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#21 Psilocybe

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Posted 16 May 2007 - 04:09 AM

I understand what you are saying (and the illustrations were easy on my brain at this time of night). I understand more about how the bump key works now, but what I was really getting at isn't covered in your post. To make this simpler, let me relate this back to Newton's Cradle.

So rather than picturing the standard 4-ball cradle, imagine a 3-ball cradle. The bump key is the first ball, as it makes the initial impact. The bottom pin is the second ball. The top pin is the third ball. So the question is, if you held the first ball in your hand, and forced it into the second ball until the second ball moved a bit, would the second ball stop in its tracks as soon as you stopped forcing it forward?

Honestly, I'm not completely sure. I would think that the second ball would still move a little more. I realize that if it does it must be minimally, otherwise the bump key wouldn't work right. This is what I was really wanting to know though.

Anyway, thanks for your patience. I'm really not trying to be an :furious3:hole.

#22 theopratr

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Posted 16 May 2007 - 03:53 PM

You're completely right, it wouldn't stop dead in it's tracks.

The magic of the bump key lies in a relatively small amount of effective force. The first ball of the three ball cradle being of small mass, or having a small amount of force running through it, running into the second ball of much larger mass, which in turn pushes the third, much lighter mass.

The greater the impulse force (think wrist action), the more cleanly the transfer will take place, and the less motion occurs in the second ball before the lock is bumped. This is caused by the fact that with the greater impulse the three balls tend to stay as one system of three for a shorter period of time, causing the third ball to spring away in less time with greater speed, increasing the chances that your cradle can be "bumped".

So, the cap to the logic is that you're not so much pushing the first ball with your hand as you are flicking it into place, forming the three ball system, and letting the third ball fly. If the force you use it too great, then both the second and third balls will move, and this is the failed bump. Most beginners attempts at bumping fail due to their using too much force, or force that is large, but lacks impulse. The key, then, to your answer is that the force applied to the key has to be a "quick tap" as opposed to a pushing blow, so that the energy transfer is clean and only the top pin moves appreciably.

As was previously stated, most bump keys are cut a bit deeper than absolutely necessary as to allow for some range in the amount of force used, so that even if it's a bit high, the bottom pins can still jump a little without ruining the bump.

I hope this approaches an answer to your question!

#23 Psilocybe

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Posted 17 May 2007 - 12:03 PM

This definately answered my question. By the way, the information in your last 2 posts here were very informative. I understand better how this all works, and I think this will help me to make (and use) better bump keys. I honestly think you should put that info in a new thread and sticky it. I believe it would help people immensely.

Thanks again!

#24 theopratr

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Posted 18 May 2007 - 01:00 AM

I'm glad this helped... the majority of my responses are written right before bed in the early hours of the morning, and thus I often worry that I make little sense.

I'm trying to compile a new bumping resource about the physics and theory that goes into making it work, but between work and school, I am too often left with not enough time for my hobbies!

And besides, as the media tells us every time they do a special on bump keys that absolutely everyone who is reading about and/or buying bump keys online is a crook. Clearly, they really don't care about the specifics of why it works, just how to use it to break into their rich neighbor's house.

I swear that I'm not bitter in the least.
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