Slashdot Mirror
When Spun Really Fast, CDs Explode
Anonymous Coward writes: "Ever wonder why cd-rom/cd-rw drives are not getting any faster? Wonder why they heat up? This page has a rather amusing experiment where they put various CD's into something that can spin up to 30,000RPM and found that most cd's explode at just around 28,000RPM. Oh and they seem to like using Corel CD-ROM discs for their experiment." Update: Yep, it's a dupe...
I prefer to just microwave mine..
no soup for you
Don't those 52X ones have multiple read heads so they don't actually have to spin that fast?
also you can always just put more data on the disk. I mean maybe you could never read a 100GB disk faster than 52X, but thats still like 100GB of data read in a minute or two
They should at least have chosen AOL CDs to destroy. Sheesh.
Al.
REPOst repost repost repost
A lot of bands might consider exploding CDs a feature. :-)
This is my post. There are many others like it. If you don't like what you read here, go try one of the others.
just a post a link to it on slashdot and BOOM, there goes your hard drive...
Who is this Karma guy and why is he bad ??
I hope the server doesn't explode as well ...
This story (with the same URL) was posted here. I know duplicate-URL checking wouldn't help everything, but it could at least catch stuff like this...
PenguiNet: the (shareware) Windows SSH client
I can see it now, the RIAA manufacturing discs that experience structural failure when you spin them faster than 1X to rip them....
:-)
oh boy.
Wonder what happens if you spin a floppy at 30,000 rpm?
I want to see more of this kind of story!
I want to see what else can explode in my box. I want to see what happens (with big color pictures) to to a hard drive at 20000 atmospheres of pressure. I want to see ASUS vs ABit mobo's head to head for resisting g-forces. I want to see what happens when you force 100,000 volts through a cat-5 cable.
Isn't this what the internet is all about, pictures of stuff exploding, videos of people endangering their lives for my tittlation while discovering what happens if you fill a case with gasoline and run it as a server. Get cracking people.
Oh great. Now CD players will be banned from planes.
Table-ized A.I.
Is it so hard to post the link? Or is HTML too difficult for you?
It's slashdotted; I've at least got the text mirrored; images added as I get them.
e xp lode
http://wuarchive.wustl.edu/users/tom/mirrors/cd
Find yourself an old 40x (or so) drive that you no longer need and get ready for some fun (tested on tray load drives only so far).
:)
:)
Grab an AOL or old magazine CD and make a few small cracks (so they don't go into the data area) about 1cm long on the inner edge of the CD (aka the hole in the middle of the CD). Then put it in your high speed CD reader and start reading data - with luck after a minute or so (maybe longer) you will hear a loud BANG and the CD will no longer be spinning
Sometimes you tray will eject still but more often than not you will have to take the drive out and shake the bits out. When you are shaking you may find other bits like the small CD laser lens and small pieces of metal - in which case you drive is probably fux0red now....
I did this to my work PC drives.... old Diamond Data and Fujitsu drives that use to piff me off for various reasons
You look around hardware review sites you will come across readers stories of similar experiences where the CD structural integrity has failed and tried to spread itself over the insides of the PC case.
- HeXa
The article talks about constant linear velocity (used in the original audio standard) and constant angular velocity drives. It comments how manufacturers like to have CAV drives to quote impressive speeds compared to the CD (audio) standard, but doesn't mention a much more important reason for using CAV: if you used CLV you'd need to wait for a long time (probably seconds) for the spin rate to change and stabalize whenever you seeked from one part of the disk to another.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
Contrary to popular belief, plastic doesn't last forever.
:)
Since CD is made up of two layers of clear plastic, sandwitching a thin wafer of metal media inside, the more the CD is aged, the weaker the plastics of the CD become.
And so, the maximum spinning speed for a CD depends on how old the CD is.
I do have some pretty old CDs from the early 80's, and I will NOT put them in my 52X CDROM drive. Unless of course, I want to scrap bits and pieces out of my machine.
Aw, fuck it. Let's go bowling. - The Big Lebowski
Would it be possible to leave the CD stationary, and spin the laser instead?
"I'm givin' the CD-ROM drive all it ken handle, Captain, anymore and the discs will explode!"
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."
I'm in the process of converting a WGP Autococker into a CD/DVD Launcher - specially flattened barrel, tightened on one side to impart a spin - to launch Compact Disks with a burst of CO2. Although the CD's needed to be loaded by hand, one at a time (up until recently), I can reliably attain ~550 ft/s. This is enough to cleave thick pieces of styrofoam/cardboard or aluminum cans in half... or embed itself into soft wood like Eucalyptus trees. Against harder targets, such as rocks, the rounds simply undergo fragmentation and splinter into tiny plastic chunks. I don't know the effects against animal matter yet, because the contraption is notoriously inaccurate and squirrels are annoyingly fast. :)
At higher velocities (~700 ft/s) the rounds begin to fragment in the "barrel". I'm currently examining other alternatives to increase the velocity, but I guess now I have to take spin to account.
Other notes: I've put together a rudimentary feeder/hopper that now lets me use my CD Launcher in a semiautomatic fashion (and wastes more CO2 per shot)
Solomon
PS: I'm slapping together a solenoid-actuated electric trigger frame (similar to a Sandridge) to convert my paintball^H^H^H^H^H^H^H^H^H CD gun to a fully automatic weapon. I don't know if it will work... yet. (I have given thought to converting an Angel, but I'm not willing to futz with $1300 gun, and I've been doing my own custom internals on 'Cockers for years now.)
I estimate a potential ROF of ~13 CDs/second. (maybe *now* I'll be able to hit that pesky squirrel) My anticipation is that it still won't do any damage to brick walls, bronze statues, and masonry of quality craftsmanship, but will absolutely *shred* old wooden fences, thrown-out sofas, and squirrels.
BTW, I once thought of calling it my Assault Ordnance Launcher, or AOL for short... the idea being that people would soon become afraid of my AOL CDs...
"Twice half-assed makes an ass whole." --Solomon K. Chang
OK. The staff can't be perfect, but this is not even close to being all that unique. I remember this story as well.
I suggest the department headings be changed from frivolous titles to useful ones, to help with categorisation. I'd also like to see duplication URLs recorded, as Sircus suggests.
Someone here noted that Slashdot has an option to show all sections. Perhaps editors should have this as a mandatory condition on their own logged-in sessions.
========================================
Death will come, and will have your eyes
-- Pavese
is that tremedous amount of energy is stored in the disc. Supposed that the disc is spinned very fast but before the break point, and someone stupid enough to stop the spinning(like open the cd tray while the light is on, we all do that don't we), the loosing disc will break out of the case and kill a couple of people nearby.
There goes my plans to turn all those free AOL disks into yoyo's to sell on ebay.
Table-ized A.I.
It is from the Department of Redundancy Department. I know I have seen this before too.
Some people seem to be missing the point on CD's DVD's and other forms of optical storage. Speed is nice... but cheap is better If you need insane speed buy a hard drive. If you want compact and rewritable use flash memory... I got several negative comments about not liking new disc sizes in optical storage a couple days ago...
will be one of two things I think:
1. The CD will be spun at 64x or so clockwise. Under that will be a second counter-rotating plane that will contain the laser. With the platters rotating in opposite directions you can break the 30K RPM physical limitations of the media. You can build the mechanism strong enough to do 300x normal CD speed I'd guess. 300 * 64 = 6,000x or ( 2.5GB/s). I wouldn't be surprised to start seeing such a mechanism in hard drives either. The disks i
2. What I think will truely be the big breakthrough will be to not spin the disk or reader mechanism at all. Instead, the drive will use a scanner like method to read the entire CD in to a 700MB buffer in a few seconds. The disk will then sit idle while all requests are served from the buffer. I see this used in a slot loading scheme, so as the disk is drawn in it is read.
The nifty thing about this would be that you could create a CD image in the buffer, change the bugger copy just like a normal disk drive, then eject the physical master and burn the buffer to a new CDR(/CDRW disk.
Article X: The powers not delegated... by the Constitution...are reserved...to the people
I don't know about that...
I do know that I had some fun with an old 5 1/4" Full Height HDD and a 3-phase grinder once.
Did you know that you can spin hard drives like that up fast enough (mostly safely) to actually make the centripetal force cause the drive to stand up on a corner for a bit! FUN FUN FUN! More fun than jumping off a moving bike to see how far it will go before it falls over (or hits something). Even more fun than trying to roll a quarter completely down the college hallway during late hours!
(and no, even with the stress the grinder put on the platters and the high speeds nothing "exploded"... but someone did mention to me I should have worn protective gear anyways.)
If you could be told what you can see or read, then it follows that you could be told what to say or think - BoC
Anyone with a passing interest in radio controlled airplanes already knows this fact:
Plastic propellers disintegrate at high rpm.
So they use wooden ones. The document (the cached version, sans photos) did not go into great detail about the nature of the material failures, which they claim will be investigated with SEMs, but it would be interesting to use their same setup with same-size components made of other materials. A wooden CD-sized disc, an aluminum one, etc.
Not that CDs should be made of wood, but certainly plastic at high rpms is a compromise between cost and durability.
At what angular velocity would a child (~30kg) explod on a merry-go-round? What would happen if they were to have a CD in their pocket?
Welcome to the land of the free...pay toll ahead...no photography...please open your bag...
Good idea, except they'd probably break in portable players with skip protection, as those spin the discs faster than 1x.
Got friends?
The speed of sound is about 1130 (depends on temp) feet/second. a 5.25-inch disc's outer edge would be spinning at around 1282 feet/second - in excess of the speed of sound. I'm not well versed of the physics of the equation, but it seems that the disc's outer edge, having broken the speed of sound, would be the recipient of some extreme air pressure and turbulence that would cause the edges to break, and the uneven weight distribution would do the rest.
Of course, I'm just taking a stab - could be wrong.
That what was all this school was for... to teach us how to solve our own problems. -- janeowit
Suffice it to say that this is indeed a repeat. An amusing one, true.
IWARS.
People, in general, disappoint me. Politicians even more so.
Plextor drives can be 'underclocked' with software switches fairly trivially, using free tools. They also let you do some fanciness like control spin-down times, and how the drive responds to errors.
OTOH, the fastest drive Plextor makes operates at 40x CAV. And I've fed many, many messed up (cracked, deeply scratched, off-balance) CDs into my 32x Plextor, without ever having one disintegrate, even when they're spinning at high speed for 12 hours or more.
So, personally, I'm not too worried about the safety aspects. But if you want to slow down a CD-ROM for whatever reason, Plextor is a very sure route to follow.
Kid-proof tablet..
There'd be no need to spin anything if you took CD drives to the ultimate extreme. Just integrate 700 million microscopic lasers onto a 4-inch wafer. Hold it next to the CD and, Bam! Read the entire disk in 10ns.
Let's see-- that's about a 420,000,000,000-X drive. That's the kind of product spec that makes for a sure-fire winner in the marketplace. Might need to consider upgrading to a somewhat faster IDE interface version, though...
CD transfers speeds are lower than hard drive transfer speeds because hard drives have multiple platters and higher data density.
A 7200RPM hard drive today may be able to sustain 40MB/s transfer rate, but that comes from at least four read heads. Each head is only transfering about 10MB/s. That roughly equates to 60X in a CD burner.
So a single read head of a hard disk at 7200 RPM is roughly equivilent to CDROM at 22,000RPM(avg).
And that shows us that the HD data density is much greater than that of a CD. The reason: CDs are a portable media. The have to remain compatible for long periods of time. You can't just arbitrarily shrink the size of a bit or change the encoding scheme. If this happened you'd need to purchase new CD players and CDRW drives every six months to keep up with technology. HDs are non-portable. The media is treated as a black box. You never need anyone to be able to read the media, just send the proper commands to the interface to the black box, so you can do whatever you like to the medium's format.
Article X: The powers not delegated... by the Constitution...are reserved...to the people
I know this is a Troll, and probably has already been mentioned. But just for morbit curiosity's sake, I entered the word CDROM into the search field on slashdot, clicked submit. And what do you know! The duplicate article was #4. FOUR!
This took me all of 5 seconds to check. This
wasn't something about Microsoft that would be buried 10 pages back, no. This shows up at the upper half of the upper quarter of the list of responses to a simple 10 second (I wonder if we did this before) check.
I know dupes are going to happen from time to time. With several editors, its impossible for all of them to know off the top of their heads if the article has been posted before. Even if it were only one person, I still wouldn't hold it against them that much. But some modicum of effort should be taken to at least avoid looking like a complete moron. This means, make sure its not still on the front page somewhere (this includes the older stuff links), make sure you can't find it in the search list with one or two
of the common topics of the article, and perhaps,
if possible, do a quick check on the URL to see if its been mentioned before.
-Restil
Play with my webcams and lights here
Dremels can spin much faster than 30,000rpm. Those motors have a field winding and an armature winding. If you decrease the field current, it causes the armature current to go through the roof. This is called "field weakening" and is a common method to get motors to spin faster. The motor's speed can be expressed as a ratio of armature/field current. The motor's speed is that ratio.
AC motors are tricky to do that with, but one sure way to overclock a dremel motor is by "overclocking" one of those 120VAC inverters. Look for an opamp that generates the clock frequency and the resistor for that RC circuit can be replaced with a potentiometer. You can vary the frequency from 0 to about 400Hz. Higher the frequency, the higher AC motors will sync. Don't go to high on the frequency or the inverter's mosfets will exceed their slew rate. That means most of the energy they are trying to switch will be disapated inside themselves, because they can only switch between the voltage rails so fast. Another resistor on the opamps will adjust the voltage for charging the storage capacitor. This one will have the greatest effect. You can get most inverters to pump out over 200 volts. Use an oscilloscope to track down the inverter's signal generator.
I found a non-overclocked dremel will easily cause the cd's outer tracks to skew. Extreme vibration will be the result as the cd warps quickly. Speed will drop quickly due to this imbalance. Solution: turn up the power!
The "ring" could work much like a phone cord detangler - bars at extend each to a different ring. The other problems you have here:
Synchronization: Getting the laser at one spot on a CD is a complex process (so much so that a buffer underrun can cause a misalignment in a burnt CD, making coasters). If you spin the CD and the laser at different variable speeds, you would need some great hardware calculating that would be able to put the two speeds to gather as they vary.
Communication: Getting power is pretty easy, but what about returning data? You could use the same spinning wire-on-ring system, but I think it would limit the communications bandwidth.
I think a better system would be to have 2+ read heads on a CD-ROM. Two or four read heads could more quickly access data if they were fully independant. Drive access time could be halved, as could seek time. Two heads could "stripe" data, allowing the transfers to be even faster.
Well, I'll stop.
That what was all this school was for... to teach us how to solve our own problems. -- janeowit
A 64x CAV CD-ROM drive will spin at a maximum of 12,800 RPM, according to my math, but drives don't seem to exist at that speed just yet. More common 56x drives spin at 11,200 RPM.
If things are consistantly and violently exploding at a little over twice that speed, would it not make sense that there is a very real safety issue in making things faster than this?
One might theorize that off-balance discs, cracked/scored/otherwise-damaged media, and just plain bad luck might cause things to go dangerously amiss even at current speeds.
Current high-end SCSI hard drives spin at 15,000RPM, but do so using extremely well-balanced, carefully-produced, expensive solid aluminum platters and motors. And, besides, they're also encased in heavy metal boxes, and don't have a soft plastic face through which to fire shrapnel into the chest of the user.
Consider that a CD-ROM has a much larger diameter than a typical hard disk platter, and is thus exposed to far greater centrifugal force and linear velocity. Consider also that a CD-ROM drive only costs a few dollars to make, and that CDs are down to a couple of cents each in large volume.
Given this information and that contained in the article, I doubt it would take much effort to make a CD explode in a current 56x drive, thus presenting a very real bottleneck, indeed.
Kid-proof tablet..
- A giant fan aimed at a heat sink attached to the spindle that grips the CD
- Pressurized CD-ROM drives
- A sticker on the "5x-the-speed-of-sound" drive stating that by using this CD-ROM drive, you agree that the speed of sound is one-tenth the speed the rest of the world claims.
One of the above would be appended to what we know today as a 24x CD-ROM drive.THE POINT:
SO... TO MAKE OUR SKIES SAFE: only 3 at a time, naked and with hand and feet chained fast to your seat; nothing else in tow. that would about do it.
Hmm... the passengers naked & chained to their seats. Welcome to Bondage Air where the Second Class is REALLY Second Class and the First Class gets deal out discipline to those naughty naughty Second Class riders.
I see a market for this somehow.
"Face it, a nation that maintains a 72% approval rating on George W. Bush is a nation with a very loose grip on reality.
At least it didn't make the stupid suggestion that CD-ROM drives don't seem to be getting faster because they're nearing the speed at which CD's might explode from G-forces.
The real reason for the limited speeds that can be reached with CD-ROM drives is the vibrations in the CD resulting from motion in that speeds. If the CD moves too much, the laster can't read it properly. Hence, the reason why caddy drives used to be popular - the caddy helped keep the CD still, thus allowing the drive to spin it faster.
If you want a faster CD-ROM drive, you'll have to do what they did in this experiment - tighten the CD down so that it is always perfectly coplanar with the plane of rotation.
Zen Research has developed a technology that reads the disk using 7 beams in parallel, achieving high throughput without spinning the disk at ridiculous speeds.
It has been licensed by several companies including Kenwood that used it to produce an amazing 72x drive.
Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.
This story was ran a few week back, and was proved a dupe back then because of their is no such thing as a kelvar enforced cd.
When you get some READING COMPREHENSION SKILLS, get back to us.
They wrapped some KEVLAR WIRE around the CD to reinforce it. They could have easily made it COPPER REINFORCED by wrapping copper wire around the CD too. Goodness sakes, I hate WILLFULLY STUPID PEOPLE.
"Face it, a nation that maintains a 72% approval rating on George W. Bush is a nation with a very loose grip on reality.
The second, and not so obvious solution is to spin the player in the opposite direction of the cd. Then both can rotate at their maximum angular speed, and the effective angular speed will be the sum of the CD-speed and the player speed. I'm not sure how fast you can spin a cd-player before moving the heads precisely will become a problem, but if you throw enough money at it, I'm sure it's probably close to the speed you can spin a CD at.
On the other hand, I'm relatively happy with my 40x burner. 2-3 minutes for burning a full CD is about as tolerable as floppies used to be. If I want something more from CDs now, it must be safety (never loose data), storage capacity, and being able to use them as a real read-write medium, not something that needs to be "blanked".
The site is slashdotted, so here's a link to the google cachie.
---
"The chances of a demonic possession spreading are remote -- relax."
Of course, I'm just taking a stab - could be wrong.
Actually, because of centrifugal force and gyroscopic forces a spinning disk is inherently stable, and resistant to any turbulence or wobble. Likewise, the aerodynamic crossection of a hardrive platter is pretty negligle. Flywheels often spin at several times the speed of sound, often well over 60,000 rpm using disks measured in feet. Most operate in a vacuum condition, where there is nothing to turbulate. If a flywheel breaks vacuum suddenly the efffects might be catastrophic, The energy released during the failure of a 1 kW-h flywheel is enough to lift a mid-size car 100 feet into the air
Could Jesus microwave a burrito so hot, that he himeself could not eat it? HS
I believe there was a turntable in the late eighties that did that. The record stayed still while the tonearm tracked linearly from the out side in and rotated the record. Couldn't find anything on google about it though. I think it might have been a Bang & Olufsen.
Or 7, like kenwood did three years ago. Though, I think that they are using only one laser and beam splitter and mirrors and stuff instead of multiple lasers.
_________________________
Spelling and grammar mistakes left as an exercise for the reader.
All you would need to do is have a rotating mirror put on the axis of the spindle, and bounce the laser off the mirror. Only problem would be proper laser focus at the edges of the CDs.
You can probably spin a mirror much faster than a CD disc or the laser itself...:-)
I never had to buy a 1.44M floppy for years... I just asked for AOL trial floppies a couple of times, and every month they'd sent me loads of free disks.
It really sucked when I started getting about 3 CDs a month from them, though.
I know part of the reason for using small DVDs was anti-piracy (though dvd-rs in that form factor should be available before long, if not already...), but perhaps some stuff in the article relates to the choice of such a small disc. With the small disc, there is a much more consistant speed with a constant rotation rate from innermost to outermost track. And that speed could be close to normal DVDs at the outermost tracks, since it could be spun faster with lower risk and noise... Just an offtopic thought...
XML is like violence. If it doesn't solve the problem, use more.
Also don't allow belts, luggage straps, shoestrings, or anything else that could be used as a garrote. Laptops and hardsided briefcases must be banned, you could bash someone's head in. And take those crutches away from that cripple, he could do real damage swinging that around - or maybe even conceal a weapon inside. (The last time I flew, the stewardess actually did seat a guy on crutches, then took the crutches out of a passenger cabin - I'm not sure if that was security or just because that commuter plane was so small.)
Or maybe just handcuff everyone stronger than a 1 year old.
Or, really radical idea - encourage citizens to actually defend themselves, instead of acting like subjects like a dictatorship and doing whatever the thugs want until the gov't thugs show up...
We've had two CDs go in the last 6 months in my office, both in 50x drives. One was a CDR, the other was an original photoshop CD. In both cases bits flew out of the front of the drive, and they didn't half make a noise! One of the drives work afterwards, despite having bits of plastic knocked off by the exploding disc.
Dangerous if you ask me - if you have a tower case, make sure the CD drive isn't at eye level!
I hope you are joking about airlines banning nail clippers. Have they gone THAT FAR?
I've known a few women who have nails more dangerous than the clippers. Will they make them wear gloves and a gag?
Actually, I don't mind getting AOL CD's when they come in a nice DVD style case. I just tear all the crap off of it and, boom a case for my VCD's.
--Won't that be grand? Computers and the programs will start thinking and the people will stop. - Dr. Walter Gibbs
A fun experiment is to put a polished, hardened steel rod through the spindle hole, then hit it with a jet of compressed air. If you get the bearing effect just right the CD will spin up to a 10-20krpm and will occasionally disintegrate on the spindle. Mostly though if you let it slip off the spindle it'll hit the ground, stand due to gyroscope effect while the edge melts against the ground enough to get traction, then take off across the room and explode on impact with the opposite wall.
You can also make an air bearing with an orange by cupping your hand just right and blowing compressed air between your hand and the orange. Oranges explode good.
In other news, CDs shatter under high impact. They have a tendancy to melt when exposed to very high temperatures. Oh, and don't try to put them under too much tension or shear either.
Hey, Einstein! What doesn't break when spun fast enough? This is news?!?!
This story sounds like bunk, because of two things. First, if anybody can provide any proof at all of Winchester drives with six foot platters I'd like to see it, since the largest drive I've heard of or worked with is 18 inches across. Second, "forcibly clamped down"? How, exactly? These old drives had brakes on the spindle (the operator would stop them and lift them out with a handle on occasion, which led to another urban legend about a guy who opened the case, and the brake interlock failed, and he put a clamp down on a spinning platter stack and got his arm twisted off), but those brakes were nowhere near strong enough to stop the platters cold, and these were only a foot and a half across.
The truth of this, however, is strange in and of itself. It was indeed possible to drop a platter stack in crooked, such that when you removed the clamp, closed the lid and spun them up the drive housing would start banging around like an out-of-balance washing machine. It was also possible to design seek programs for the step motor (the one that moves the head across the platter) such that you could cause the drive housing to move. With a properly designed progam and a near-felonious disregard for the equipment, you could move a drive housing several feet. I was privy to a contest some time ago where several programmers competed to try to get the drive housing to move to certain places in the lab (using an old, blown-out platter pack, of course, since we really didn't want to be wiping out a good one).
Virg
Well, I suppose that you COULD spin a hard drive platter at high enough speed that it would fail catastrophically, but it's MUCH more likely with the 3.5 and 2.5 inch drives than the old 5.25 inch drives.
...
The platters in 5.25 inch drives were aluminum, which is relatively soft and fairly ductile. I suspect that before the centrifugal force got high enough to cause the platter to fly apart, the spindle hole would stretch enough that the motor would no longer drive the platter
The high strength materials used in the smaller drives would, IMHO, be MUCH more likey to hold together long enough to "explode."
Just my US$0.02
utter rubbish
We had one poor lady in our office who was trying to
install a feature of MS Office from her CD-ROM. She stuck the thing in and after about 5 seconds there was a loud bang from the computer. She nearly hit the ceiling when she jumped.
After checking signs of smoke and what not, we opened the CD tray and there was nothing but a shards. It had completely disintegrated into pieces no more than a couple cenitmeters long.
Of course the drive was completely hosed after that. It just made a jingling noise with all the shards in the unit.
Yet another fine M$ product - exploding CD's.
The old-style Aluminum-shell SCBA air tanks (used as an oxygen supply for firefighters) are only about 1mm thick...and they routinely carry air at a pressure of 22,000 psi.
Those plastic fragments were able to crack open 1mm thick aluminum shielding! That means that the pressure those fragments applied was well in excess of 22,000 psi! Yikes!
What's this Submit thingy do?
It's a well known fact that the universe revolves around ME.
It is by the juice of the coffee bean that thoughts acquire speed, the teeth acquire stains. The stains become a warning
Actually portable cd players and md players is banned from some airline companys.
That is because they are afraid a terrorist will play Yoko Ono, not because of spinning breakage.
Table-ized A.I.
"... then take off across the room and explode on impact with the opposite wall. "
Or your head!!!..
[alk]
I hope you are joking about airlines banning nail clippers. Have they gone THAT FAR?
Lord, wher have you been? :-) My wife had her clippers confiscated, broken, and then handed back to her by the security people on her trip to OK. Unreal. I'm surprised they let her wear her diamond engagement ring; they'll leave a nasty tear in your face if you get hit with it.
I'm the poster that submitted the orginal link.
/.'d. I wish there was some way to know if a site could handle the traffic, and then submit a google cache instead.
I felt bad the first time the site got
Maybe before submitting a story, people should send an email letting the site know their page might be getting linked from slashdot?
> ]. I know duplicate-URL checking wouldn't help everything
I agree, even having a basic script which checked for duplicate urls would be welcome. Heck, make it per user configurabe.
i.e.
[x] Don't show duplicate stories
Cheers
Don't burners always do CLV when writing? Are the 48x burners multilaser or someting? 48x would be ~25K RPM (about as fast as a 125x CAV reader, if my math is correct), which seems close to/over the limit.
Are the media with higher speed advertised actually sturdier?
--
Benjamin Coates
Secondly, it wouldn't apply on the grounds that a cd shooting gun isn't a "firearm" the projectile is propelled without gunpowder, so there isn't as much regulation governing it
Every state has it's own weapons laws. Note they are never called firearms laws, they are "weapon" laws, and are usually written ambiguiously enough to include most types of projectile weapons. Of course, it doesn't matter what the actual device is, if you use it to seriously injure or kill someone, it's considered a deadly weapon. A baseball bat is perfectly legal to own. You can even keep it in your back seat without much hassles from police. Yet as soon as you jump out of your car and pull that bat, it becomes a deadly weapon and you are much worse of for having it.
The CD gun is no different. If he kills the squirrel, he's can be charged with weapons violations (as well as cruelty to animals for not killing them with an approved method of hunting, maybe also hit with hunting out of season and poaching fines). Just as if he'd killed the squirrel by knocking it out of the tree with a paint pellet originally designed for the gun. As long as he doesn't use it illegally or recklessly, he should be ok, but no telling where a cop draws the line when it comes to "recklessly" and arrests him for endangerment.
-- If god wanted me to have a sig, he'd have given me a sense of humor.
I'm not ducking out, but this thread has made a 90 degree turn from the topic only four messages back.
Could someone please mod down this and the last three messages in this thread? It's really just pointless bickering between two people who can't bear not to have the last word.
What's this Submit thingy do?
People have mentioned that some drives use multiple read pickups rather than high rotational speed, but I've been wondering why we have to spin the media at all. Wouldn't it be possible to read the disk by using some spinning mirrors to rotate the optical path around the CD instead? Perhaps it's a space issue, or a need to keep the pickup close to the CD, but it just strikes me that the technology is limiting itself by following designs based on older technology (like 78rpm records!)
I'm an American. I love this country and the freedoms that we used to have.
"Current high-end SCSI hard drives spin at 15,000RPM, but do so using extremely well-balanced, carefully-produced, expensive solid aluminum platters and motors. And, besides, they're also encased in heavy metal boxes, and don't have a soft plastic face through which to fire shrapnel into the chest of the user."
;)
You've convinced me... I'm switching to SCSI.
Communication: Getting power is pretty easy, but what about returning data? You could use the same spinning wire-on-ring system, but I think it would limit the communications bandwidth.
Unless you've got a uart or something similar on the spinning arm, the laser (or rather the component that receives the laser light) is only sending a bit of information at a time anyway. Look at the ribbon that connects a laser assembly to the main board on any cd player today. Only 4 traces. Power, Power Ground, Signal, and Signal Ground. 4 wire rings is done with phone cords today, so why can't it be done with this?
That said, I think a spinning mirror (e.g. supermarket scanners) would be a lot simpler and still get the job done.
The problem with strengthening the discs is you lose backward compatibility. What if the CD-ROM drives start assuming the discs are stronger and they increase their spin speeds? Somebody somwhere is going to ignore all that confusing computer terminology and put in their old CD, spin it till it explodes, and then sue the CD-ROM drive manufacturer. Unless the drives can somehow determine that the CD is not the new "strong" format, manufacturers would not want this kind of liability.
I really hate signatures, but go to my website.
hrm.
;)
That's why I like my 32x Plextor. It's nearly silent, and has a few very neat programmable options:
The disc can be automagically spun down to a slower speed if excessive vibration is detected. This keeps it quiet, but should also help with CDs that are ready to burst into shrapnel.
The drive can slow down for read errors, or just zip along as fast as possible as often as possible. (this latter option might be good for video, where it's more important that data arrive on time than it is for it to be accurate)
The drive can be told -never- to spin faster than a given speed. (great for ripping audio CDs)
The drive can be instructed to start transferring data before the disc reaches whatever speed is considered ideal (based on the above parameters).
That last option, combined with programmable idle spin-down time, can eliminate spin-up delays in almost all cases.
If I wanted to, I could have my drive running at 1x, -all day-, waiting for me to access it. And when I finally do want some data from it, it'll start transferring immediately, and then start spinning up to some quick-but-sane speed.
I've gotten thousands of hours (not power-on hours, but real-live usage) out of this thing in the 3 or 4 years I've owned it, and it hasn't missed a beat yet.
And support? It doesn't have a flashable firmware, but Plextor sent me the latest ROM (as in, a tangible IC) free-of-charge, just for asking. I didn't need it, but I'd been restoring damaged audio CDs, and it did help a bit with that.
Otherwise, I've never had to talk to Plextor support for anything I've owned or spec'd from them.
Not a very good business model, though - I'll probably never need to replace it.
Kid-proof tablet..
Why not use a grocery-style scanner to speed up access times? You can cover the whole disk with a spinning mirror, and keep the Rpms down at a resonable level.