Almost everybody uses a lock and key at least once a day. Whether it’s leaving your house, starting your car, or unlocking your bike, locks and keys serve an important function in the fabric of our lives. But have you ever stopped to wonder, “How do locks work?” You put a key inside and turn it, but what goes on inside the lock is a mystery. 

The pin-and-tumbler locks, also known as deadbolts, that we use today have been around since the 1800s. Even today, they’re a fascinating bit of engineering. But a little research, they are easy to understand. 

Read on if you want to find out how a lock works!

Why Would I Want to Know How a Lock Works?

You may be thinking to yourself, “But I’m an upstanding, law-abiding citizen! Why would an honest do-gooder like me ever need to know how a lock works?” You would be surprised!

There are plenty of practical reasons why some technical knowledge could come in handy. The most obvious one, of course, is being able to pick your own lock! If you have ever lost your keys while running errands, you know how annoying (and expensive) it is to get locked out. 

It’s much easier and more efficient to get the lock open yourself! With some knowledge of simple tools, you can open many locks all by yourself.

Being able to pick locks also allows you to test the security of your home. Once you realize how easy it is to undo the common deadbolt, you are sure to invest in a more secure device. And once you have a lock you, a seasoned lock picker, can’t open, then you can rest assured that the average burglar won’t be able to either. 

And, at the end of the day, lock picking is a fun hobby in and of itself. You’ll feel just like Sherlock Holmes, building your collection of locks and testing your speed and accuracy! 

The Anatomy of a Deadbolt

Deadbolts are the most common type of lock you will come across. Their sturdy metal bolts and satisfying clicks give the impression of total security. These devices have been around since the 1800s and have never gone out of style. 

But the bolt is just one component of a deadbolt lock. Inside, there is a pin-and-tumbler mechanism. The mechanism interacts with the key, allowing you to open the door. 

Let’s take a closer look at the anatomy of a deadbolt. 

The Housing

This is the outer shell of your lock. It supports and protects all of the other parts of the lock. 

The Plug

The plug is the second biggest part of your lock. It’s the smaller circle within the house, where you will find the distinctive hole where you insert your key. This is also known as the keyway. 

The plug can rotate independently from the housing. This rotation is what causes the bolt to slide into place. The plug can only rotate when all of the pins are arranged into the sheer line. More on that below. 

The Keyway

Do you know how deadbolt locks have that jagged opening? That shape is called the keyway. 

Those little bits of metal run the length of the lock inside and guide your key and hold it in place. More on that in the “Anatomy of a Key” section. 

The Warding

The warding is the unique shape of your keyway. No two locks should have the same warding.

The Pins

Here is where the lock gets tricky, so pay close attention.

Above the plug hang several pins, usually about six or seven of them. They are held in place with springs. Each pin is divided into two parts. The top part is called the driver pin because it drives the lower pins into place with force from a spring above. 

The bottom part is called the key pin because they come in contact with the key.

The gap between the two parts of each pin varies in height. This randomization of height is what makes each lock unique and provides security. 

The Sheer Line

When all of the gaps of all of the pins are aligned at the same height, they are arranged in a pattern known as the sheer line. The sheer line is flush with the top of the cylinder, but more on that in a moment. 

The Cylinder

Hidden inside the plug is the cylinder. This is the heart of your lock. This is where the key sits inside the lock. The series of pins we talked about earlier runs through an opening in the top of the cylinder. Without the key inserted, these pins block the cylinder from turning. 

But when the key is inserted, the gaps in the pins form the sheer line, which aligns with the top of the opening in the cylinder. Now, the pins are out of the way, and the cylinder can turn freely, allowing you to open the lock. 

The Bolt

Where would a deadbolt be without its bolt? The bolt is probably the main reason why these locks remain so popular to this day. This solid chunk of metal looks very imposing and unbreakable.

When the bolt slides into place with that powerful “ka-thunk”, you can’t help but feel that your home is now an impenetrable fortress. 

And while it certainly does make the door hard to open, and the bolt itself is hard to break, the locks themselves can be picked easily. Don’t be fooled, these locks are not very secure!

The Anatomy of a Key

Keys: we take them for granted, don’t we? We’re always losing them, cursing them for being so tiny and inconvenient. But keys are a complex work of art! 

Let’s take a closer look at all of the thought that goes into your key. You’ll never look at them the same way again!

The Bow

This is the widest part of the key, the end that you hold on to and sticks out of the lock when the key is inserted. It’s a cute name, isn’t it? I guess they were more fanciful back in the 1800s. 

This is also where you tend to find important manufacturer information. It is also the best spot to mark your keys to keep them organized. 

The Blade

The blade is the long, skinny part that goes inside the lock. You could say this is the most crucial part of your key. Of course, you wouldn’t be able to get the key out of the lock without the bow!

The Shoulder

If you look at the spot where the blade meets the bow, you may see a raised bump on either side of the blade. That’s the shoulder, and it keeps the key from going too far into the lock.

Not all keys have a shoulder. Some keys simply bump up against the far end of the lock once they have been inserted too far. 

The Tip

The tip of the blade. Some keys have functional tips that provide additional security by interacting with a part of the lock. But in most cases, they’re just that: the tip. 

The Cut

You may have noticed the long, even groove that runs along the blade of your keys. That’s the cut. If you look at the opening of your locks, you will see that there is a bit of metal that catches on the cut of your key. That’s the keyway we talked about earlier.

This makes sure that the key sits at the perfect height inside the lock and is level all the way through. As we saw above, getting the pins perfectly level inside the lock is essential to getting your lock open. 

The Bitting

Also known as the teeth, these are the sharp metal bumps that run the length of the blade of your key. You could say these are the stars of the show. Each key has a unique pattern of high and low “bits” that correspond to the height of the pins inside the lock. 

The bitting is kind of like the secret password that opens your lock!

Putting It All Together

When you insert your key, the height of the teeth of the key plus the height of each pin comes together in such a way that the gap between each driver and key pins comes to rest at the same height. This even arrangement of gaps is known as the sheer line. The sheer line is flush with the top of the cylinder, which is housed in the plug.

The plug is now free to rotate within the lock’s outer housing, driving the bolt in the desired direction!

What About Skeleton Keys?

There is a persistent myth that you can get a hold of a “skeleton key” that will open many different doors. This may have been true before pin-and-tumbler locks became standard, but they are a thing of the past now. 

You will only find skeleton keys, also known as master keys, in use at businesses that use many locks like a hotel or a locksmith. These locks rely on unique warding systems rather than pins, and the skeleton key can bypass any warding. 

That said, most of these businesses are switching to electronic key cards, which are much more reliable and secure. 

Skeleton keys are a memory from the days of lever-based locks. This is where we also get the classic “keyhole” shape, the circle with the triangular bottom attached. You never see keyholes that look like this anymore except on vintage furniture. 

Lever locks are much simpler than pin-and-tumbler locks. 

So unless you have a very, very old lock, you don’t need to worry about skeleton keys. 

Upgrading Your Lock

If you read through this article and found yourself thinking, “Hmm, now that I know how my locks work, they seem easy to pick,” you would be right! With a little practice and the right tools, deadbolts are easy to open without a key. 

And the tools aren’t hard to find, either. You can buy them online in a few seconds and you don’t need any kind of special license or permit to get them. 

While it’s nice that most people seem to get by fine with a traditional deadbolt, you may want to upgrade to something more secure. An electronic lock has no keyway to be picked, but they can be expensive. 

Check out this article if you think it may be time to upgrade your locks. 

Next Steps: Call a Locksmith

If you have read this far, it is a safe bet that you have developed an interest in home security and/or the world of locksmithing. If so, you probably have the sense that it is high time to get some new locks. Those old-timey deadbolts are the absolute bare minimum of security. 

Some would say they aren’t even that. They are just the illusion of security!

That’s why you should get in touch with a locksmith. These professionals have to open hundreds of locks on a regular basis, so they know from experience which ones put up a fight and which ones crumble with the slightest pressure. 

They can help you find the right lock for your home and your budget, and explain how the locks will keep you, your loved ones, and your possessions safe from harm. 

Give us a call today. We will answer all of your lock-related questions. We are passionate about what we do and look forward to hearing from you!