Basic
Pic
king
&
The
Binding
Defect
The
atland
mo
del
highlights
the
basic
defect
that
enables
lo ck
pic
king
to
w
ork.
This
defect
makes
it
p ossible
to
op en
a
lo ck
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
sho
ws
ho
w
the
pins
of
a
lo ck
can
b e
set
one
at
a
time.
The
rst
step
of
the
pro cedure
is
to
apply
a
sheer
force
to
the
lo ck
b
y
pushing
on
the
b
ottom
plate.
This
force
causes
one
or
more
of
the
pins
to
b
e
scissored
b etw
een
the
top
and
b
ottom
plate.
The
most
common
defect
in
a
lo
c
k
is
that
only
one
pin
will
bind.
Figure
4.3a
sho
ws
the
left
pin
binding.
Even
though
a
pin
is
binding,
it
can
b e
pushed
up
with
a
pic
king
to ol,
see
Figure
4.3b.
When
the
top
of
the
k
ey
pin
reaches
the
sheer
line,
the
b ottom
plate
will
slide
slightly
.
If
the
pick
is
remov
ed,
the
driver
pin
will
b
e
held
up
by
the
o
v
erlapping
b ottom
plate,
and
the
k
ey
pin
will
drop
do
wn
to
its
initial
p osition,
see
Figure
4.3c.
The
slight
mo
v
emen
t
of
the
b
ottom
plate
causes
a
new
pin
to
bind.
The
same
pro cedure
can
b e
used
to
set
the
new
pin.
Thus,
the
pro cedure
for
one
pin
at
a
time
picking
a
lo
c
k
is
to
apply
a
sheer
force,
nd
the
pin
which
is
binding
the
most,
and
push
it
up.
When
the
top
of
the
k
ey
pin
reaches
the
sheer
line,
the
moving
p
ortion
of
the
lo ck
will
give
slightly
,
and
driv
er
pin
will
b
e
trapp ed
ab ov
e
the
sheer
line.
This
is
called
setting
a
pin.