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Basic Scrubbing
At home you can take your time picking a lock, but in the
field,
speed is always
essential. This
chapter presents a
lock picking technique called
scrubbing that can quickly
open most locks.
The slow step in basic picking (
chapter 4) is locating the pin which is binding the most. The force diagram (
Figure 5.1) developed in
The Pin Column Modelchapter 5 suggests a fast way to select the
correct pin to
lift.
Assume that all the pins could be characterized by the same
force diagram. That is, assume that they all bind at once and that they all
encounter the same
friction. Now consider the
effect of running the
pick over all the pins with a
pressure that is great enough to
overcome the
spring and friction forces but not great enough to
overcome the
collision force of the key pin hitting the hull. Any
pressure that is above the flat portion of the force graph and below the top of the
peak will work. As the
pick passes over a
pin, the pin will
rise until it hits the
hull, but it will not enter the
hull. The collision
force at the
sheer line resists the
pressure of the
pick, so the pick rides over the pin without pressing it into the hull. If the proper
torque is being applied, the
plug will
rotate slightly. As the pick leaves the
pin, the
key pin will fall back to its initial position, but the
driver pin will catch on the edge of the plug and stay above the
sheer line. In theory one
stroke of the pick over the pins will cause the
lock to
open.
In practice,
at most one or two pins will
set during a
single stroke of the
pick, so several
strokes are necessary. Basically, you use the pick to
scrub back and forth over the pins while you adjust the amount of
torque on the plug. The exercises in
chapter 8 will teach you how to choose the correct
torque and
pressure.
You will find that the
pins of a
lock tend to set in a particular order. Many factors effect this order (see chapter 9), but the primary cause is a
misalignment between the
center axis of the
plug and the
axis on which the holes were drilled. If the axis of the
pin holes is skewed from the center line of the plug, then the pins will set from
back to
front if the
plug is turned one way, and from front to back if the plug is turned the other way. Many locks have this
defect.
Scrubbing is
fast because you don't need to pay attention to
individual pins. You only need to find the correct
torque and
pressure. Below, the steps of picking a lock by scrubbing are summarized. The
exercises will teach you how to
recognize when a pin is set and how to apply the correct
forces. If a lock doesn't open quickly, then it probably has one of the
characteristics described in chapter 9 and you will have to
concentrate on individual pins.
- Insert the pick and torque wrench. Without applying any torque pull the pic out to get a feel for the stiffness of the lock's springs.
- Apply a light torque. Insert the pick without touching the pins. As you pull the pick out, apply pressure to the pins. The pressure should be slightly larger than the minimum necessary to overcome the spring force.
- Gradually increase the torque with each stroke of the pick until pins begin to set.
- Keeping the torque fixed, scrub back and forth over the pins that have not set. If additional pins do not set, release the torque and start over with the torque found in the last step.
- Once the majority of the pins have been set, increase the torque and scrub the pins with a slightly larger pressure. This will set any pins which have set low due to beveled edges, etc.