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The MIT lockpicking guide, complete with GIF diagr
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This is how the Guide looked to me (as best I can recreate it) when it was
given to me. You'll note the missing 'Legal Issues' section which whether
intentional or not, was not part of the guide as given to me. - Dave Ferret
{page 0}
MIT Guide to Lock Picking
Ted the Tool
February 14, 1992
{Page1}
Distribution
Copyright 1987, 1991 Theodore T. Tool. All right reserved.
Permission to reproduce this document on a non-profit basis
is granted provided that this copyright and distribution
notice is included in full. The information in this booklet is
provided for educational purposes only.
August 1991 revision.
Page2
Contents
1 It's Easy 4
2 How a Key Opens a Lock 5
3 The Flatland Model 7
4 Basic Picking & The Binding Defect 9
5 The Pin Column Model 11
6 Basic Scrubbing 17
7 Advanced Lock Picking 20
7.1 Mechanical Skills . . . . . . . . . . . . . . . . . . . 20
7.2 Zen and the Art of Lock Picking . . . . . . . . . . . . 20
7.3 Analytic Thinking . . . . . . . . . . . . . . . . . . . 21
8 Exercises 22
8.1 Exercise 1: Bouncing the pick . . . . . . . . . . . . . 22
8.2 Exercise 2: Picking Pressure . . . . . . . . . . . . . 23
8.3 Exercise 3: Picking Torque . . . . . . . . . . . . . . 23
8.4 Exercise 4: Identifying Set Pins. . . . . . . . . . . . 24
8.5 Exercise 5: Projections . . . . . . . . . . . . . . . . 24
9 Recognizing and Exploiting Personality Traits 25
9.1 Which Way To Turn . . . . . . . . . . . . . . . . . . . 25
9.2 How Far to Turn . . . . . . . . . . . . . . . . . . . . 27
9.3 Gravity . . . . . . . . . . . . . . . . . . . . . . . . 27
9.4 Pins Not Setting . . . . . . . . . . . . . . . . . . . 27
9.5 Elastic Deformation . . . . . . . . . . . . . . . . . . 27
9.6 Loose Plug . . . . . . . . . . . . . . . . . . . . . . 28
{page3}
9.7 Pin Diameter . . . . . . . . . . . . . . . . . . . . . 28
9.8 Beveled Holes and Rounded pins . . . . . . . . . . . . 30
9.9 Mushroom Driver Pins . . . . . . . . . . . . . . . . . 30
9.10Which Way To Turn . . . . . . . . . . . . . . . . . . . 34
9.11Which Way To Turn . . . . . . . . . . . . . . . . . . . 37
9.12Which Way To Turn . . . . . . . . . . . . . . . . . . . 37
9.13 Disk Tumblers . . . . . . . . . . . . . . . . . . . . . 38
10 Final Remarks 40
A Tools 41
A.1 Pick Shapes . . . . . . . . . . . . . . . . . . . . . . 41
A.2 Street cleaner bristles . . . . . . . . . . . . . . . . 42
A.3 Bicycle spokes . . . . . . . . . . . . . . . . . . . . 44
A.4 Brick Strap . . . . . . . . . . . . . . . . . . . . . . 45
B Legal Issues 46
{Page4}
Chapter 1
It's Easy
The big secret of lock picking is that it's easy. Anyone can
learn how to pikc locks.
The theory of lock picking is the theory of exploiting
mechanical defects. There are a few basic conept and
definitions but the bulk of the material consits of tricks for
opening locks with particular defects or characteristics. The
organization of this manual reflects this structure. The first
few chapters present the vocabulary and basic information
about locks and lock picking. There is no way to learn lock
picking without practicing, so one chapter presents a set of
carefully chosen excerses that will help yuou learn the skills
of lock picking. The document ends with a catalog of the
mechanical traits and defects found in locks and the
techniques used to recognize and exploit them. The first
appendix describes how to make lock picking tools. The other
appendix presents some of the legal issues of lock picking.
The exercises are important. The only way to learn how to
recignize and exploit the defects in a lock is to practice.
This means practicing many times on the saem lock as well as
practicing on many different locks. Anyone can learn how to
open desk and filing cabinet locks, but the ability to open
most locks in under thirty seconds is a skill that requires
practice.
Before gtting into the details of locks and picking, it is
worth pointing out that lock picking is just one way to bypass
a lock, though it does cause less damage than brute force
techniques. In fact, it may be easier to bypass the bolt
mechanism than to bypass the lock. It may also be easier to
bypass some other part of the door or even avoid the door
entirely. Remeber: There is always another way, usually a
better one.
{page5}
Chapter 2
How a Key Opens a Lock
This chapter presents the basuic workings of pin tumbler
locks, and the vocabulary used in the rest of this booket. The
terms used to describe locks and lock parts vary from
manufacture to manufacture and from city to city, so even if
you already understand the basic workings of locks, you should
look at figure 2.1 for the vocabulary.
Knowing how a lock works when it is opened by a key is only
part of what you need to know. You also need to know how a
lock responds to picking. Chapters 3 and 5 present models
which will help you understand a lock's response to picking.
Figure 2.1 introduces the vocabulary of real locks. The key
is inserted into the _keyway_ of the _plug_. The protrusions
on the side of the keyway are called _wards_. Wards restrict
the set of keys that can be inserted into the plug. The plug
is a cylinder which can rotate when the proper key is fully
inserted. The non-rotating part of the lock is called the
_hull_. The first pin touched by the key is called pin one.
The remaining pins are numbered increasingly toward the read
of the lock.
The proper key lifts each pin pair until the gap between
the _key pin_ and the _driver pin_ reaches the _sheer line_.
When all the pins are in this position, the plug can rotate
and the lock can be opened. An incorrect key will leave some
of the pins protruding between the hull and teh plug, and
these pins will prevent the plug from rotating.
{page6 - Diagram p6a, p6b, bottom label: Figure 2.1: Workings
of pin tumbler locks}
{page7}
Chapter 4
The Flatland Model
In order to become good at picking locks, you will need a
detailed understanding of how locks works and what happens as
it is picked. This document uses two models to help you
understand the behavior of locks. This chapter presents a
model that highlights interactions between pin positions.
Chapter 4 uses this model to explain how picking works.
Chapter 9 will use this model to explain complicated
mechanical defects.
The "flatland" model of a lock is shown in Figure 3.1 This
is not a cross section of a real lock. It is a cross secrtion
of a very simple kind of lock. The purpose of this lock is to
keep two plates of metal from sliding over each other unless
the proper key is present. The lock is constructed by playing
the two plates over each other and drilling holes which pass
through both plates. The figure shows a two hole lock. Two
pins are placed in each hole such that the hap between the
pins does not line up with the gap between the plates. The
bottom pin is called the _key pin_ because it touches the key.
The top pin is called the _driver pin_. Often the driver and
the key pins are just called the driver and the pin. A protrusion
on the underside of the bottom plate keeps the pins from
falling out, and a pring above the top plates pushed down on
the driver pin.
If the key is absent, the plates cannot slide over each other
because the driver pins pass through both plates. See Figure 3.3.
That is, the key lifts the key pin until its top reaches the lock's
sheer line. In this configuration the plates can slide past
each other.
Figure 3.3 also illustrates one of the important features
of real locks. There is always a sliding allowance. That is,
any parts which will slide past each other must be separated
by a gap. The gap between the top and bottom plates allows a
range of keys to open the lock. Notice that the right key pin
in Figure 3.3 is not raised as high as the left pin, yet the
lock will still open.
{page8 - diagrams p8a, p8b, p8c: labeled a] Figure 3.1:
Flatland model of a lock b] Figure 3.2: (a) Flatland key
raised pins c] Figure 3.3: (b) Proper key allows plates to
slide. }
{page9}
Chapter 4
Basic Picking & The Binding Defect
The flatland model highlights the basic defect that enables
lock picking to work. This defect makes it possible to open a
lock by lifting the pins one at a time, and thus you don't
need a key to lift all the pins at the same time. Figure 4.3
shows how the pins of a lock can be set one at a time. The
first step of the procedure is to apply a sheer force to the
lock by pushing on the bottom plate. This force casued one or
more the of pins to be scissored between the top and bottom
plate. The most common defect in a lock is that only one pin
will bind. Figure 4.3a shows the left pin binding. Even though
a pin is binding, it can be pushed up with a picking tool, see
Figure 4.3b. When the top of the key pin reaches the sheer
line, the bottom plate will slide slightly. If the pick is
removed the driver pin will be help up by the overlapping
bottom plate, and teh key pin will drop down to its initial
position, see Figure 4.3c. The slight movement of the bottom
plate causes a new pin to bind. The same procedure can be used
to set the new pin.
Thus, the procedure for _one pin at a time picking_ a lock
is to apply a sheer force, find the pin which is binging the
most and pish it up. When the top of the key pin reaches the
sheer line, the moving portion of the lock will give slgihtly,
and driver pin will be be trapped aboce the sheer line. This
is called _setting_ a pin.
Chapter 9 discusses the different defects that cause pins
to bind one at a time.
1. Apply a sheer force.
2. Find the pin that is binding the most.
3. Push that pin up until you feel it set at the sheer line.
4. Go to step 2.
Table 4.1: Figure 5: Picking a lock one pin at a time.
{page10 - diagrams p10a-c}
{page11}
Chapter 5
The Pin Column Model
The flatland model of locks can explain effects that involve
more than one pin, but a different model is needed to explain
the detailed behavior of a single pin. See Figure 5.1. The
pin-column model highlights teh relationship between the
torque applied and the amount of force needed t lift each pin.
IT is essential that you understand this relationship.
In order to understand the "feel" of lock picking you need
to know how the movement of a pin is effect by the torque
applied by your torque wrench (tensioner) and the pressure
applied by your pick. A good way to represent this
understanding is a graph that shows the minimum pressure
needed to move a pin as a function of how far the pin has been
displaced from its initial position. The remainder of this
chapter will derice that force graph from the pin-column modem.
Figure 5.2 shows a single pin position after torque has
been applied to the plug. The forces acting of the driver pin
are the friction from the sides, the spring contact force from
above, and the contact force from the key pin below. The
amount of pressure you apply to the pick determines the
contact force from below.
The spring force increases as the pins are pushed into the
hull, but the inscrease is slight, so we will assume that the
spring force is constant over the range of displacements we
are interested in. The pins will not move unless you apply
enough pressure to overcome the spring force. The binding
friction is proportional to how hard the driver pin is being
scissored between the plug and the hull, which in this case is
proportional to the torque. The more torque you apply to the
plug, the harder it will be to move the pins. To make a pin
move, you need to apply a pressure that is greater than the
sum of the spring and friction forces.
When the bottom of the driver pin reaches the sheer line,
the situation suddenly changes. See Figure 5.3. The friction
binding force drops to zero and the plug rotates slightly
(until some other pin binds). Now the only resistance to
motion is the spring force. After the top of the key pin
crosses the gap between the plug and the hull, a new contact
force arises from teh key pin striking the hull. This force
can be quite large, and it causes a peak in the amount of
pressure needed to move a pin.
If the pins are pushed further into the hull, they key pin
acquires a binding friction like the driver pin had in the
initial situation. See Figure 5.4. Thus, the amount of
pressure needed to move the pins before and after the sheer
line is about the same. Increasing the torque increases the
required pressure. At the sheer line, the pressure increases
dramatically due to the key pin hitting the hill. This
analysis is summarized graphically in figure 5.5.
{page12 - diagram, p12, Figure 5.1: The pin-column model}
{page13 - diagram, p13, Figure 5:2: Binding in the pin-column
model}
{page14 - diagram, p14, Figure 5.3: Pins at the sheer line}
{page15 - diagram, p15, Figure 5.4: Key pin enters hull}
{page16 - diagram, p16, Figure 5.5: Pressure required to move
pins}
{page17}
Chapter 6 {medium, bold}
Basic Scrubbing {large, bold}
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 5.5)
developed in chapter 5 suggests a fast way to select the
correct pin to lift. Assume that all the pins could be
characterized b 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
alll the pins witha 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 hill.
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, th epin will rise until it hits the hull, but it
will not enter the hull. See Figure 5.3. the cfollision force
at the sheer line resists the pressure of the pick, so the
pick rides over the pin without pressing it into the hill. 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. See figure
6.1. In theory one stroke of the pick over the pins will caue
the lock to open.
In practice, at most one or two pins will set during a
single stroke of the picj, so several strokes are necessary.
Basically, you use the picj to scrub back and forth over the
pins while you adjust the amount of torque on the plug. The
excercises 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 cetner
axis of the pug and the axis on which the holes were drilled.
See figure 6.2. 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 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. Figure 6.1 summarizes the steps of picking a
lock by scrubbing. 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.
{page18 - diagram 6.1 p18 6.1: Driver pin catches on plug}
{page 18 - continued:
1. Insert the pick and torque wrench. Without applying any
torque pull the pick out to get a feel for the stiffness of
the lock's springs.
2. 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.
3. Gradually increase the torque with each stroke of the pick
until pins begin to set.
4. Keeping the torque fixed, scrub back and fourth 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.
5. 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 not set low due to beveled
edges, etc.
Table 6.1: Figure 13 - Basic scrubbing
{page19 - diagram - p19a-c, bottom tag: Figure 6.2: Alignment
of plug holes}
{page20}
Chapter 7 { Medium, bold }
Advanced Lock Picking { Large, bold }
Simple lock picking is a trade that anyone can learn. However,
advanced lock picking is a craft that requires mechanical
sensitivity, physical dexterity, visual concentration and
analytic thinking. If you strive to excel at lock picking, you
will grow in many ways.
7.1 Mechanical Skills { medium bold }
Learning how to pull the pick over the pins is surprisingly
difficult. The problem is that the mechanical skills you
learned early in life involved maintaning a fixed position or
fixed path for your hands independant of the amount of force
required. IN lock picking, you must learn how to apply a fixed
force independant of the position of you hand. As you pull
the pick out of the lock you want to apply a fixed pressure on
the pins. The picks should bounce up and down in the keyway
according to the resistance offered by each pin.
To pick a lock you need feedback about the effects of your
manipulations. To get the feedback, you must train yourself to
be sensitve the sound and the feel of the pick passing over
the pins. This is a mechanical skill that can only be learned
with practice. The exercises will help you recognize the
important information coming from your fingers.
7.2 Zen and the Art of Lock Picking { medium bold }
In order to excel at lock picking, you must train yourself to
have a visually reconstructive imagination. The idea is to use
information from all your senses to build a picture of what is
happening inside the lock as you pick it. Basically, you want
to project your senses into the lock to receive a full picture
of how it is responding to your manipulations. Once you have
learned how to build this picture, it is easy to choose
manipulations that will open the lock.
All your senses provide information about the lock. Touch
and sound provide the most information, but the other senses
can reveal critical information. For example, your nose can
tell whether a lock has been lubricated recently. As a
beginner, you will need to use your eyes for hand-eye
coordination, but as you improve you will find it unnecessary
to look at the lock. In fact, it is better to ignore your eyes
to your sight to build an image of the lock based on the
information you receive from your fingers and ears.
The goal of this mental skill is to aquire a relaxed
concentration on the lock. Don't force the
{page 21}
concentration. Try to ignore the sensations and thoughts that
are not related to the lock. Don't try to focus on the lock.
7.3 Analytic Thinking { medium bold }
Each lock has it's own special characteristics which make
picking harder or easier. If you learn to recognize and
exploit the "personality traits" of locks, picking will go
much faster. Basically, you want to analyze the feedback you
get from the lock to diagnose it's personality traits and then
use your experience to decide on an approach to open a lock.
Chapter 9 discusses a large number of common traits and ways
to exploit or overcome them.
People underestimate the analytic involved in lock picking.
They think that the picking tool opens the lock. To them the
torque wrench is a passive tool that just puts the lock under
the desired stress. Let me propose another way to view the
situation. The pick is just running over the pins to get
information about the lock. Based on an analysis that
information the torque is adjusted to make the pins set at the
sheer line. It's the torque wrench that opens the lock.
Varying the torque as the picks moves in and out of the
keyway is a general trick that can be used to get around
several picking problems. For example, if the middle pins are
set, but the ends pins are not, you can increase the torque as
the pick moves over the middle pins. This will reduce the
chances of disturbing the correctly set pins. If some pin
doesn't seem to lift up far enough as the pick passes over it,
then try reduicing the torque on the next pass.
The skill of adjusting the torque while the pick is moving
requires careful coordination between your hands, but as you
become better at visualizing the process of picking the lock,
you will become better at this important skill.
{page22}
Chapter 8
Exercises
This chapter presents a series of exercises that will help you
learn the basic skill of lock picking. Some exercises teacha s
ignle skill, while others stress the coordination of skills.
When you do these exercises, focus on the skills, not on
opening the lock. If you focus on opening the lock, you will
get frustrated and your mind will stop learning. The goal of
each exercise is to learn something about the particular lock
you are holding and something about yourself. If a lock
happens to open, focus on the memory of what you were doing
and what you felt just before it opened.
These exercises should be practiced in short sessions.
After about thirty minutes you will find that your fingers
become sore and your mind looses its ability to achieve
relaxed oncentration.
8.1 Exercise 1: Bouncing the pick
This exercise helps you learn the skill of applying a fixed
pressure with the pick independent of how the pick moves upi
and down in the lock. Basically you waznt to learn how to let
the pick bounce up and down according to the resistance
offered by each pin.
How you hold the pick makes a different on how easy it is
to apply a fixed pressure. You want to hold it in such a way
that the pressure comes from your fingers or your wrist. Your
elbow and shoulder do not have the dexterity required to pick
locks. While you are scrubbing a lock notice which of your
joints are fixed, and which are allowed to move. The moving
joints are providing the pressure.
One way to hold a pick is to use two fingers to provide a
pivot point while anothing finger levelrs the pick to provide
the pressure. Which fingers you use is a matter of personal
choice. Another way to hold the pick is like holding a pencil.
With this method, your wrist provides the pressure. If your
wrist is providfing the pressure, your shoulder and elbow
should provide the force to move the pick in and out of the
lock. Do not use your wrist to both move the pick and apply
presure.
A good way to get used to the feel of the pick bouncing up
and down in the keyway is to try scrubbing over tyhe pins of
an open lock. The pins cannot be pushed down, so the pick must
adjust to the heights of the pins. Try to feel the pins rattle
as the pick moves over them. If you move the pick quickly, you
can hear the rattle. This same rattling feel will help you
recognize when a pin is set correctly. Ifg a pin appears to be
set but it doesn't rattle, then it is false set. False set
pins can be fixed by pushing them down farther, or by
releasing torque and letting them pop back to their
{page23}
initial position.
One last word of advice. Focus on the tip of the pick.
Don't think about how you are moving the handle; think about
how you are moving the tip of the pick.
8.2 Exercise 2: Picking pressure
This exercise will teach you the range of pressures you will
need to apply with a pick. When you are starting, just apply
pressure when you are drawing the pick out of the lock. Once
you have mastered that, try applying pressure when the pick is
moving inward.
With the flat side of your pick, push down on the first pin
of a lock. Don't apply any torque to the lock. The amount of
pressure you are applying should be just enough to overcome
the spring force. This force gives you an idea of the minimum
pressure you will apply with a pick.
The spring force increases as you push the pin down. See
if you can feel this increase.
Now see how it feels to push down the other pins as you
pull the pick out of the lock. Start out with both the pick
and torque wrench in the lock, but don't apply any torque. As
you draw the pick out of the lock, apply enough pressure to
push each pin all the way down.
The pins should spring back as teh pick goes past them.
Notice the sound that the pins make as they spring back.
Notice the popping feel as a pick goes past each pin. Notice
the springy feel as the pick pushes down on each new pin.
To help you focus on these sensations, try counting the
number of pins in the lock. Door locks, at MIT have seven
pins, padlocks usually have four.
To get an idea of the macdimum pressure, use the flat side
of your pick to push down all the pins in the lock. Sometimes
you will need to apply this much pressure to a single pin. If
you encounter a new kind of lock, perform this exercise to
determine the stiffness of its springs.
8.3 Exercise 3: Picking Torque
This exervise will teach you the range of torque you will need
to apply to a lock. It demonstrates the interaction between the
torque and pressure which was described in chapter 5.
The minimum torque you will use is just enough to overcome
the friction of rotating the plug in the hull. Use your torque
wrench to rotate the plug until it stops. Notice how much
torque is needed to move the plug before the pins bind. This
force can be quite high for locks that have been left out in
the rain. The minimum torque for padlocks includes the force
of a spring that is attached between the plug and the shackle
bolt.
To get a feel for the macimum value of torque, use the flat
side of the pick to push all the pins down, and try applying
enough torque to make the pins stay down after the pick is
removed. If your torque wrench has a twist in it, you may not
be able to hold down more than a few pins.
If you use too much torque and too much pressure you can
get into a situation like the one you just created. The key
pins are pushed too far into the hull and the torque is
sufficient to hold them there.
The range of picking torque can be found by gradually
increasing the torque while scrubbing the pins with the pick.
some of the pins will become harder to push down. Gradually
increase the torque until some of the pins set. These pins
will loose their springiness. Keeping the torque fixed,
{page 24}
use the pick to scrub the pins a few times to see if other
pins will set.
The most common mistakes of beginners is to use too much
torque. Use this excercise to find the minmum torque required
to pick the lock.
8.4 Exercise 4: Identifying Set Pins
While you are picking a lock, try to identify which pins are
set. You can tell a pin is set because it will have a slight
give. That is, the pin can be pushed down a short distance
with a light pressure, but it becomes hard to move after that
distance (see chapter 6 for an explanation). When you remove
the light pressure, the pin springs back up slightly. Set pins
also rattle if you flick them with the pick. Try listening for
that sound.
run the pick over the pins and try to decide whether the
set pins are in the front or back of the lock (or both). Try
identifying exactly which pins are set. Remember that pin one
is the frontmost pin (i.e., the pin that a key touches first).
The most important skill of lock picking is the ability to
recognize correctly set pins. This exercise will teach you
that skill.
Try repeating this exercise with the plug turning in the
other direction. If the front pins set when the plug is turned
one way, the back pins will set when the plug is turned the
other way. See Figure 6.2 for an explanation.
One way to verify how many pins are set is to release the
torque, and count the clicks as the pins snap back to their
initial position. Try this. Try to notice the difference in
sound between the snap of a single pin and the snap of two
pins at once. A pin that has been false set will also make a
snapping sound.
Try this exercise with different amounts of torque and
pressure. You should notice that a larger torque requires a
larger pressure to make pins set correctly. If the pressure is
too high, the pins will be jammed into the hull and stay there.
8.5 Exercise 5: Projection
As you are doing the exercises try building a pictuer in your
mind of what is going on. The picture does not have to be
visual, it could be a rough understanding of which pins are
set and how much resistance you are encountering from each
pin. One way to foster this picture building is to try to
remember your sensations and beliefs about a lock just before
it opened. When a lock opens, don't thing "that's over",
think "what happened".
This exercise requires a lock that you find easy to pick.
It will help you refine the visual skills you need to master
lock picking. Pick the lock, and try to remember how the
process felt. Rehearse in your mind how everything feels when
the lock is picked porperly. Basically, you want to create a
movie that records the process of picking the lock. Visualize
the motion of your muscles as they apply the correct pressure
and torque, and feel the resistance encountered by the pick.
Now pick the lock again trying to match your actions to the
movie.
By repeating this exercise, you are learning how to
formulate detailed commands for your muscles and how to
interpret feedback from your senses. The mental rehearsal
teches you how to build a visual understanding of the lock and
how to recognize the major steps of picking it.
{page 25}
Chapter 9
Recognizing and Exploiting
Personality Traits
Real locks have a wide range of mechanical features and
defects that help and hinder lock picking. If a lock doesn't
respond to scurbbing, then it probably has one of the traits
duscussed in this chapter. To open the lock, you must diagnose
the trait and apply the recommended technique. The exercises
will help you develop the mechanical sensitivity and dexterity
necessary to recognize and exploit the different traits.
9.1 Which Way To Turn
It can be very frustrating to spend a long time pickiong a
lock and then discover that you turned the plug the wrong way.
If you turn a plug the wrong way it will rotate freely until
it hits a stop, or until it rotates 180 degrees and the
drivers enter the keyway (see section 9.11). Sections 9.11
also explains how to turn the plug more than 180 degrees if
that is necessary to fully retract the bolt. When the plug is
turned in the correct direction, you should feel an extra
resistance when the plug cam engages the bolt spring.
The direction to turn the plug depends on the bolt
mechanism, not on the lock, but here are some general rules.
Cheap padlocks will open if the plug is turned in either
direction, so you can chose the direction which is best for
the torque wrench. WAll padlocks made by the Master company
can be opened in either direction. Padlocks made by Yale will
only open if the plug is turned clockwise. The double plug
Yale cylinder locks generally open by turning the bottom og
the keyway (i.e., the flat edge of the key) away from the
nearest doorframe. Single plug cylinder locks also follow this
rule. See Figure 9.1. Locks built into the doorknob usually
open clockwise. Desk and filing cabinet locks alsotend to open
clockwise.
When you encounter a new kind of lock mechanism, try
turning the plug in both directions. In the correct direction,
the plug will be stopped by the pins, so the stop will feel
mushy when you use heavy torque. In the wrong fdirection the
plug will be stopped by a metal tab, so the stop will feel
solid.
{page 26}
{diagrams for direction to turn p26a,b}
{page27}
9.2 How Far to Turn
The companion question to which way to turn a lock is how far
to turn it. Desk and filing cabinet locks generally open with
less than a quarter turn. Locks which are separate from the
doorknob tend to require a half turn to open. Deadbolt lock
mechanisms can requre almost a full turn to open.
Turning a lock more than 180 degrees is a difficult because
the drivers enter the bottom of the keyway. See section 9.11.
9.3 Gravity
Picking a lock that has the springs at the top is different
than picking one with the springs at the bottom. It should be
obvious how to tell the two apart. The nice feature of a lock
with the springs at the bottom is that gravity holds the key
pins down once they set. With the set pins out of the way, it
is easy to find and manipulate the remaining unset pins. It is
also straight forward to test for the slight give of a
correctly set pin. When the springs are on top, gravity will
pull the key pins down after the driver pin catches at the
sheer line. In this case, you can identify the set pins by
noticing that the key pin is easy to lift and that it does not
feel springy. Set pins also rattle as you draw the pick over
them because they are not being pushed down by the driver pin.
9.4 Pins Not Setting
If you sctub a lock and pins are not setting even when you
cary the torque, then some pin has a false set and it is
keeping the rest of the pins from setting. Consider a lock
whose pins preer to set from back to front. If the backmost
pin false sets high or low (see Figure 9.2), thgen the plug
cannot rotate enouggh to allow the other bins to bind. It is
hard to recognize that a pin has false set because the
springiness of the front pins makes it hard to sense the small
give of a correctly set back pin. The main symptom of this
situation is that the other pins will not set unless a very
large torque is applied.
When you encounter this situation, release the torque and
start over by concetrating on the back pins. Try a light
torque and moderate pressure, or heavy torque and heavy
pressure. Try to feel for the clikc that happens when a pin
reaches the sheer line and the plug rotates slightly. The
click will be easier to feel if you use a stiff torque wrench.
9.5 Elastic Deformation
The interesting events of lock picking happen over distances
measured in thousandths of an inch. Over such short
distances, metals behave like springs. Very little force is
necessary to deflect a piece metal over those distances, and
when the force is removed, the metal will spring back to its
original position.
Deformation can be used to your advantage if you want to
force several pins to bind at once. For example, picking a
lock with pins that prefer to be set from front to back is
slow because the pins set one at a time. This is particularly
true if you only apply pressure as the pick is drawn out of
{page28}
the lock. Each pass of the pick will only set the frontmost
pin that is binding. Numerous passes are requred to set all
the pins. IF the preference for setting is not very
strong(i.e. the axis of the plug holes is only slightly skewed
from the plug's center line), then you can cause additional
pins to bind by applying extra torque. Basically, the torque
puts a twist in the pug that causes the front of the plug to
be deflected further than the back of the plug. With light
torque, the back of the plug stays in its initial position,
but with medium to heavy torque, the front pin columns bend
enough to allow the back of the plug to rotate and thus cause
the back pins to bind. With the extra torque, a single stroke
of the pick can set several pins, and teh lock can be opened
quickly. Too much torque causes its own problems.
When the torque is large, the front pins and plug holes can
be deformed enough to prevent the pins from setting correctly.
In particular, the first pin tends to false set low. Figure
9.2 shows how excess torque can deform the bottom of the
driver pin and prevent the key pin from reaching the sheer
line. This situation can be recognized by the lack of give in
the first pin. Correctly set pins feel springy if they are
pressed down slightly. A falsely set pin lacks this
springiness. The solution is to press down hard on the first pin.
You may want to reduce the torque slightly, but if you reduce
torque too much then the other pins will unset as the first pin
is being depressed.
It is also possible to deform the top of the key pin. The
key pin is scissored between the plug and teh hull and stays
fixed. When this happens, the pin is said to be false set high.
9.6 Loose Plug
The plug is held into the hull by being wider at the front and
by having a cam on the back that is bigger than the hole
drilled into the hull. If the cam is not properly installed,
the plug can move in and out of the lock slightly On the
outward stroke of the pick, the plug will move forward, and in
and out of the lock slightly. On the outward stroke of the
pick, the plug will move forward, and if you apply pressure on
the inward stroke, the plug will be pushed back.
The problem with a loose plug is that the driver pins tend
to szet on the back of the plug holes rather than on the sides
of the holes. When you push the plug in, the drivers will
unset. You can use this defect to your afvantage by only
applying pressure on the outward or inward stroke of the pick.
Alternatively, you can use your finger or torque wrench to
prevent the plug from moving forward.
9.7 Pin Diameter
When the pair of pins in a particular column have different
diameters, that column will react strangely to the pressure of
the pick.
The top half of Figure 9.3 shows a pin column with a driver
pin that has a larger diameter than the key pin. As the pins
are lifted, the picking pressure is resisted by the binding
friction and the spring force. Once the driver clears the
sheer line, the plug rotates (until some other pin binds) and
the only resistance to motion is the spring force. If the key
pin is small enough and the plug did not rotate very far, the
key pin can enter the hull without colliding with the edge of
the hull. Some other pin is binding, so again the only
resistance to motion is the spring force. This relationship is
graphed in the bottom half of the Figure. Basically, the pins
feel normal at first, but then the lock clicks and the pin
becomes springy. The narrow key pin can be pushed all the way
into the hull without loosing its springiness, but when the
picking pressure is released, the key pin will fall back to
its initial position while the large driver catches on the
edge of the plug hole.
{page29 - Figure 9.2}
{page 30}
the problem with a large driver pin is that the key pin tends to get in the hull when
some other pin sets. Inmagine that a neighboring pin sets and the plug rotates enough to bind the
narrow key pin. If the pick was pressing down on the narrow key pin at the same time as it was
pressing down on the pin that set, then the narrow key pin will be in the hull and it will get stuckthere when the plug rotates.
The behavior of a large key pin is left as an exercise for the reader.
9.8 Beveled Holes and Rounded pins {Bold, Medium}
Some lock manufacturers (e.g., Yale) bevel the edges of the plug holes and/or round off the ends
of the key pins. This tends to reduce the wear on the lock and it can both help and hinder lock
picking. You can recognize a lock with these features by the large give in set pins. See figure 9.4.thgat is, the distance between the height at which the driver pin catches on the edge of the plug
hole and the height at which the driver pin catches on the edge of the plug
hole and the height at which the key pin hits the hull is larger (sometimes as large as a sixteenth
of an inch) when the plug holes are beveled or the pins are rounded. While the key pin is moving
between those two heights, the only resistance to motion will be the force of the spring. There
won't be any binding friction. This corresponds to the dip in the force graph shown in Figure 5.5
A Lock with beveled plug holes requires more scrubbing to open than a lock without beveled
holes because the driver pins set on the bevel instead of setting on the top of the plug. Thge plug
will not turn if one of the drivers is caught on a bevel. The key pin must be scrubbed again to
push the driver pin up and off the bevel. The left driver pin in Figure 9.6a is set. The driver is
resting on the bevel , and the bottom plate has moved enough to allow the right driver to bind.
Figure 9.6b shows what happens after the right driver pin sets. The bottom plate slides further to
the right and now the left driver pin is scissored between the bevel and the top plate. It is caughton the bevel. To open the lock, the left driver pin must be pushed up above the bevel. Once that
driver is free, the bottom plate can slide and the right driver may bind on its bevel.
If you encounter a lock with beveled plug holes, and all the pins appear to be set but the lock i
not opening, you should reduce torque and continue scrubbing over the pins. The reduced torque
will make it easier to push the drivers off the bevels. If pins unset when you reduce the torque, tr
increasing the torque and picking pressure. The problem with increasing the force is that you
may jam some key pins into the hull.
9.9 Mushroom Driver Pins {medium, Bold}
A general trick that lock makers use to make picking harder is to modift the shape of the driver pin
the most popular shapes are mushroom, spool and serrated, see Figure 9.7. The purpose of these
shapes is to cause the pins to false set low. These drivers stop a picking technique called vibratio
picking (see section 9.12), but they only slightly complicate scrubbing and one-pin-at-a-time pickin
(see chapter 4).
If you pick a lock and the plug stops turning after a few degrees and none of the pins can be
pushed up any further, then you known that the lock has modified drivers. Basically, the lip of the
driver has caught at the sheer line. See the bottom of Figure 9.7. Mushroom and spool drivers are
often found in Russwin locks, and locks that have several spacers for master keying.
You can identify the positions with the mushroom drivers by applying a light torque and pushing
{page 31 - Diagram 9.3 displacement of pin}
{page 32 - Figure 9.4 (top and bottom - 2 diags) }
{page 33 - Figure 9.5a, and 9.6b (a and b diagrams) }
{page 34}
up on each pin. The pins with mushroom drivers will exhibit a tendency to bring the plug back to
the fully locked position. By pushing the key pin up you are pushing the flat top fo the key pin
against the tilted bottom of the mushroom driver. this causes the drive rto straighten up which
in turn causes the plug to unrotate. You can use this motion to identify the columns that have
mushroom drivers. Push those pins up to sheer line; even if you lose some of the other pins in the
process they will be easier to re-pick than the pins with mushroom drivers. Eventually all the pins
will be correctly set at the sheer line.
One way to identify all the positions with mushroom dirvers is to use the flat of your pick to
push all the pins up about halfway. This should put most of the drivers in their cockable position
and you can feel for them.
to pick a lock with modified drivers, use a lighter torque and heaveier pressure. you want to
error on the side of pushing the key pins too far into the hull. In fact, another way to pick these
locks is to use the flat side of your pick to push the pins up all the way, and apply very heavy
torque to hold them there. Use a scrubbing action to vibrate the key pins while you slowly reduce
the torque. Reducing the torqyue reduces the binding friction on the pins. The vibration and spinrg
force cause the key pins to slide down to the sheer line.
the key to picking locks with modified drivers is rocognizing incorrectly set pins. A mushroom
driver set on its lip will not have the springy give of a correctly set driver. practice recognizingthe
difference.
9.10 Master Keys {you guessed it, Medium BOld!}
Many applications require keys that oopen only a single lock and keys that opena group of locks.
the keys that open a single lock are called _change keys_ and the keys that open multiple locks are
called _master keys_. To allow both the change key and the master key to open the same lock, a
locksmith adds an extra pin called a _spacer_ to some of the pin columns. See Figure 9.8. The effectof the spacer is to create two gaps in the pin column that could be lined up with the sheer line.
Usually the change key aligns the top of the spacer with the sheer line, and the master key aligns
the bottom of the spacer with the sheer line (the idea is to prevent people from filing down a chang
key to get a master key.) In either case the plug is free to rotate.
In general, spacers make a lock easier to pick. They increase the number of opportunities to se
each pin, and they make it more likely that the lock can by opened by setting all the pins at about
the same height. In most cases only two or three positions will have spacers. You can recognize a
position with a spacer by the two clicks you feel when the pin is pushed down. If the spacer has
a smaller diameter than the driver and key pins, then you will feel a wise springy region because
the spacer will not bind as it passes through the sheer line. It is more common for the spacer to belarger than the driver pin. You can recognize this by an increase in friction when the spacer passesthrough the sheer line. Since the spacer is larger than the driver pin, it will also catch better onthe plug. If you push the spacer further into the hull, you will feel a strong click when the bottomof the spacer clears the sheer line.
Thin spacers can cause serious problems. If you apply heavy torque and the plug has beveled
holes, the spacer can twist and jam at tyhe sheer line. It is also possible for the spacer to fall ito
the keyway if the plug is rotated 180 degrees. See section 9.11 for the solution to this problem.
{Page 35 - Diagrams, Mushroom driver, spool, serrated, then large plug example}
{Page 36 - Figure 9.8: Spacer pins for master keying}
{page 37 - Figure 9.9: Spacer or driver can enter keyway}
{page 37 - continues with text}
9.11 Driver or Spacer Enters Keyway
Figure 9.9 shows how a spacer or driver pin can enter the keyway when the plug is rotated 180
degrees. You can prevent this by placing the flat side of your pick in the bottom of the keyway
BEFORE you turn the plug too far. If a spacer or driver does enter the keyway and prevent you from
turning the plug, use the flat side of your pick to push the spacer back into the hull. You may needto use the toruqe wrench to relieve any sheer force that is binding the spacer or driver. If that
doesn't work try raking over the drivers with the pointed side of your pick. If a spacer falls into
the keyway completely, the only option is to remove it. A hook shaped piece of spring steel works
well for this, though a bent paperclip will work just as well unless the spacer becomes wedged.
9.12 Vibration Picking {medium Bold - Probably around 20 point, other type ~10}
Vibration picking works by creating a large gap between the key and driver pins. The underlying
principle is familar to anyone who has played pool. When the queue ball strikes another ball
{page 38}
squarely, the queue ball stops and the other ball heads off with the same speed and direction as
the queue ball. Now imagine a device that kicsk the tips of all the key pins. The key pins would
transfer their momentum to the driver pins which would fly up into the hull. If you are applying a
light torque when this happens, the plug will rotate when all the drivers are above the sheer line.
9.13 Disk Tumblers
the inexpensive locks found on desks use metal disks instead of pins. Figure 9.10 shows the
basic workings of these locks. the disks have the same outline but differ in the placement of the
rectangular cut.
these locks are aesy to pick with the right tools. Because the disks are placed close together
a half-round pick works better than a half-diamond pick (see Figure A.1}. you may also need a
torque wrench with a narrower head. Use moderate to heavy torque.
{page 39 - Figure 9.10 Workings of a disk tumbler lock, 3 pictures}
{page 40}
Chapter 10
Final Remarks
Lock picking is a craft, not a science. This document prsents the knowledge and skills that are
essential to lock picking, but more importantly it provides you with models and excercises that willhelp you study locks on your own. To excel at lock picking, you must practice and develop a style
which fits you personally. Rember that the best technique is the one that works best for you.
{Page 41}
Appendix A
Tools
This appendix describes the design and construction of lock picking tools.
A.1 Pick Shapes
Picks copme in several shapes and sizes. Figure A.1 shows the most common shapes. The handle
and tang of a pick are the same for all picks. The handle must be comfortable and the tang must
be thin enough to avoid bumping pins unnecessarily. If the tang is too thing, then it will act like
a spring and you will loose the feel of the tip interacting with the pins. The shape of the tip
determines how easily the pick passes over the pins and what kind of feedback you get from each pin.
The design of a tip is a compromise between the ease of insertion, ease of withdrawal and feel f
the interaction. The half diamond tip with shallow angles is easy to insert and remove, so you can
apply pressure when the pick is moving in either direction. It can quickly pick a lock that has litte
variation in the lengths of the key pins. If the lock requires a key that has a deep cut between
two shallow cuts, the pick may not be able to push the middle pin down far enough. The half
diamond pick with steep angles could deal with such a lock, and in general steep angles give you
better feedback about the pins. Unfortunately, the steep angles make it harder to move the pick
in the lock. A tip that has a shallow front angle and a steep back angle works well for Yale locks.
The half round tip works well in a disk tumbler lock. See section 9.13. The full diamond and
full round tips are useful for locks that have pins at the top and bottom of the keyway.
The rake tip is designed for picking pins one by one. It can also be used to rake over the pins
but the pressure can only be applied as the pick is withdrawn. The rake tip allows you to carefully
feel each pin and apply varying amounts of pressure. Some rake tips are flat or dented on the top
to make it easier to align the pick on the pin. The primary benefit of picking pins one at a time
is that you avoice scratching the pins. Scrubbing scratches the tips of the pins and the keyway, andit spreads metal dust throughout the lock. If you want to avoid leaving traces, you must avoid
scrubbing.
The snake tip can be used for scrubbing or picking. when scurbbing, the multiple bumps
generate more action than a regular pick. The snake tip is particularly good at opening five pin
household locks. When a snake tip is used for picking, it can set tow or three pins at once. Basicaly,
the snake pick acts like a segment of a key which can be adjusted by lifting and lowering the tip, b
tilting it back and forth, and by using either the top or bottom of the tip. You should use moderate
{page 42}
to heavy torque with a snake pick to allow several pins to bind at the same time. This style of
picking is faster than using a rake and it leaves as little evidence.
A.2 Street Cleaner Bristles
The spring steel bristles used on stret cleaners make excellent tools for lock picking. The bristleshave the right thickness and width, and they are easy to grind into the desired shape. The resultingtools are springy and strong. Section A.3 describes how to make tools that are less springy.
The first step in making tools is to sand off any rust on the bristles. Course grit sand paper
works fine as does stel wool cleaning pad (not copper wool). If the edges or tip of the bristle are
worn down, use a file to make them square.
A torque wrench has a head and a handle as shown in figure A.2. the head is usuaully 1/2 to
3/4 if an inch long and the handle varies from 2 to 4 inches long. The head and the handle are
separated by a bend that is about 80 degrees. The head must be long enough to reach over any
protrusions (such as a grip-proof collar) and firmly engage the plug. A long handle alows delicate
control over torque, but if it is too long, it will bump against the doorframe. The handle, head
and bend angle can be made quite small if you want to make tools that are easy to conceal (e.g.,
in a pen, flashlight or belt buckle). Some torque wrenches have a 90 degree twist in the handle.
The twist makes it easy to control the torque by controlling how far the handle has been deflected
from its rest position. The handle acts as a spring which sets the torque. The disadvantage of this
method of setting the torque is that you get less feedback about the rotation of the plug. To pick
difficult locks you will need to learn how to apply a steady torque via a stiff handled torque wrenc.
the width of the head of a torque wrench determines how well it will fit the keyway. Locks
with narrow keyways (e.g. desk locks) need torque wrenches with narrow heads. Before bending
the bristle, file the head to the desired width. A general purpose wrench can be made by narrowing
the tip (about 1/4 inch) of the head. The tip fits small keyways while the rest of the head is wide
enough to grab a normal keyway.
The hard part of making a torque wrench is bending the bristle withouth cracking it. To make
the 90 degree handle twist, clamp the head of the bristle (about one inch) in a cise and use pliers
to grasp the bristle about 3/8 of an inch above its vise. You can use another pair of pliers insteadof a vise. Apply a45 degre twist. Try to keep the axis of the twist lined up with the axis of the
bristle. Now move the pliers back another 3/8 inch and apply the remaning 45 degrees. You will
need to twist the bristle more than 90 degrees in order to set a permanent 90 degree twist.
To make the 80 degre head bend, lift the bristle out of the vise by about 1/4 inch (so 3/4 inchis still in the vise). Place the shank of a screw driver against the bristle and bend the spring stel
around it about 90 degrees. This should set a permanent 80 degre bend in the metal. Try to keep
the axis of the bend perpendicular to the handle. The screwdirver shank ensures that the radius of
curvature will not be too small. Any rounded object will work (e.g. drill bit, needle nose plies, ora pen cap). If you have trouble with this method, try grasping the bristle with two pliers separatedby about 1/2 inch and bend. This method produces a gentle curve that won't break the bristle.
A grinding wheel will greatly speed the job of making a pick. It takes a bit of practice to lear
how to make smooth cuts with a grinding wheel, but it takes less time to practice and make two or
three picks than it does to hand file a single pick. The first step is to cut the front angle of thepick. Use the front of the wheel to do this. Hold the bristle at 45 degrees to the wheel and move
the bristle side to side as you grind away the metal. Grind slowly to avoid overheating the metal,
{page 43 - Figure A.1: Selection of pick shapes -- Top Generic, then one of each}
{page 44 - Figure A.2: Torque Wrenches (2 side by side - upright}
{page 44 - cont..}
which makes it brittle. If the metal changes color (to dark blue), you have overheated it, and you
should grind away the colored portion. Next, cut the back angle of the tip using the corner of the
wheel. Usually one corner is sharper than the other, and you should use that one. Hold the pick
at the desired angle and slowly push it into the corner of the wheel. The side of the stone should
cut the back angle. Be sure that the tip of the pick is supported. If the grinding wheel stage is
not close enough to the wheel to support the tip, use needle nose pliers to hold the tip. The cut
should pass through about 2/3 of the width of the bristle. If the tip came out well, continue.
Otherwise break it off and try again. You can break the bristle by clamping it into a vice and
bending it sharply.
The corner of the wheel is also used to grind the tang of the pick. Put a scratch mark to indicte
how far back the tang should go. The tang should be long enough to allow the tip to pass over
the back pin of a seven pin lock. Cut the tang by making several smooth passes over the corner.
Each pass starts at the tip and moves to the scratch mark. Try to remove less than a 1/16th of
an inch of metal with each pass. I use two fingers to hold the bristle on the stage at the proper
angle while my other hand pushed the handle of the pick to move the tang along the corner. Use
whatever technique works best for you.
Use a hand file to finish the pick. It should feel smooth if you run a finger nail over it. Anyroughness will add noise to the feedback you want to get from the lock.
the outer sheath of phone cable can be used as a handle for the pick. Remove three or four of
the wires from a length of cable and push it over the pick. If the sheath won't stay in place, you
can put some epoxy on the handle before pushing the sheath over it.
A.3 Bicycle Spokes
An alternative to making tools out of street cleaner bristles is to make them out of nail and bcyle
spokes. These materials are easily accessable and when they are heat treated, they will be stronger
than tools made from the bristles.
A strong torque wrench can be constructed from an 8-penny nail (about .1 inch diameter). First
heat up the point with a propane torch until it glows red, slowly remove it from the flame, and let
it air cool; this softens it. The burned of a gas stove can be used instead of a torch. Grind it dow
{page 45}
into the shape of a skinny screwdriver blade and bend it to about 80 degrees. The bend should be
less than a right angle because some lock faces are recessed behind a plate. (called an escutcheon)
and you want the head of the wrench to be able to reach about half an inch into the plug. Temper
(harden) the torque wrench by heating to bright orange and dunking it into ice water. You will
wind up with a virtually indestructible bent screwdriver that will last for years under brutal use.
Bicycle spokes make excellent picks. Bend one to the shape you want and file the side of the
business end flat such that it's strong in the vertical and flexy in the horizontal direction. Try aright-angle hunk about an inch long for a handle. For smaller picks, which you need for those reallytiny keyways, find any large-diameter spring and unbend it. If your careful you don't have to
play any metallurgical games.
A.4 Brick Strap
For perfectly serviceable key blanks that you can't otherwise find at the store, use the metal strapthey wrap around bricks for shipping. It's wonderfully handy stuff for just about anything you
want to manufacture. To get around side wards in the keyway, you can bend the strap lengthwise
by clamping it in a vice and tapping on the protruding part to bend the piece to the required angle.
Brick strap is very hard. It can ruin a grinding wheel or key cutting machine. A hand file is
the recommended tool for milling brick strap.
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