Recently moved to a gym that uses padlocks for locking your stuff, they sell them too for an inflated price of 3.5$, jokingly I tried my key on a friend’s lock, and one more random one, of course it didn’t work and it made me curious.
My question is how do factories make all keys/locks different even at these cheap mass produced kinds that are probably sold for 0.5-2$, how is it worth for a factory to “use different patterns” at that price, or how do they do it?
In: Engineering
Typically they’ll have sets of parts that are similar but different. For locks, it usually ends up being having either different sized pins, like you’d find in tumbler door locks, or different holes or notches in a plate as you’d often find in pad locks.
Key notches are generally numbered based on depth, so you could mass produce everything, and then just set up different combinations for different keys. And they do reuses patterns. You can usually find set of ‘keyed alike’ locks in the same box so you can get locks that all use the same key for convenience. So they could do runs of each key and then just distribute them in a way that allows people to find matches, but also not end up with everyone getting the same key.
They aren’t all different. Take a common door lock and look at the key. You may see five bumps and dips. Those push pins in the lock into the correct place to open it. Say each one has five height possibilities that properly set the pin to open. You have 5^5 possible combinations, or 3,125, but a bit less in practice since you won’t see keys with long flat areas on them.
More ridges on the key and more height possibilities means more combinations. But don’t think more pins means a lot more combinations because it could be 8 pins with only 4 heights, so only about 900 more than the 5 pin key, or less than a 6 pin 7 height key which has nearly 300,000 combinations.
The thing is more pins means more cost to make the lock. More height variance means having to deal with more different-length pin segments, and often requiring better tolerances, which costs more.
The same is true for cars. Older Fords had only a few hundred combinations. There have actually been cases of people accidentally driving off with the wrong car because their key fit, and it was the same color, model, and year as theirs.
Some things do repeat, or are at least close enough to work. We found out at my work that the key that operates our Stacker, also opens a security cabinet. Still not sure why someone tried that, but it works. Also, I had a padlock for my locker there that opened another padlock that was used there as well.
Wait until you discover that all Caterpillar, Kubota, Bobcat etc equipment use the same key for each brand. Some of the more modern stuff needs a 4 digit pin on the screen but the majority….
You are getting told that there aren’t a lot of different permutations for each lock model produced, but there still are maybe 100-200 per model. I think you’re still asking about the manufacturing process though, which I don’t think anyone has answered.
I don’t have direct insight into this, and I’m sure each manufacturer does it differently anyways. But this type of system can be automated. Lock manufacturers don’t have a separate mold for each key. They can either buy key blanks from another company, or make their own. Then they mill down those blanks themselves (or even have that process done by someone else).
Say they have 200 combinations and they want to make a manufacturing run of 10,000 locks. (Made up numbers.) Thats a run of 50 keys per combination. They set up the machine for combination number 001, run it through 50 times, and put all those keys into bin number 001, to get bundled with locks in lock bin number 001. Then they change the milling instructions slightly and move on to bin number 002.
This process can be automated. The instructions for the machine to mill position X on the key down to setting number 1 are trivially different than milling position X down to setting number 2. For example, you could tell the milling machine to increase the value for position A by 1 every 50 keys, position B by 1 every 150 keys, position C every 450, and so on. If you had 5 positions with 3 values each, and 50 keys per combination, this would lead to 50 x 3^5 = 12150 keys you could make. You would probably skip every combination that results in the key looking like a straight line though, because your customers wouldn’t trust that key.
Again I don’t have direct insight into this process, and every company would do it differently depending on their manufacturing processes and capabilities. But unless the runs are really big, they probably aren’t stamping them — like you said, it wouldn’t be worth it to set up that many patterns. But a milling machine in a tool and die shop can whip through thousands of pieces pretty quick (way quicker than a regular key making machine can), so they don’t need to have separate patterns.
Back before you could computerize the milling machines, the ones used in key manufacturing were probably a little more specialized, and someone may have manually increased the milling value after every 50 keys or whatever. Maybe just a series of knobs on the machine and a counter that would tell you how many have went through. But again, I don’t have first hand experience — I’ve just seen a few tool and die shops running, and I’m going based on that very loose knowledge to extrapolate into key making. There’s probably some video somewhere on YouTube that shows how one of those companies makes their keys. Keys are typically brass, so milling them isn’t as hard on your machines as something like stainless steel.
Our lockers at high school all had padlocks. Plenty or people had keys that opened multiple lockers
The simple fact that that’s the only way they are worth buying.
They are all the same, but assembled slightly different.
[This](https://www.google.com/search?client=firefox-b-1-d&q=how+to+change+tumbles+in+doorknobs#kpvalbx=_OSjVZfGZJdPm5NoPpeePSA_34) is how to change the locks on a typical doorknob, it’s built at the factory in the same manor.
They don’t. Which inevitably leads to the question of why or better, why aren’t they making them that way instead?
And it’s because the point of a lock is just to make sure that it’s not likely for some other random person that happens to want to rob you would have a key that fits. Which is easy enough to do.
Robbers don’t spend time to go through 1,000 keys to get into your door. Because it only takes a few minutes max to pick a lock, often seconds by someone determined. And most of those locks can be broken with a hammer or wrench pair or another lock. And not only that, but the door is only so strong as well and can be bypassed, so can the window.
So the locks only need to be different enough to discourage attempting to use random keys to open the lock.
If you want security beyond that, you need to step up security measures in many other places first.
If you buy a cheap lock from the dollar store. I think they have maybe 20 or so different variations. It’s definitely possible to go around a gym locker room and unlock the crappy locks with the same key
Watch some videos by the Lock Picking Lawyer on YouTube.
You’d be surprised how insecure almost all common locks are. Some of the major lock manufacturers are egregiously bad.
So to answer your question, they aren’t and they aren’t all that secure even if they were.
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