Golden (bump proof) pins

bump proof?

For a long time Han and I are doing tests for various lock manufacturers. At the beginning, most of the requests were concerns if the ‘bump proof’ pins they came up with were really bump proof. And most of the time they were not.

On average it took three rounds of testing (and back to the drawing board) before we could not bump open the lock anymore. In some instances we supported the manufacturer with some technical advice to really make the lock bump proof (or highly bump-resistant).

And of course we have been thinking about designing our own bump-proof pin. We labeled it ‘the search for the golden pin’.

In our view, the golden pin has to have (at least) the following properties:

1) Prevent bumping one hundred percent (bump-proof, must withstand ‘advanced bumping’)
2) If possible, make other kind of attacks more difficult (like picking, impressioning and decoding)
3) The solution must contain not too many parts and must be easy to manufacture
4) Easy to Add to a classic 5 pin tumbler lock without modifying the core or house (too much)
5) If possible the ‘golden pin’ must be implementable in dimple and or other pin-tumbler style locks
6) Free of patents

Han and I have been partly successful in this search. And still we are having new ideas and brainstorm/try out sessions on a regular basis.

But ever since our trip to Vienna, our way of looking at the problem has changed.

We learned that if you ever want to have your invention implemented by a lock manufacturer, stop searching for a ‘golden pin’, and start searching for a ‘golden key’!

That is right, lock manufacturers are under constant pressure to come up with new patents on keys. A ‘patented key’ is required in all serious projects, and when a patent is ‘end of life’, so is the commercial success of the lock. Or actually a couple of years before the expiration of the patent (after all, who wants to buy something that will lose it’s ‘copy protection’ in three of four years?).

In a way it is a very healthy system. It keeps lock companies innovative. They can not just design a lock once and live of that design for ever. It forces them to keep investing in engineering.

The flip side it that great locking systems all of a sudden become ‘worthless’ because of the patent expiration. And in some instances that is not fair if you look at the level of security the lock and keys are still providing.

Looking at our mailbox, we are not the only ones looking for the golden pin….

A couple of times per month we receive mail from people who came up with pins or solutions against bumping. In almost all cases the six above properties are not met.

One of the last mails I recently received was from a gentleman called Ian Cecil from Australia. His invention is somewhat smart and makes use of the ‘floating pin’ principle. With that I mean that one of the pins is not reaching the ’9′ position. We have first seen this solution in CES locks where they simply did not drill the hole in the plug all the way. And other floating pins can be found in systems like GeGe Pextra, Nemef and Master padlocks.

But before I take you to all the solutions we found in various locks, back to Ian:

Ian cam up with the following idea: Use a short spring that is connected to the ‘stopper plug’ and the ‘bottom pin’. And the bottom pin is by magnetic force attracting the top pin. If you keep the top pin small (0-3), the bump key can not make contact and obviously does not work. As I said, a nice invention but far from ‘bump proof’. The lock can still be opened by ‘advanced bumping’.

How does advanced bumping works? If I know there is a floating pin inside a lock, all that is required is a set of probe keys to determine the position and minimum depth of the floating pin. And once that info is decoded all I need to do is cut a 99949 key and open the lock.

Still, Ian makes a lot of sense on his website and shows he does know what he is talking about. Who knows, maybe he will come up with a ‘golden key’ one day ….

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54 Responses to “Golden (bump proof) pins”

  1. mh, possible, but the upper pin should get more energy (thus speed) than the bottom, because if they travel the same speed, they will not separate :) But as you said, possible situation.

    Schuyler, mh, Barry, whoelseiscoming, we’ll see there if you guys buy my tools ;)

  2. One thing to note about the Newton’s Cradle analogy is that by the mathematics of elastic collisions, perfect momentum transfer from the lower to the upper pin only happens when the two pins have equal mass. If this is not so, then the lower pin continues in motion. In particular, if the top pin is lighter, the lower pin continues up with it (but at a lower speed than it), while if the top pin is heavier, the bottom pin rebounds back towards the bottom of the lock (where it immediately hits the bump key again). The bottom pin is only left motionless if its weight is equal to the weight of the top pin. In the Newton’s Cradle, all the balls have the same weight, making for near-perfect momentum transfer; but in locks, top and bottom pins have different weights.

    The math of elastic collisions isn’t a perfect way to model a lock, but it’s a good first step.

  3. Ian Cecil says:

    In trying to prove my bent hole theory i may have overlooked the obvious. (sort of):(
    Here’s why.

    When i was looking at the pins when bumping there was no separation as in Newtons cradle(that i could see). It looked like the bottom pins were just bouncing the top pins up and the bottom pin couldn’t go past the shear line.

    But actually i think i got it upside down.
    what is happening is that
    when turning pressure is applied to the barrel
    1. The top pins bind.
    2. The bottom pins bump the top pins above the shear line
    3. The top pins want to fall back down but cant enter the barrel because the cant fit.
    The Top Pins cant possibly fall back down because the barrel has turned just a fraction more from where it was when it was binding. So there is no round hole to fall back into.

    The Newtons cradle theory is great but has flaws. Put a spring on the end of the last ball and see what happens. All the balls stop dead. Because the top pin binds in the lock the spring has no effect.

    The important bit is that when you are bumping a lock the top pin and bottom pin don’t have to separate as in a newtons cradle. The top pin just has to be pushed above the shear line. In fact i would say the bottom pin acts more like a hammer. It has to overcome the friction of the binding top pin & push it above the shear line.

    Spool pins work same way, no difference. (unless it is the last one to be pushed up??)

    Locks with tighter tolerances and better machining are likely to have the top pins bind at the same time? Hence only 1 hit is necessary. The only randomness is caused weather the top pins all bind at the same time or not.

    I made a large pin chamber, top pin and bottom pin to test the theory and see what was happening. I will take a video and post it when i can.


  4. John says:

    Has anyone tried adjusting the top pin size to complement the bottom pin size? That is say if a Kwikset had a bitting of 2 5 3 6 4, then use pin numbers 6 3 5 standard-top-pin, and 4 for the top pins (perhaps filing down the bumps to a flat surface on those larger top pins and perhaps cutting slots for them to false set as if they were spool or serrated. The differing masses and spring compression should confound the lock bumping a fair bit. If the working mechanism is purely the top pins binding and not reentering the plug cause they basically set as the plug is under tension then the false sets from security pins should help unless the energy is so sudden as to skip over the false sets. I’d like to see an experiment to see if spool and mushroom pins would false set during lock bumping.

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