Scientific Paper on bumping

[mh]

Probably interesting, didn't read through all the formulae yet:
http://jps.anl.gov/Volume6_iss1/Toporov.pdf

(I'm not the author, just found this on JPS.)

Cheers
mh

P.S. I like the Freudian slip at the end SCNR
P.P.S. No I don't mean "Burry".

[zeepia]

Thanks for sharing, I loved all those formulas

Ehem, remember to do your math before bumping, it gives you better results:

[mh]

It's interesting, but I'm not sure he got it right.

His model apparently assumes that only the driver pins fly away and are returned by the compressed springs, then he goes on with calculating the time the driver pins are on their way.

But I think the reality is different, the key pins will also move.
Master Lock once claimed to have high speed video proof that the pins fly away together and separate only on their way back.

Cheers
mh

[Legion303]

But I think the reality is different, the key pins will also move.

I think you're right, given how bumping works (i.e., not much like Newton's Cradle at all). Unfortunately I don't have access to a high-speed camera, and it sounds like Master hasn't released this video, only claimed they have it...

-steve

[PherricOxide]

They did release this animated video, but the accuracy of it is questionable http://youtu.be/Ip_z2-iiKvQ

[minifhncc]

But I think the reality is different, the key pins will also move.

That depends whether it is an inelastic or elastic collision...

[mh]

I think it essentially depends on the geometry of bump key, lock and pins.
It might be very hard to make so that the key's slopes do not move the key pins anymore after the initial 'bump'.

[ARF-GEF]

Could it have something to do with the material of the pins too?
For example hardened steel pins are pretty rigid while brass pins are a lot more soft by comparison.

Also: I've been wondering, if the springs in the lock have very much different strength doesn't that mess everything up?

BTW mh, looks like and interesting paper, thanks for sharing!
(The math looks horrendous for me, but I will do my best toget myself to read it. )

[jos weyers]

They did release this animated video, but the accuracy of it is questionable http://youtu.be/Ip_z2-iiKvQ

if those pin-chamber sizes are accurate, they're asking for a overlift attack.....

[fgarci03]

It's interesting, but I'm not sure he got it right.

His model apparently assumes that only the driver pins fly away and are returned by the compressed springs, then he goes on with calculating the time the driver pins are on their way.

But I think the reality is different, the key pins will also move.
Master Lock once claimed to have high speed video proof that the pins fly away together and separate only on their way back.

Cheers
mh

I'm no bump expert, so the veracity of what I'm saying is questionable.
But I don't think it's that. I may be confused, but I think that I've seen bumping a lock with the driver pins on the bottom. Like when you use your key with the bitting pointing down. So that way, if it's true that all the pins fly away, there's no way that the key pins return to their position sooner than the driver pins.

And even by doing it with the bitting pointing up, the driver pins are pushed by the springs AND gravity, so on their way down, they would actually be faster than the key pins, thus pushing them down together, because those are only affected by gravity.

[mh]

Well, if one thinks that (elastic) collisions are a good model for what's happening when bumping, these would (also / at least) happen "at the end of the bible", so to speak.

Other opinions say that the pin holes are not straight when tensioned, and that the driver pins would stop at the shear line because of the tensioning.

Cheers
mh

[tacit_guardian]

Link was broken when I tried it, but a little digging around and I managed to find it. Paper is " Lock Opening by Bumping: Physical Analysis and Secure Lock Designs" by Alexei Toropov, Ph.D.

There are some very interesting points in this article that I'm going to have to take into account. Thanks for the paper reference!