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
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.
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