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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
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.
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?
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
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.
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Death will come, and will have your eyes
-- Pavese
Actually, it's a little-known fact that all CD-ROMs do keep the CD stationary, and simply spin the rest of the universe around it. True fact. ;)
My deviantArt site
There goes my plans to turn all those free AOL disks into yoyo's to sell on ebay.
Table-ized A.I.
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
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...
Actually, it's a little-known fact that all CD-ROMs do keep the CD stationary, and simply spin the rest of the universe around it. True fact. ;)
Yeah, right. Next you're gonna tell me that CDs are flat and if you read too far you'll fall off the edge.
Some people have a way with words, and some people, um, thingy.
IWARS.
People, in general, disappoint me. Politicians even more so.
Don't forget that CDs spin backwards in Australia.
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
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.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.
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.
I'm so sorry for interrupting the rivetting and intellectual conversation on blowing the shit out of CDs.
Get back to me(in another thread, I give up here, the "nuke this thread" defense is almost as hard to counter as the chewbacca defense) when your mind learns that a straight line is not always the most productive way to reach point C from point A(ie. life, like this conversation, is full of interesting detours, don't shut them out just because it strays from the path).
Being a pseudo-intellectual is fun!
It's been a long time.