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Spinning Disc of Death

R

redbone75

Member
In all my years of using computers, I have never before experienced a situation like this:

I was just getting ready for my morning run and started looking through some old disc backups and came across some music that I forgot I had. Cool, really wanted to get some of these on my mp3 player and decided to do just that. Put the cd into my dvd drive (NEC 3520a, bty) and heard the normal spinup-- no prob. Then I noticed that the spinning didn't stop, but actually got a little louder. Suddenly, I heard this pop come from my drive. I looked down and noticed that the drive tray door was bent outwards. Bent outwards?!?! Powered my system down, which Windows had completely locked up anyway, and tried to manually eject the drive tray. No go. Removed the drive from the tower and I could hear the pieces of the broken cd. Pieces! One large piece about 1/4 the disc and the rest are only about half an inch in size. I wonder how fast that disc was spinning!

Either the disc decided it wasn't going to be violated or my drive thought the cd tasted bad, I don't know. But, what I do know is that I have to buy a new dvd burner because this puppy is not reading anything put in it. Totally sucks, especially because it seems that I can't hold on to a dvd burner for more than about a year. This is a replacement for my Plextor 708a that died 13 months after purchasing it in January '04, and I bought this one in March last year. Would have bought another Plextor but decided on this one since it was recommended by Anandtech in a price guide. In all a bit disappointed with it since my Plextor wrote faster at 8x than the NEC does at 8x, and at 16x the NEC wrote a full dvd in about 5 1/2 minutes, only a minute and a half faster than the Plextor's 8x write speed. Oh, well, getting a bit off my own topic here. But seriously, have any of you heard of something like this happening? The tower was completely stationary, of course, so unless the disc was warped, which it didn't appear to be, I don't know how this could have happened.
 
Cool. Now I can rest easy. I've heard of this happening before but never experienced it firsthand, so I thought it was a rare event. I'm glad I didn't have a slot loading model <cringes at thought of cd imbedded in leg>
 
Yeah, I've heard that's why you can't generally buy really fast speed drives. You dont see anything faster than 48x these days.

RoD
 
Yeah, mythbusters did a thing on the CD rom "O doom" once, and those things would be dangerous if not for the fact that they are enclosed. *grin*
 
Here's some quickie napkin math since this question got me thinking.

1x CDROM = 500 rpm

CDROM outer diameter = ~12 cm
CDROM inner diameter = ~4 cm

The "48x" CDROM speed cited compares the data transfer speed of the inner part of the CD at minimum speed, to the data transfer speed of the CD's outer edge at maximum speed. Since the outer edge is 3x the inner area in circumference, to get 48x data transfer we really only need to spin the CD 48/3 = 16 times as fast. So:

"48x" CDROM = (500 x 16) = 8,000 rpm

The mechanical stresses placed on a CDROM at 8,000 rpm are quite often enough to make it shatter. This is especially true if there are any imbalances introduced into the CD during the manufacturing process, or if there are tiny cracks in the inner mounting ring of the CD (which sometimes happens if you snap it in and out of a jewel box enough times). Now if the CD shatters at 8,000 rpm... the outer edge is moving at (12pi) x 8000 = ~ 300,000 cm/minute or about 50 m/s, before allowances for any energy lost in the shattering of the CD as well as to atmospheric drag. Anyway sharp objects moving at 50m/s are not enough to kill you but they can certainly blind you.

For experimental validation, mount a CD at the end of a Dremel tool and spin it. Dremels do about 20,000 rpm so it should be more than enough to make a CD fly apart before too long :evil: Make sure to wear goggles!
 
Yes, a lot of drives that are rated at 48x or higher usually come limited to 40x or lower and you have to manually crank them up. Pressed media should not be spun at high speeds as the OP's story is not uncommon. Only use the high speeds on media that is rated for it - even then it is wise to crank the speed back as the quality of your burn (or read/play) will be much better.

.bh.
 
One time in my computer class sophomore year of high school some kid was using the cdrom and all of a sudden we heard this big BAM! and then the drive sounded horrible, cause it kept trying to spin the pieces and it was moving all the broken pieces around in the drive.. I was glad when the power was torn out of the back of the case cause it was so loud.
 
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