course of picking any lock. Once all pin stacks have been set at the shear line, the pin locations are identical to where they would be if the proper key was inserted. This then allows the plug to rotate, and opens the lock.