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Oh yes, destruction is good, baby! :-D
Sorry - there's something wrong with me. I enjoy destroying things. Even
intangible things like computer data. Sad, I know...
Anyway, what do we think of this baby?
http://www.computerdisposals.co.uk/hdd-destruction.htm
I don't know about you, but I wouldn't have thought this is particularly
effective. Sure, the drive is clearly rendered inoperable. But the
platters still appear to be intact, although obviously not the same
shape any more. To me, this suggests that the magnetic domains ought to
be still readable with sufficiently sophisticated equipment.
Also... I thought the platters were glass? Last time I checked, glass
doesn't bend.
And finally, how many thousand tonnes of force does it take to bend
inch-thick steel? And how do you generate those kinds of forces with
such a tiny machine?
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Le 27/07/2010 13:41, Invisible nous fit lire :
> Oh yes, destruction is good, baby! :-D
> To me, this suggests that the magnetic domains ought to
> be still readable with sufficiently sophisticated equipment.
Probably correct, expensive but correct: if you can get the orientation
of the magnetic platters, you have the data.
They are missing a journey past the curie point so far.
>
> Also... I thought the platters were glass? Last time I checked, glass
> doesn't bend.
Glass is one solution, other are aluminium (or ceramic).
The video might be with an aluminium platter.
Moreover, given the high deposit on the platters (of specific magnetic &
non-magnetic materials), even a glass platter might be seen as inside a
continuous bag of metal... we only see the external.
And in fact, glass can bend. It's just that it does not like taking too
much stress. If glass was unable to deform, the single song of a bird
would break apart all the windows of every building. And closing a glass
door with energic tamper would also break it everytime. So, glass is
elastic, a bit.
>
> And finally, how many thousand tonnes of force does it take to bend
> inch-thick steel? And how do you generate those kinds of forces with
> such a tiny machine?
Hydrolic make wonders.
Also, mechanical reduction (a small motor turning with high speed is
reduced to a very slow movement with higher force)
Given the slow move and weak excursion of the pushing cone, I would bet
for a non-reversable gear-set using a worm drive setup.
The same kind of setup which allow a small hand to put the huge tension
on a cord of a guitar.
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>> Oh yes, destruction is good, baby! :-D
>> To me, this suggests that the magnetic domains ought to
>> be still readable with sufficiently sophisticated equipment.
>
> Probably correct, expensive but correct: if you can get the orientation
> of the magnetic platters, you have the data.
> They are missing a journey past the curie point so far.
My inclination would be to just *shatter* the platters. You're going to
have one hell of a job putting those back together, and I gather the
data is spread across all the platters in parallel anyhow, so without
all the platters (aligned!) you can't make anything useful anyway.
That way, you can visibly say the data is destroyed. With heating to the
Curie point, there's always the possibility that brand X of drive has a
slightly different material with a higher Curie point, or that the
heating was uneaven, or...
(Not, of course, that any of the drives we have here contain anything to
be worth bothering with. Hell, *we* don't really care that much about
the data, so why anybody would bother trying to retrieve it...)
>> Also... I thought the platters were glass? Last time I checked, glass
>> doesn't bend.
>
> Glass is one solution, other are aluminium (or ceramic).
> The video might be with an aluminium platter.
Oh, really? All the (Maxtor and IBM) ones I've tried to destroy by hand
shattered like glass. Glass with a perculiar pewter sheen to it.
> And in fact, glass can bend.
Sure. Just only by an utterly minute amount. I'm not aware of it being
able to undergo plastic deformation.
>> And finally, how many thousand tonnes of force does it take to bend
>> inch-thick steel? And how do you generate those kinds of forces with
>> such a tiny machine?
>
> Hydrolic make wonders.
> Also, mechanical reduction (a small motor turning with high speed is
> reduced to a very slow movement with higher force)
> Given the slow move and weak excursion of the pushing cone, I would bet
> for a non-reversable gear-set using a worm drive setup.
> The same kind of setup which allow a small hand to put the huge tension
> on a cord of a guitar.
A guitar string is only under a few dozen Newtons of tension, not
hundreds of millions of Newtons.
I can see only two ways to generate such massive forces:
- With an absolutely huge electric motor, consuming many MW of power.
- With a normal-sized motor, massively geared down.
The device is tiny and runs on mains power, so it cannot draw more than
about 3 kW or so. So it's not the first option.
It also can't be the second option, because if you took any conceivable
motor and geared it down far enough, it would move at a speed comparable
to continental drift. This device clearly moves much faster than that.
I suppose maybe it uses compressed gas as a source of stored energy?
That would allow titanic forces to be generated in a small amount of
time. It might even be able to slowly repressurise itself over time when
not crushing stuff...
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> Also... I thought the platters were glass? Last time I checked, glass
> doesn't bend.
Of course glass bends, and if you have a thin bit (eg 0.3mm) it bends quite
significantly without breaking.
> And finally, how many thousand tonnes of force does it take to bend
> inch-thick steel?
For a start the steel is probably only 1mm thick, if that, and that sort of
thickness you can usually bend over your knee with your bare hands.
> And how do you generate those kinds of forces with such a tiny machine?
Mechanical advantage:
power = input force * input speed = output force * output speed.
Example is having a tiny electric motor geared down by several orders of
magnitude driving a press.
You could get a 100W motor (the sort in those hand-held food mixers), gear
it down a huge amount and you could get pretty much whatever force you
wanted (of course the higher the force, the slower it will move down).
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>> Also... I thought the platters were glass? Last time I checked, glass
>> doesn't bend.
>
> Of course glass bends, and if you have a thin bit (eg 0.3mm) it bends
> quite significantly without breaking.
I'm aware that glass can undergo a very small amount of elastic
deformation. However, I've never seen glass deform plastically before. I
didn't think it could do that.
>> And finally, how many thousand tonnes of force does it take to bend
>> inch-thick steel?
>
> For a start the steel is probably only 1mm thick, if that, and that sort
> of thickness you can usually bend over your knee with your bare hands.
Have you handled a harddrive lately? It's basically a solid brick of
steel with spaces inside it hollowed out for the platters and the motor.
Those things are, like, 80% solid metal! (Indeed, in a world where
seemingly everything is cheap and slimsy, there's something satisfyingly
rugged about a HD...)
>> And how do you generate those kinds of forces with such a tiny machine?
>
> Mechanical advantage.
>
> You could get a 100W motor (the sort in those hand-held food mixers),
> gear it down a huge amount and you could get pretty much whatever force
> you wanted (of course the higher the force, the slower it will move down).
That's just it. If you take any feasible size motor and gear it down
sufficiently to generate the collossal forces required, the thing would
move so slowly it would make continental drift look fast. Yet this
machine doesn't appear to do that...
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On 27/07/2010 2:56 PM, Invisible wrote:
> the thing would move so slowly it would make continental drift look fast.
There is something wrong with your thinking. Instead of coming up with
work. Unless you think that the video is a fake it must be possible.
--
Best Regards,
Stephen
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> However, I've never seen glass deform plastically before. I didn't think
> it could do that.
No, it tends to fail before it deforms plastically. Doesn't mean glass
can't bend or exist in a bent state though (you just need some force to hold
it there).
> Have you handled a harddrive lately? It's basically a solid brick of steel
> with spaces inside it hollowed out for the platters and the motor.
Yes, and also about 10-15mm thick, so I fail to see how the case around the
platters is an inch thick.
> That's just it. If you take any feasible size motor and gear it down
> sufficiently to generate the collossal forces required, the thing would
> move so slowly it would make continental drift look fast. Yet this machine
> doesn't appear to do that...
You only need to crush a distance of about 10 mm, and I assume you want that
done in a few seconds, so I make that about 2mm/s, and given a 100W motor
that gives 50 kN. I haven't tried it, but it sounds enough to do some
serious damage to the drive...
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