On the outside of the safe, it seems that only a dial is present, but looking further from that dial is an intricate locking mechanism, similar to a well-oiled machine. Attached to the dial at the exterior of the safe is a small cylinder known as the spindle. Whenever you turn the dial a certain way, the spindle follows in the same direction. The spindle is then connected to a drive cam, which also turns with the dial and the spindle. A drive pin is also attached to the drive cam and turns the wheel as well. Simply put, When you turn the dial, the whole locking mechanism turns too.

From this drive pin, it also turns the wheels or tumblers in the safe, which are located around the spindle. These wheels correspond to every number in your combination. So if you have a five-number combination lock, it means that your safe has five tumblers or wheels. Once you know how the locking mechanism of the safe works, then you’ll realize that attempting to open the safe without knowing the right combination is nearly impossible.

Sure, opening a safe without knowing the exact combination of numbers isn’t exactly impossible, but it sure is difficult, as any locksmith would attest to. In opening your safes, some locksmiths utilize special devices to listen to the locking mechanism of the safe inside while turning the dial, which could be related to a trial and error method. Some, however, actually just use a stethoscope to listen to the noises or clicks. Why do they use these kinds of tools, you ask? The logic is simple.

Good hearing is your strongest weapon when it comes to unlocking safes in this way. Turning the dial allows you to pass through all of the numbers in the circumference of the combination. When you’re doing it the right way, you’re going to hear clicks at or near the numbers that are actually part of the combination itself. However, this method is very susceptible to lots of mistakes, and people who attempt to do it when they have no idea what they’re doing or don’t know what sound they should look out for will only end up spending a long time and giving up midway. In many cases, someone who isn’t trained to unlock safes properly will hear internal noises that could throw them off. However, seasoned locksmiths utilize other techniques, like drawing graphs in order to determine which combinations work. 

When you try to do it yourself, you might be able to come up with multiple combinations, but none of them work most of the time. When this happens, you’re stuck to redo the irksome process of trying to hear sounds all over again, or slightly modify the combinations you currently have and use numbers near what you originally used. This could result in over a hundred combinations in attempting to lock the safe, and if Lady Luck doesn’t have your back, the safe won’t open at all.