h a l f b a k e r yMy hatstand runneth over
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Conventional cylinder locks can be picked in moments, even
by
an amateur, using a bump-key (aka pick gun, bump gun etc).
(Skip this para if you're familiar with locks.) In a regular
lock,
there are a series of pins that run through the body of the
lock
and through the cylinder (the part
that turns). Each pin has
a
split (gap) in it at a different height. The key just lifts all
the
pins to the right height, so their splits are flush with the
edge
of the cylinder, which can then be turned. The pins are
pushed downward with little springs, against which the key
acts to lift the pins.
(Skip this para if you know about bumping.) A bump-key or
pick gun is just a thin metal rod that slides into the keyway,
and a mechanism for giving the rod a small but very sharp
upward tap. This tap bounces the pins upward, and it's the
top half of each pin that bounces the most. As a result,
there's a fraction of a second where the top halves of all the
pins are all the way up, and the bottom halves are all low.
During this fraction of a second, the lock can turn.
(Welcome back.) Bumping would be much harder if the
movement of the pins were damped - it basically wouldn't
work. You can do this by putting heavy oil into the lock (it
will
still work fine with a key), but then you get an oily key each
time you use it.
So.
Instead of oil, just make the *top* half of each pin strongly
magnetic. You can already get tiny cylindrical rare-earth
magnets, so this would be no problem. The lock body is
normally brass or zinc - non-magnetic metals. As a result,
the
movement of the *top* halves of the pins will be heavily
damped by magnetic induction (just like the experiment of
dropping a strong magnet down a copper pipe). The
resisting
force will be greatest when the velocity is highest, meaning
that the "bumped" pins will only travel a very short distance.
So, this is a very simple-to-implement change that would
make
locks resistant to bumping, whilst leaving them just as
convenient to use.
https://pin.it/3dyqvgctaa6hya
Max's pride - now on Gumtree [xenzag, May 31 2019]
[link]
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I am not convinced this would have the desired effect. The eddy currents are only induced when the magnet is moving, so at the point of the initial bump there will be no resistance. Oil on the other hand has stiction and surface tension, in addition to the v^2 damping effect. |
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But I may be wrong, and it would be quite simple to try this out. |
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Oh, and another thing: would this not make it trivial to unlock, using a master key made of magnets that repel the pins? |
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If the tops and bottoms were both magnets then they would stick together and so the bump would not separate them |
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//at the point of the initial bump there will be no
resistance// Yes, but as soon as the bump starts, resistance
will be very high. |
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//using a master key made of magnets that repel the pins//
Hmm. Possible. But you'd have to overcome the spring
force, which is fairly high. Also, you could randomize the
polarity of the pins, necessitating 32 different master keys
for a 5-pin lock. |
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//If the tops and bottoms were both magnets// Also
possible. |
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How does a bump, produce momentum in more than one direction at once? |
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It works a bit like Newton's Cradle, where the impact of one
ball is transmitted through the intermediate ones, and only
the ball at the opposite end is sent swinging. Likewise, when
you hit the end of the inner part of the pin, it stays more-or-
less still and only the top part flies upward. |
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I think this would be secure right up to the point where
burglars realised they could lift the upper pins with a strong
magnet. |
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I don't think that would work. The magnet would need to be
held against the front of the door, above the lock, and would
be pulling the pins at an angle; I think they'd just stick. |
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(I have actually used a magnet to break into my own house,
but in a rather different way.) |
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You hit the window with the magnet? |
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If you din't actually break anything then technically it doesn't count as breaking in, I would of thaught. |
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No, I used the magnet to open a window latch. It was a
wrought iron latch, and a stupidly strong rare-earth magnet.
The same magnet, some months later, attacked my laptop
and physically bent the read-head in its hard drive. |
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You can use strong magnets to open most standard key locks. |
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Locks really only keep out honest people. |
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Some, not most. What you're doing with the magnet is
actually bypassing the lock (ie, releasing a lever that holds
the bolt, and which can normally only be actuated by turning
the lock), and it only works on certain deadbolt locks. At
least here in the UK, locks that you can bypass that way are
not the norm. |
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This won't prevent locks being picked. When you
pick a lock, you insert a flat piece of metal that
puts torsion on all of the pins, causing them to
bind against the sides of the shafts in which they
slide. The pick then forces them to lock into the
correct position one by one. No magnet is ever
going to be powerful enough to interfere with this
relentless process. Picking the average lock is
easy. Picking 'this' lock will be just as easy. Sorry
Max, but if this is your lock, I'll be in your house
within 2 minutes, then out again with your prized
collection of decorative crocheted pink toilet roll
covers and matching ties. |
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Uh, [xen], mon amie, can I suggest you read the actual
idea? This is not intended as a means to prevent picking. It
is intended as a means to prevent bumping. |
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Picking requires considerable skill, even for a regular 5-pin
Yale lock (which has at least two spool-pins to make picking
harder). Bumping requires a knack (if using a manual bump-
key), or almost no skill at all (if using an electric bump-
key). |
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Most burglaries happen through unlocked doors or windows,
stolen keys or by simply breaking something. A minority
happen through lock bumping. Very, very few happen
through actual lock picking, because why bother? |
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You're very welcome to come and try to pick any of my door
locks. They are regular Yales, except I put spool-pins at
*all* the positions when I re-keyed them. I should also
mention that unless you're a _very_ good sprinter, 2 minutes
won't even get you beyond the front hallway. |
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I've already been and gone! Check on Gumtree (pic
in link) Yale locks are a breeze. |
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I hadn't heard of spool pins before, so I Googled.
I weep for humanity.
Virtually every search result was about lock picking and how
to BEAT spool pins. It's a sad indictment on the society we
have become... |
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Society hasn't changed, locks only keep out honest people.
Honest people don't need locks.
Honest people don't need laws. |
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Honest people are WAY outnumbered... and majority rules. |
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Will it change the feel of inserting the key? |
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Perhaps chipkeys for houses will be the next big
thing. |
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But as a Russian guy once said, "Maybe the lock
makes it a two-kick door instead of a one-kick door." |
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//Honest people don't need laws.// |
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For some purposes, even honest people need laws. For
example, it's not self-evidently more honest to drive on one side
of the road than the other. Laws save people from having to
renegotiate things like this on a case-by-case basis. |
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The pins just need to be at different angles to each other. Picking would be more difficult. |
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Picking is helped by the lower pin dropping. Magnetism would stop this by putting weight on the top pin when the pick moves on.The set also might be more difficult to find. |
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//even honest people need laws.// |
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Fair point about driving. Okay I guess some rules are in order. |
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