A lock that purposefully breaks on picking attempts?

[Hippo_vibrations]

So, in the spirit of daydreaming about cool lock constructions, I started to think about building a lock whose purpose is to seal itself if it 'detects' a suspicious entry attempt. I'm mostly thinking of some diplomat's safe for whom it's better to have access temporarily denied to some documents instead of having them in the hands of a spy.

So from the outside the lock would seem like a standard pin-tumbler lock, opening when a correct key is entered and turned 45 degrees. But in the lock we would have a secondary collection of driver pins that align with the pins when the key has been turned 15 degrees. And these driver pins would have some kind of one-way movement design such that if they ever lower into the pin-holes, they cannot be raised without full lock disassembly. (Think fish-hook style serrated edges or spring loaded horizontal pegs or something.) With the correct key entered these would not lower themselves into the cylinder, but a picked or a bumped lock would jam at the 15 degree mark. To forbid impressioning attempts the first-level driver pins could be made of some material, say tempered glass, that would have a strong compression strength but very low resistance to shearing.

How does such a thing sound? I'm guessing an industrious picker with foreknowledge on the lock structure would pick the lock, turn it 5 degrees and read how high the pins can be lifted to work out a copy of the key? (Maybe a groove running between the first and second set of driver pins where a pin can be over-lifted to trigger some other problem...) More generally, are there such self-sealing locks generally available or is there another approach generally considered to be more viable?

[femurat]

Are you aware of trap pins? The first example that comes to mind is the evva dps but there are others.

Cheers

[RedStagKiller]

https://www.youtube.com/watch?v=7d4Leve0cfs

[Hippo_vibrations]

So not only is my idea plausible, it has already been done but with better design and structure than what I was thinking about

Thanks for the link and the terminology, guys!

[Robotnik]

The glass intermediate pins are actually an interesting idea, not one I’ve heard discussed before. There’re a couple problems I could see that would have to be worked through, though.

The tolerances required in a pin-tumbler lock present some issues; glass being a noncrystalline solid, machining it - especially to a cylindrical shape - is orders of magnitude more difficult than forming soft metal like brass. Additionally, the tempering process distorts the glass itself to some degree, so even if glass were formed to exact spec (no easy task), tempering would change its shape and size. I’d see more potential for success in using annealled glass rather than tempered, and grinding it to spec.

This would be a materials- and labor-intensive process, so I’d wonder about whether the effectiveness of these pins would justify the investment. As far as using glass pins, I don’t know if I see it. Even if the pins shear under impressioning forces, I don’t see this stopping the lock from being impressioned, and may in fact make it easier. What I could see working well is using glass in some other element of the cylinder that would shear under excess force and block plug rotation, but this brings up the issue of when excess forces are applied during normal use of a cylinder (i.e. with a poorly cut key or an inadvertently inserted incorrect key).

Like I said, I do think this is an interesting idea, so I’m curious to hear others’ input as well.

[Hippo_vibrations]

The glass intermediate pins are actually an interesting idea, not one I’ve heard discussed before. There’re a couple problems I could see that would have to be worked through, though.

The tolerances required in a pin-tumbler lock present some issues; glass being a noncrystalline solid, machining it - especially to a cylindrical shape - is orders of magnitude more difficult than forming soft metal like brass. Additionally, the tempering process distorts the glass itself to some degree, so even if glass were formed to exact spec (no easy task), tempering would change its shape and size. I’d see more potential for success in using annealled glass rather than tempered, and grinding it to spec.

This would be a materials- and labor-intensive process, so I’d wonder about whether the effectiveness of these pins would justify the investment. As far as using glass pins, I don’t know if I see it. Even if the pins shear under impressioning forces, I don’t see this stopping the lock from being impressioned, and may in fact make it easier. What I could see working well is using glass in some other element of the cylinder that would shear under excess force and block plug rotation, but this brings up the issue of when excess forces are applied during normal use of a cylinder (i.e. with a poorly cut key or an inadvertently inserted incorrect key).

Like I said, I do think this is an interesting idea, so I’m curious to hear others’ input as well.

Thanks for your thoughts! One big thing I lack is metalwork experience, or machining of (small) parts in any material. "Just make the pieces smaller and shaped like a small cross" or "just make the pieces out of glass" are ideas easy to say but I have very little idea where a project turns from being slightly more challenging to completely unworkable.