How does a Combination Lock work?

– [Narrator] In this video,
we’re gonna use 3D animation to show the inside of a combination lock. I’m gonna go over exactly why putting in a three-digit combination
allows us to open the lock. Let’s check it out. (electricity crackling) This video is sponsored by CG Boost. Stay tuned at the end of this video to discover how you can
create your own 3D animations using a free program called Blender. (upbeat electronic music) During most of my teen years, I used a combination lock at
school to open up my locker. Before making this video, I really didn’t understand how it worked. So I did some research,
looked at a few patents, and then opened one up to
see what’s on the inside. Let me show you what I learned. (bright music) Here’s the case that
holds all of our parts. This metal curved bar
is called the shackle. It won’t come out until the
right combination is put in. Then, it pops right open. This piece is called the lever. It slides right onto the bar here. The lever can rotate counterclockwise. This piece of metal wants to flex outward. Once it’s bent inside of here,
the tension makes the latch want to spring back to
its original position. Normally, the latch would just keep going, but the rotation will be
stopped by this tiny bump. The lever also has a tiny latch here that is spring loaded from the inside. The shackle comes down,
pushes the latch in, and then the latch fits
right into the groove, and we are locked. When the shackle is pulled out, the latch is forced to rotate to allow the shackle to
come all the way out. Then, the lever springs back into place. Let’s watch that again. The shackle can’t come all the way out because of the shackle collar. It guides the shackle
as it slides along here. But it stops us once we hit the very top. Okay, the reason that the
locking mechanism works is that, if the latch can’t rotate, then the shackle won’t come out. This is where the three
cams come into play. Let me show you. The back place has a bar sticking out. It holds the three cams,
washers in between, and a spring at the end. The spring ensures that the three cams and the washers are all pressed together. Cam two and three can spin freely. But cam number one is
actually attached to the dial. So when the dial spins,
this cam spins too. This is what it looks
like al put together. Each cam has an indentation in them. The lock will open when all
three of them are lined up. You can see how the lever can now rotate, which allows the shackle to open. When these three indentations
are not lined up, the lever can’t rotate, which means the shackle can’t come out. So how do we line up the cams
by only turning this dial? Let’s look a little closer. Each cam has at least one of
these teeth sticking off of it. You can see them better
from this point of view. If we turn cam one far enough, the tooth on cam one will
contact the tooth on cam two. And then if we keep turning,
all three cams move together. In fact, this is the first
step to opening up the lock. Let’s walk through this
process on the inside. This time we’re looking
at it from the front, so all three cams will
need to line up here. We turn the dial clockwise
three times to clear it. All three cam teeth are
in contact with each other and move as one. Now let’s keep turning the dial until we hit the first
number in the combination, which in this case is 21. Notice how cam three is now lined up right where it should be. Now let’s work on the second
number in the combination. This time we turn counterclockwise
one full rotation. Watch as the teeth from cam one come in contact with came
two on the other side. Notice how this doesn’t touch cam three, which is still right where it should be. Now we keep spinning the dial until we hit the second
number, which is 34. Now cam two and cam three are lined up. For the last number in the combination, just rotate the dial clockwise until it lines up with the third number. And there we go. All three cams are lined
up, the lever rotates, allowing the shackle to come out. As the shackle is pushed back in, it comes down with a bit of a jolt, which is usually enough to
nudge the cams out of alignment. This means the lock won’t
open a second time for free; you’ll need to use the correct
combination once again. (upbeat electronic music) The animation that you’ve just seen is created with a program called Blender. Is use Blender to create
all of the animations on my YouTube channel. And yes, the program is completely free. You can even download it
right now if you want to. However, it takes some
dedication to learn, and you’ll need a good teacher. Let me introduce you to my
friend Zach from CG Boost. I’ve been following his
channel for years now because he does amazing work, and I’ve learned a lot from him. Recently he’s released a new course called Blender 2.8 Launch Pad. Check it out at The course takes you
from the very beginning; you don’t need any prior knowledge. You’ll learn the fundamentals of Blender’s tools and interface, which you’ll then use to
create this car animation. After completing the course,
you’ll be able to create almost anything you
can imagine in Blender. I have personally watched
the entire course, and I can highly recommend it to anyone wanting to learn 3D animation. Remember that Blender is free. And this course by CG Boost is only $59. Plus the first 100 people to
use my link will get 20% off. Just go to (upbeat electronic music)