Possible simple defeat for bumping?

[digital_blue]

Well, for the record, I think the idea of carrying a set of 5 or 6 bump keys for each lock isn't very practical. You guys are still thinking like WE think, but if it were one of us, we'd just pick the freakin' thing and be done with it.

UWSDWF had the right idea. You can call it security by obscurity if you like, but someone would have to

a) have a reason to expect this tactic was in place
b) have enough wherewithal to prepare for this tactic

The reason that bumping is any real threat at all is because of its simplicity and ease of use. I'm not saying this would turn a Kwikset into a Medeco here. But it's just one thing that could prevent bumping. Simple as that.

Regarding the failure rate... I keep going back to this because I still see this as the only possible big hiccup in the whole thing... what I want to know is, based on what do you think this would lead to failures? I understand the *idea* that it could... what I want to know is (and I honestly don't have an answer here...) WILL it? In the real world. Is it not true that most often, a lock with a broken spring will continue to function uninterrupted for a long, long time?

Since this point is the real stumbling block, I'm trying to get something more substantial than an assumption that it wouldn't work.

Lockies in the field? Is it common for a pin tumbler lock with a broken spring (installed in the typical config, that is) to lead to a failure of the lock? If not, is that because springs never break, or because it really doesn't matter ALL THAT much most of the time?

db

[EricM]

you could always add a ball bearing to any of the tops of the pin stacks and that nullifies the attack. plain and simple. that doesn't interfere really with anything as long as it's small enough.

[Bud Wiser]

digital_blue - I think your idea would stop 11 year old girls from bumping for sure

[Dent]

With the cheapness of medaco and other hard to pick(and unbumpable) type locks, if you are really concerned with it, just install those locks.

I mean you would already have to take apart and re-pin this to implement this solution, so at that point why not just install a medaco from the beginning?

[keysman]

UWSDWF had the right idea. You can call it security by obscurity if you like, but someone would have to

a) have a reason to expect this tactic was in place
b) have enough wherewithal to prepare for this tactic

The reason that bumping is any real threat at all is because of its simplicity and ease of use. I'm not saying this would turn a Kwikset into a Medeco here. But it's just one thing that could prevent bumping. Simple as that.

Good points.. I agree it would keep the 12 YO girls from bumping your lock

Regarding the failure rate... I what I want to know is (and I honestly don't have an answer here...) WILL it? In the real world. Is it not true that most often, a lock with a broken spring will continue to function uninterrupted for a long, long time?

Yes ,it may be a long time before you find a broken / bent spring.

Lockies in the field? Is it common for a pin tumbler lock with a broken spring (installed in the typical config, that is) to lead to a failure of the lock? If not, is that because springs never break, or because it really doesn't matter ALL THAT much most of the time?
db

It wouldn't really be a problem if 1 spring out of 5 or 6 was missing or bad.. all the springs missing or bad .. well that is a different issue
Scheduled lubrication would probably eliminate 90% of any failures, a shot of any lube would bring it back to working condition after a failure.

[linty]

i like this idea, but without spring pressure it would only be a matter of time before that 9 pin didn't want to drop back down. a little bit of debris in the lock (from normal wear) could cause the 9 pin to stay in a raised position after you insert the proper key, causing lockout.

[Mememe]

Assume that bumping works on the theory that all the pins are moving at roughly the same velocity thus allowing a window of opportunity where the shear line is cleared in all the stacks at the same time.

Would having different springs in each stack (some softer some harder) not result in the pins moving at differentt speeds thus never having the full shear line cleared.

If this works, then it may be a better solution than compromising the locking as suggested above.

my 2c.

[Schuyler]

you could always add a ball bearing to any of the tops of the pin stacks and that nullifies the attack. plain and simple. that doesn't interfere really with anything as long as it's small enough.

um, just in case any of you didn't see that comment.

I had what I considered a pretty swank idea for an anti-bump pin tumbler lock, until I talked to EricM.

It bears some serious testing, but the ball bearing should take the energy transfer into itself and leave the driver pin in position.

[raimundo]

just thinking about DB's concept, i wondered why a top pin and spring would be a drawback to security on a 9depth pin, i guess its because the long pin would be thrown all the way into the top of the cylinder. then I thought that the nine depth pin could also do this better with serrations, if its keepin the lock locked, it must be caught between the plug and cylinder, then I got the idea that a zero depth pin would likely shoot the short distance to the shear line driven by the metal of the bump key, not just the energy, and this would force its bottom pin above the shear.
another concept that might work, would be serrations perhaps on the interior of the anti shim flange and fitting into other small serrations on the cylinder mouth, could lock together like gears when struck with a bump, while not being large enough to matter when the key is used by hand.
the physics of the nine depth pin, could be optimized by making the top pin as small as possible and the spring very weak, remember if a large object, (the long bottom pin) strikes a lighter object, the top pin and weak spring, not all the energy is transfered, and the heavier object continues moving, some of you may have tested this theory if you have been in a light car hit by an SUV

[zeke79]

you could always add a ball bearing to any of the tops of the pin stacks and that nullifies the attack. plain and simple. that doesn't interfere really with anything as long as it's small enough.

Brilliant idea !

So if one really wanted to, you could place a small master pin above the top pin and achieve the same results.

[EricM]

:: taps nose toward zeke79 ::

[digital_blue]

I'm not sure that would work. As Ray indicated with his SUV example, if the top pin and the master wafer (or ball bearing, or whatever) were less than or equal to the bottom pin, wouldn't they BOTH just hop above the shear line?

Take Newton's Cradle as the example. If you swing two balls, two balls exit the other side. Assume for a moment that the bottom pin could be viewed as the "two balls", based on mass, then the flip side would be both components hopping and the lock opening.

I've got an LSI meeting tonight and we'll do some tests, but I can't see it preventing bumping. We'll see.

db

[Schuyler]

I'm not sure that would work. As Ray indicated with his SUV example, if the top pin and the master wafer (or ball bearing, or whatever) were less than or equal to the bottom pin, wouldn't they BOTH just hop above the shear line?

Take Newton's Cradle as the example. If you swing two balls, two balls exit the other side. Assume for a moment that the bottom pin could be viewed as the "two balls", based on mass, then the flip side would be both components hopping and the lock opening.

I've got an LSI meeting tonight and we'll do some tests, but I can't see it preventing bumping. We'll see.

db

But it's a dramatically different scale. Even in the little executive desk-toy the reaction ends after a while, because energy transfer between solids is never perfect. However, if you were to replace the last ball in the chain with a smaller ball? The smaller ball would take the energy transfer and re-express it through an increased velocity.

I'm not saying that the driver pin wouldn't move, but the bottom pins move too, don't forget, which is why people have to file below the nines to begin with.

[n2oah]

How about we just throw a sidebar in it and call it a day?

[digital_blue]

Yes. That'll do just fine. Now how do I get this sidebar into my Kwikset?