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barbosa2007This is a fangirl/geek review about Kagi no Kakatta Heya, Ohno's latest drama. As Enomoto Kei is someone who is a crime prevention maniac, I thought I'd get slightly maniacal and write a bit about the scientific and crime prevention aspects that may not be fully elaborated in the drama.
Here's Kei in all his safe cracking glory, while Junko looks on with a bewildered expression.
I don't know about you, but my image of safe-cracking was something like this:
So why is Kei, the ultimate pro, not using a stethoscope or some other listening device to crack the safe? Before we can begin to understand safe cracking, we need to look at how a combination lock works.
How to open a combination lock will open if you know the combination:
This is what it looks like inside a typical lock feature of a safe:
Turning the combination dial (dark green) will allow you to turn the drive cam (white). The drive cam has a drive pin (white) attached to it. When the drive pin turns, it touches the wheel fly (yellow) on the 1st wheel . That in turn causes the 1st wheel (yellow) to turn.
The wheel fly on the 1st wheel then contacts the wheel fly on the 2nd wheel (purple) and causes the 2nd wheel to turn. The cycle goes on and on until the last wheel, depending on the number of wheels in the lock.
The security of the combination lock is increased by setting the combination dial to rotate in alternative directions, clockwise and anticlockwise. An animation showing how the wheels can be aligned can be seen HERE.
Once the wheels are aligned, as Kei says...
... the deadbolt, or fence, can slip into the space within the wheels, opening the lock.
So the best way to open a safe is to know the combination [series of numbers required to open the safe]. However, that is not possible in episode 1 as the branch chief was locked inside the safe with no way of getting to him.
So here is when dear Enomoto is required.
Lock Manipulation (Kei's expertise)
Lock manipulation can be summarized into 3 steps:
1. Determine the contact points
2. Discover the number of wheels
3. Graph your results
1. Determine the contact points
The drive cam has a notch. When the nose of the lever makes contact with this slope, there is a small click. By listening or feeling for the click, the locksmith can determine which numbers of the dial face correspond to the left and right side of that sloped notch.
The space between the first and second contact points is called the contact area and is the first step in discovering the combination.
2. Discover the number of wheels
After determining the contact area, the locksmith has to find out the number of wheels in the lock. The locksmith first turns the dial until it rests in a position opposite from the numbers of the contact area, like this:
Then the safecracker will slowly turn the dial clockwise. This causes the drive cam to begin spinning the wheels from that position. Each time the dial passes 60, the drive pin will click as a wheel is being picked up.
See how the drive cam (white) has picked up the 1st wheel (yellow) here as the drive cam turns clockwise? The yellow wheel will then pick up the purple wheel, which will then pick up the blue wheel. The locksmith will count each click, until there are no more.
There were 4 wheels in this episode, Kei will hear 4 clicks.
3. Graph your results
After the locksmith discovers the contact area and the number of wheels, he then resets the lock by turning it clockwise several times. He then sets the dial to zero.
Now, the locksmith will turn the dial slowly, anti-clockwise. He then listens for the tell-tale clicks that indicate the left and right contact point. He plots his result on a graph. He repeats this step, only this time, he sets the dial to 3 numbers to the left of zero, in this case, it's 97. And then he notes the clicks which indicate the first and second contact point. When he starts from 97, the contact area will vary slightly. The safe cracker repeats this process in intervals of three until all the positions on the dial have been graphed.
In the picture above, the three numbers inside the combination are 4, 37 and 61.
However, in episode 1, from Kei's laptop, let's assume that the 4 numbers (remember, the lock has 4 wheels) that hold the combination are 54, 77, 28 and 41.
Although the graph reveals where the wheels are in the proper position (as seen from the numbers), he doesn't know the order in which the wheels line up. Therefore, Kei must dial the numbers, in all possible combinations, until the safe opens. A four-number combination could have 24 possible variations. (You can try counting it yourself. I used a calculator. XD)
By trying all these variations, the safe will eventually open.
Enomoto, who manages to complete this task within 17 minutes, is a GENIUS.
source: How Stuff Works
Here's Kei in all his safe cracking glory, while Junko looks on with a bewildered expression.
I don't know about you, but my image of safe-cracking was something like this:
So why is Kei, the ultimate pro, not using a stethoscope or some other listening device to crack the safe? Before we can begin to understand safe cracking, we need to look at how a combination lock works.
How to open a combination lock will open if you know the combination:
This is what it looks like inside a typical lock feature of a safe:
Turning the combination dial (dark green) will allow you to turn the drive cam (white). The drive cam has a drive pin (white) attached to it. When the drive pin turns, it touches the wheel fly (yellow) on the 1st wheel . That in turn causes the 1st wheel (yellow) to turn.
The wheel fly on the 1st wheel then contacts the wheel fly on the 2nd wheel (purple) and causes the 2nd wheel to turn. The cycle goes on and on until the last wheel, depending on the number of wheels in the lock.
The security of the combination lock is increased by setting the combination dial to rotate in alternative directions, clockwise and anticlockwise. An animation showing how the wheels can be aligned can be seen HERE.
Once the wheels are aligned, as Kei says...
... the deadbolt, or fence, can slip into the space within the wheels, opening the lock.
So the best way to open a safe is to know the combination [series of numbers required to open the safe]. However, that is not possible in episode 1 as the branch chief was locked inside the safe with no way of getting to him.
So here is when dear Enomoto is required.
Lock Manipulation (Kei's expertise)
Lock manipulation can be summarized into 3 steps:
1. Determine the contact points
2. Discover the number of wheels
3. Graph your results
1. Determine the contact points
The drive cam has a notch. When the nose of the lever makes contact with this slope, there is a small click. By listening or feeling for the click, the locksmith can determine which numbers of the dial face correspond to the left and right side of that sloped notch.
The space between the first and second contact points is called the contact area and is the first step in discovering the combination.
2. Discover the number of wheels
After determining the contact area, the locksmith has to find out the number of wheels in the lock. The locksmith first turns the dial until it rests in a position opposite from the numbers of the contact area, like this:
Then the safecracker will slowly turn the dial clockwise. This causes the drive cam to begin spinning the wheels from that position. Each time the dial passes 60, the drive pin will click as a wheel is being picked up.
See how the drive cam (white) has picked up the 1st wheel (yellow) here as the drive cam turns clockwise? The yellow wheel will then pick up the purple wheel, which will then pick up the blue wheel. The locksmith will count each click, until there are no more.
There were 4 wheels in this episode, Kei will hear 4 clicks.
3. Graph your results
After the locksmith discovers the contact area and the number of wheels, he then resets the lock by turning it clockwise several times. He then sets the dial to zero.
Now, the locksmith will turn the dial slowly, anti-clockwise. He then listens for the tell-tale clicks that indicate the left and right contact point. He plots his result on a graph. He repeats this step, only this time, he sets the dial to 3 numbers to the left of zero, in this case, it's 97. And then he notes the clicks which indicate the first and second contact point. When he starts from 97, the contact area will vary slightly. The safe cracker repeats this process in intervals of three until all the positions on the dial have been graphed.
In the picture above, the three numbers inside the combination are 4, 37 and 61.
However, in episode 1, from Kei's laptop, let's assume that the 4 numbers (remember, the lock has 4 wheels) that hold the combination are 54, 77, 28 and 41.
Although the graph reveals where the wheels are in the proper position (as seen from the numbers), he doesn't know the order in which the wheels line up. Therefore, Kei must dial the numbers, in all possible combinations, until the safe opens. A four-number combination could have 24 possible variations. (You can try counting it yourself. I used a calculator. XD)
By trying all these variations, the safe will eventually open.
Enomoto, who manages to complete this task within 17 minutes, is a GENIUS.
source: How Stuff Works
