Most banks relied on small iron safes fitted with a key lock, then when the gold rush hit in the middle of the 19th century unsuccessful prospectors turned to robbing banks. The robbers would break into the banks and then smash a window and carry the safe out of it (the safes did get to room size until later on), they would then just smash the lock using a pickaxe and a hammer, this was normaly done at a safe location were they had a bit of time. Banks then demanded more secure safes, both larger and stronger, but they still only used a key lock to secure them, which was circumvented by either smashing the lock or by poring gun powder in and blowing it open. So in 1861 they introduced the combination lock, banker quickly adopted this lock for their safes, but robbers came up with ways to get past it. It was possible to use a lot of force to punch the combination lock though the door, others used drills and mirrors to see where the groves lined up with the mechanism. A more direct approach was taken up too, the robbers would kidnap the bank managers and force them to reveal the combination. Time locks become common place after the 1870’s (to reduce kidnappings of the bank manager) this stopped a lot of night jobs (not many outer country vaults got these, but every new vault (built after the introduction of the time lock) go them). This forced thieves to come up with new ways of getting in, they resorted to prying open a small gap between the wall and the door (where the hinges are) and they would then pour in gun powder and blow the vault open, this forced vault designers to make a staggered hinging system, this was circumvented by using liquid nitroglycerine (gotten from boiling dynamite in a pot of water and skimming it off of the top, it was more unstable in this form but a risk worth taking), which they would pour into the gaps that they could make and then set off a fuse to blow the vault. The doors were then redesigned with a smooth, thick, tapered plug that they door would close with; the plug was so tight that the liquid nitroglycerine wouldn’t be able to fit in.
By the 20’s, most banks stopped using safes and went to gigantic heavy vaults with walls think enough to survive angry mobs, robbers, and natural disasters. Even with these new security measures the vaults were still vulnerable. The cutting torch (thermal lance) had become a bank robbers new method of getting into a safe, by burning oxygen and acetylene gas the cutting torch could reach temperatures of about 3000C, and this would cut though the steal like a hot knife through butter. Robbers use cutting torches in over 200 robberies in 1924 alone. They were easily gotten a hold of due to the Great War and many people were proficient in using them (both soldiers and civilians). The manufacturers of the bank vaults then switched to using a copper alloy in the vault doors, this spread the heat of the cutting torch out much more easily and prevented the vault from melting or burning. After this design many bank burglaries stopped happening, as the cutting torch was such a simple way to get into a bank vault that almost anyone could do it.
Bank vaults are a very large piece of solid metal with a variety of different locking mechanisms (the main one being a combination lock/multiple keys lock) which is then in front of a cadged off area (like a jail cell) which is normally a key lock to open.
Bank vaults are constructed with steal reinforced concrete (reinforced concrete) and at a minimum of 1 foot thick, to door itself is typically about 3.5 feet thick.
here is a table for a random bank vault
here is a table for a random bank vault
Random bank vault table (for 1920s)
Vault lock: 1D6
1 – key lock
2 – combination lock
3 – multiple key lock (1D4 keys required)
4 – multiple combination lock (2+ locks)
5 – key and combination lock
6 – multiple key/combination lock (1D6, 1-3 keys, 4-6 combination)
Does it have a time lock: 1D6
1-5 – yes
6 – no
Is it made of steel or copper alloy: 1D6
1-3 – copper alloy
4-6 – steel