I moved into an apartment complex where the key is both unique to each apartment door, but every key can open the front door, how are both possible?
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Some keys/locks have TWO rows of teeth. In your example, every key is individual to its unit, but they are all master keyed to the front entry.
Every key has a few sections of the cut similar. The front door key core in the lock is only looking for those to line up.
My work has the opposite scenario. The core on each lock is stamped with a code, lets say C3AB. If you had a key stamped C3AB you can open it. But if you had a key stamped C3BB you could not. But lets step back a level, a key stamped C3A could open it, as well as a lock stamped with C3AA, C3A1, etc. It goes all the way back to our “Master Key” which is just labeled C. That key will open any door, padlock, etc that begins with a C.
That is the key I have. We actually use key cards for all the doors but some people have normal keys for emergency purposes. My position is responsible for the entire building (Data center) and if the key card server ever goes down, I am the guy who needs to be able to get in to fix it.
Every key has a few sections of the cut similar. The front door key core in the lock is only looking for those to line up.
My work has the opposite scenario. The core on each lock is stamped with a code, lets say C3AB. If you had a key stamped C3AB you can open it. But if you had a key stamped C3BB you could not. But lets step back a level, a key stamped C3A could open it, as well as a lock stamped with C3AA, C3A1, etc. It goes all the way back to our “Master Key” which is just labeled C. That key will open any door, padlock, etc that begins with a C.
That is the key I have. We actually use key cards for all the doors but some people have normal keys for emergency purposes. My position is responsible for the entire building (Data center) and if the key card server ever goes down, I am the guy who needs to be able to get in to fix it.
To expand on the answers already here, it’s likely some combination of master wafers and shared key cutting…
A common lock has a bunch of pins with springs, when these pins are pushed up in the wrong way they don’t let the lock turn, like that board game rush hour where you’ve got to clear a path for one object to move through.
A key is shaped so that it pushes all the pins correctly out of the way to let the lock spin, and also helps you spin the lock.
A master keyed system allows one lock to take multiple keys by having more than one cut in some of the pins. Normally, as the name suggests, you’d have a bunch of locks that have different keys but one special key that can open all of them… there’s technically not much stopping you from doing it the other way around, but it does make the front door lock much less secure.
To expand on the answers already here, it’s likely some combination of master wafers and shared key cutting…
A common lock has a bunch of pins with springs, when these pins are pushed up in the wrong way they don’t let the lock turn, like that board game rush hour where you’ve got to clear a path for one object to move through.
A key is shaped so that it pushes all the pins correctly out of the way to let the lock spin, and also helps you spin the lock.
A master keyed system allows one lock to take multiple keys by having more than one cut in some of the pins. Normally, as the name suggests, you’d have a bunch of locks that have different keys but one special key that can open all of them… there’s technically not much stopping you from doing it the other way around, but it does make the front door lock much less secure.
To expand on the answers already here, it’s likely some combination of master wafers and shared key cutting…
A common lock has a bunch of pins with springs, when these pins are pushed up in the wrong way they don’t let the lock turn, like that board game rush hour where you’ve got to clear a path for one object to move through.
A key is shaped so that it pushes all the pins correctly out of the way to let the lock spin, and also helps you spin the lock.
A master keyed system allows one lock to take multiple keys by having more than one cut in some of the pins. Normally, as the name suggests, you’d have a bunch of locks that have different keys but one special key that can open all of them… there’s technically not much stopping you from doing it the other way around, but it does make the front door lock much less secure.
I see a ton of answers here saying each door reads half the key. I could be ignorant here, but ive taken a lot of locks apart and I’ve never seen or heard of this kind of setup.
Making a single lock open to multiple keys is known as *cross-keying*. This is done using master pins/wafers/spacers
In a lock, there are key pins and driver pins. When you insert your key into the rotating part of the lock, called the *plug*, the key lifts the key pins to just the right height so that the boundary between the key pins and the driver pins on top of them all lines up at the top of the plug. With the pins out of position, the plug is prevented from rotating because it hits one or more pins. With them at this special height, the plug can rotate with the key pins inside the plug and the drivers outside.
Splitting either of these pins created a new height where everything lines up. This is done by using shorter pins and adding in a master pin (also called a master wafer, and similar names).
So in the simplest situation, your apartment key has exactly one key that opens it. Your front door has spacers in it so it also opens to that key as well. In order to keep down the number of spacers your front door needs, it’s common to have some shared heights between the keys that open individual apartments.
For example, your key might have the heights 12345 and your neighbor might have 15739. You both share the 1 so that the front door doesn’t need so many spacers that every key that fits in the lock also opens it.
It’s bad practice, but for a large enough building different apartments might share the same key. Or the front door might have one or two sets of pins taken out. If there’s no fifth pin, than any key that gets the other pins right will work, regardless of the fifth pin
I see a ton of answers here saying each door reads half the key. I could be ignorant here, but ive taken a lot of locks apart and I’ve never seen or heard of this kind of setup.
Making a single lock open to multiple keys is known as *cross-keying*. This is done using master pins/wafers/spacers
In a lock, there are key pins and driver pins. When you insert your key into the rotating part of the lock, called the *plug*, the key lifts the key pins to just the right height so that the boundary between the key pins and the driver pins on top of them all lines up at the top of the plug. With the pins out of position, the plug is prevented from rotating because it hits one or more pins. With them at this special height, the plug can rotate with the key pins inside the plug and the drivers outside.
Splitting either of these pins created a new height where everything lines up. This is done by using shorter pins and adding in a master pin (also called a master wafer, and similar names).
So in the simplest situation, your apartment key has exactly one key that opens it. Your front door has spacers in it so it also opens to that key as well. In order to keep down the number of spacers your front door needs, it’s common to have some shared heights between the keys that open individual apartments.
For example, your key might have the heights 12345 and your neighbor might have 15739. You both share the 1 so that the front door doesn’t need so many spacers that every key that fits in the lock also opens it.
It’s bad practice, but for a large enough building different apartments might share the same key. Or the front door might have one or two sets of pins taken out. If there’s no fifth pin, than any key that gets the other pins right will work, regardless of the fifth pin
I see a ton of answers here saying each door reads half the key. I could be ignorant here, but ive taken a lot of locks apart and I’ve never seen or heard of this kind of setup.
Making a single lock open to multiple keys is known as *cross-keying*. This is done using master pins/wafers/spacers
In a lock, there are key pins and driver pins. When you insert your key into the rotating part of the lock, called the *plug*, the key lifts the key pins to just the right height so that the boundary between the key pins and the driver pins on top of them all lines up at the top of the plug. With the pins out of position, the plug is prevented from rotating because it hits one or more pins. With them at this special height, the plug can rotate with the key pins inside the plug and the drivers outside.
Splitting either of these pins created a new height where everything lines up. This is done by using shorter pins and adding in a master pin (also called a master wafer, and similar names).
So in the simplest situation, your apartment key has exactly one key that opens it. Your front door has spacers in it so it also opens to that key as well. In order to keep down the number of spacers your front door needs, it’s common to have some shared heights between the keys that open individual apartments.
For example, your key might have the heights 12345 and your neighbor might have 15739. You both share the 1 so that the front door doesn’t need so many spacers that every key that fits in the lock also opens it.
It’s bad practice, but for a large enough building different apartments might share the same key. Or the front door might have one or two sets of pins taken out. If there’s no fifth pin, than any key that gets the other pins right will work, regardless of the fifth pin
Think of it like a 5 number combination lock. All the apartment keys can open combination 1-2-3–x-x. The front door only requires the first three digits. Your key could be 1-2-3-7-5. So every key starts with 123 allowing them to open the front door.
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