(Disclaimer first: I’m not asking this because I’m planning to do anything illegal and need the information for it, I’m just curious.)
There’s a popular movie commonplace about a good or a bad guy getting temporary access to a key they’d need. They would take out a box filled with wax or some similar substance, impress the key into it from both sides, and use this mold to copy the key.
My questions:
Does this actually work, or has it ever worked with lock technology now out of use?
If yes, then:
What is this substance? Wax?
What would the actual procedure be? Would they pour some liquid into the wax mold, solidify it, and use the resulting negative of their impression as a copy of the key? Or is there more to it?
The Jackal does this in Fred Zinneman’s film The Day of the Jackal, but he never uses the mold – when the time comes, he assaults the hotel manager and just takes the originals. He seems to use a small “tin” filled with clay or plasticine (not wax, as far as I can tell). Maybe he just wanted to be ready in case the keeper wasn’t there.
I suppose you could use a clay mold to cast a metal key, but I’d be suspicious of its strength. It seems to me a better use would be to cast a plaster replica, which you could then use as a guide in machining a key blank to the correct configuration. Then there wouldn’t be any problem with strength.
However, I once made an aluminum key in Metal Shop by making the impression of the key in the sand molds we used for making belt buckles. It did not work well and took a lot of filing but I was able to get a usable key out of the process.
I would WAG that the wax indent gives them the key shape and allows them to either hand file a key to shape from a blank key stock or pour a mixture in that will harden without melting the wax and then use this duplicate but soft key to make a key imprint in a sand mold for bronze pouring.
Yep. Another way this can be done is by laying the key on a damp sheet of paper and sprinkling graphite on it, leaving an outline of the key from which you can file a blank.
In practice, I’ve never seen this done. Most locks are either so easy to bypass that filing a key would be unnecessary or have features that require specialized blanks and other features that make this inadequate.
It was used in the BBC adaptation of ‘Gaudy Night’ by Dorothy L. Sayers. I think it could more easily be done with the old-style ‘skeleton key’ than with modern keys.
They showed a good example of it in the movie ,the great train robbery. Safes or lock boxes used keys at the time, rather than combination locks that are used now.
I would think that the purpose of impressing the key in a soft substance would be to get the tooth pattern.
When I take a key for duplication, the key shop has a rack of blank keys divided according to brand. The worker selects one with the same narrow profile. (Mine, here, looks like a fancy question mark. “?”)
Then all the worker does is cut the tooth pattern using a duplicator.
So you make a clay impression and make sure you notice what brand and the narrow profile. (I would have pressed the clay into the keyhole of the lock to get that, since I am not a trained locksmith.) Then you get a blank for that brand that matches your keyhole impression and file it down to the tooth pattern.
It’s not just the teeth, but the grooves that need to be right. Keys at a locksmith are sorted according to brand and series. The teeth in most keys are set either right or left in a random pattern, and at different depths. Medico keys are set left, right and center, making the locks nearly impossible to pick.
The material of choice is often cuttlefish bone. It takes a good impression but is also robust enough for the process afterwards. I understand the drawback of using plasticene is that you have to take a cast, make a negative and then make your key.
With cuttlefish not only do you get a very accurate impression, but you can go straight from the cast to the final.
Given that common & garden lever based locks generally have a wideish tolerance so are pretty easy to foil (especially the 3 level kind), I don’t think it would make good sense to post a how-to here.