How fast does a CD drive go ?

P

Phil Allison

Guest
Hi all,


Pursuant to the "Mythbusters" show - how fast DOES a so called " 52 times
" drive actually go ??

The linear track speed of a music CD is from 1.2 to 1.4 m/S - which on
the inner diameter of 50mm gives an rpm range of 458 to 534 rpm.
Multiplying those numbers by 52 gives an rpm range of 23,816 to 27,807
!!


Where is the catch ?




................. Phil
 
"Phil Allison" <philallison@tpg.com.au> wrote


Pursuant to the "Mythbusters" show - how fast DOES a so called " 52 times
" drive actually go ??

The linear track speed of a music CD is from 1.2 to 1.4 m/S - which on
the inner diameter of 50mm gives an rpm range of 458 to 534 rpm.
Multiplying those numbers by 52 gives an rpm range of 23,816 to 27,807
!!


Where is the catch ?


*** Probably in the "by 52" Area. By 52 of what?

Brian Goldsmith




................. Phil
 
Phil Allison wrote:

Hi all,


Pursuant to the "Mythbusters" show - how fast DOES a so called " 52
times
" drive actually go ??

The linear track speed of a music CD is from 1.2 to 1.4 m/S - which on
the inner diameter of 50mm gives an rpm range of 458 to 534 rpm.
Click to expand...
I would have thought about half that just by visual observation, but you
could be right.

Multiplying those numbers by 52 gives an rpm range of 23,816 to
27,807 !!
Could be about the right magnitude.
Click to expand...

I regularly write at 25x so a whole CD takes 2 minutes.
Thats switching on/off the laser at
- over 40 megabits/sec.
- 21 nanoseconds/bit

gtoomey
 
52x of Single speed .. which, for data, is 300k/sec ..

I don't think audio is the best measure, because it is always played at 1x
... reading it, as in ripping audio, at higher speeds no longer needs to
maintain a linear speed throughout the disc ..

Google up on CAV and CLV.. 2 different methods of disc speed control ..



"Brian Goldsmith" <brian.goldsmith@nospam.echo1.com.au> wrote in message
news:4KFLd.143561$K7.112149@news-server.bigpond.net.au...
"Phil Allison" <philallison@tpg.com.au> wrote


Pursuant to the "Mythbusters" show - how fast DOES a so called " 52
times
" drive actually go ??

The linear track speed of a music CD is from 1.2 to 1.4 m/S - which on
the inner diameter of 50mm gives an rpm range of 458 to 534 rpm.
Multiplying those numbers by 52 gives an rpm range of 23,816 to
27,807
!!


Where is the catch ?


*** Probably in the "by 52" Area. By 52 of what?

Brian Goldsmith




................ Phil
Click to expand...
 
On Tue, 1 Feb 2005 17:28:11 +1100, "Phil Allison"
<philallison@tpg.com.au> wrote:

Hi all,


Pursuant to the "Mythbusters" show - how fast DOES a so called " 52 times
" drive actually go ??

The linear track speed of a music CD is from 1.2 to 1.4 m/S - which on
the inner diameter of 50mm gives an rpm range of 458 to 534 rpm.
Multiplying those numbers by 52 gives an rpm range of 23,816 to 27,807
!!


Where is the catch ?

We've actually had a disk let go in one, they promptly replaced the
Click to expand...
drive. The drive seemed a bit off balance when we got it. Perhaps
that's one of the causes of exploding CDs. Find some of the cheap
magazine disks we had would easily break when touched the edge on a
grinding wheel. Seems any small flaw sets them off. I was surprised
more people have not had the wheeeeeee-- bang tinkle.

Al

I don't take sides. It's more fun to insult everyone.
http://kwakakid.cjb.net/insult.html
 
"Phil Allison" <philallison@tpg.com.au> wrote in message
news:368lrqF4t33gvU1@individual.net...

The linear track speed of a music CD is from 1.2 to 1.4 m/S - which on
the inner diameter of 50mm gives an rpm range of 458 to 534 rpm.
Multiplying those numbers by 52 gives an rpm range of 23,816 to
27,807
!!
Click to expand...
Some good info here, from people that you would think would know -
http://www.liteonit.com/ODD/English/e_service/e_cd-rom%20faq.asp

Check out Q3 - max RPM is only 10K, even for 50x drives (using mix of CLV
and CAV)
 
"Alan"
"Phil Allison"

The linear track speed of a music CD is from 1.2 to 1.4 m/S - which
on
the inner diameter of 50mm gives an rpm range of 458 to 534 rpm.
Multiplying those numbers by 52 gives an rpm range of 23,816 to
27,807 !!

Some good info here, from people that you would think would know -
http://www.liteonit.com/ODD/English/e_service/e_cd-rom%20faq.asp

Check out Q3 - max RPM is only 10K, even for 50x drives (using mix of CLV
and CAV)
Click to expand...

** Mystery solved - thanks Alan.

The sites I looked at were riddled with erroneous information - some said
the 1x data rate was only 150 kb/s instead of the correct 150 kB/s. Others
quoted absurd max rpms in the 27,000 to 30,000 range for 52x and 56x
ives - ie the same speeds the things are known to disintegrate at !!


BTW

A point on the edge of a CD spinning at 30,000 rpm travel at 204 m/S ( Mach
0.6 ) and experiences a force of 65,000 g.




................. Phil
 
"Lord-Data" <data@ihug.com.au> wrote in message
news:41ff40fc$0$346$61c65585@un-2park-reader-02.sydney.pipenetworks.com.au...
52x of Single speed .. which, for data, is 300k/sec ..
Click to expand...
Um, 150k/sec, sorry :)


I don't think audio is the best measure, because it is always played at 1x
.. reading it, as in ripping audio, at higher speeds no longer needs to
maintain a linear speed throughout the disc ..

Google up on CAV and CLV.. 2 different methods of disc speed control ..



"Brian Goldsmith" <brian.goldsmith@nospam.echo1.com.au> wrote in message
news:4KFLd.143561$K7.112149@news-server.bigpond.net.au...

"Phil Allison" <philallison@tpg.com.au> wrote


Pursuant to the "Mythbusters" show - how fast DOES a so called " 52
times
" drive actually go ??

The linear track speed of a music CD is from 1.2 to 1.4 m/S - which on
the inner diameter of 50mm gives an rpm range of 458 to 534 rpm.
Multiplying those numbers by 52 gives an rpm range of 23,816 to 27,807
!!


Where is the catch ?


*** Probably in the "by 52" Area. By 52 of what?

Brian Goldsmith




................ Phil
Click to expand...
 
On Tue, 1 Feb 2005 21:29:50 +1100, "Phil Allison"
<philallison@tpg.com.au> wrote:

"Alan"
"Phil Allison"

The linear track speed of a music CD is from 1.2 to 1.4 m/S - which
on
the inner diameter of 50mm gives an rpm range of 458 to 534 rpm.
Multiplying those numbers by 52 gives an rpm range of 23,816 to
27,807 !!

Some good info here, from people that you would think would know -
http://www.liteonit.com/ODD/English/e_service/e_cd-rom%20faq.asp

Check out Q3 - max RPM is only 10K, even for 50x drives (using mix of CLV
and CAV)



** Mystery solved - thanks Alan.

The sites I looked at were riddled with erroneous information - some said
the 1x data rate was only 150 kb/s instead of the correct 150 kB/s. Others
quoted absurd max rpms in the 27,000 to 30,000 range for 52x and 56x
ives - ie the same speeds the things are known to disintegrate at !!


BTW

A point on the edge of a CD spinning at 30,000 rpm travel at 204 m/S ( Mach
0.6 ) and experiences a force of 65,000 g.

I once witnessed (late '70s) a 9" cutting disk/disc on a hand held
Click to expand...
grinder let go at much lower speeds and a large piece went right
through a welding helmet and split the guys nose.
I just checked a new disk and the ones I have are max 6800 rpm.
Badly stored or handled, incorrect mounting, getting stuck/jammed in
the work seem the main reasons for failure.

This may be an industrial myth but I was told about a young bloke sent
out to cut steel plate, didn't know it was propped up by an acetylene
bottle, they apparently didn't find much to bury.

Al

I don't take sides. It's more fun to insult everyone.
http://kwakakid.cjb.net/insult.html
 
Albm&ctd wrote:

On Tue, 1 Feb 2005 21:29:50 +1100, "Phil Allison"
philallison@tpg.com.au> wrote:


"Alan"
"Phil Allison"

The linear track speed of a music CD is from 1.2 to 1.4 m/S - which
on
the inner diameter of 50mm gives an rpm range of 458 to 534 rpm.
Multiplying those numbers by 52 gives an rpm range of 23,816 to
27,807 !!

Some good info here, from people that you would think would know -
http://www.liteonit.com/ODD/English/e_service/e_cd-rom%20faq.asp

Check out Q3 - max RPM is only 10K, even for 50x drives (using mix of
CLV and CAV)



** Mystery solved - thanks Alan.

The sites I looked at were riddled with erroneous information - some said
the 1x data rate was only 150 kb/s instead of the correct 150 kB/s.
Others quoted absurd max rpms in the 27,000 to 30,000 range for 52x and
56x
ives - ie the same speeds the things are known to disintegrate at !!


BTW

A point on the edge of a CD spinning at 30,000 rpm travel at 204 m/S (
Mach
0.6 ) and experiences a force of 65,000 g.

I once witnessed (late '70s) a 9" cutting disk/disc on a hand held
grinder let go at much lower speeds and a large piece went right
through a welding helmet and split the guys nose.
I just checked a new disk and the ones I have are max 6800 rpm.
Badly stored or handled, incorrect mounting, getting stuck/jammed in
the work seem the main reasons for failure.

This may be an industrial myth but I was told about a young bloke sent
out to cut steel plate, didn't know it was propped up by an acetylene
bottle, they apparently didn't find much to bury.

Al
Click to expand...
Wandering offtopic, you get massive explosions when compressed gas is heated
and explodes: boiling liquid expanding vapor explosions (BLEVE)
http://www.epa.gov/superfund/programs/er/resource/d1_22.htm

gtoomey
 
Albm&ctd wrote:

Find some of the cheap
magazine disks we had would easily break when touched the edge on a
grinding wheel. Seems any small flaw sets them off.
Click to expand...
Brttle materials like acrylic and glass fracture suddenly around small
flaws, such as chips and scratches.

This is because the stress in any material is inversely proportional to
the radius of curvature of the surface, so inside a nick or chip, the
stress is thousands of times higher than it is elsewhere. (Which is why
jet aircraft windows and ship hatches have round corners.)

It doesn't have to be visible, either. A microscopic bubble will
probably be enough. It could even be there from the manufacturing
process.

This probably explains why not all CDs fail this way. They'd need a
defect in the right spot for the stress to make them fail.


-- Phil
 
Wandering offtopic, you get massive explosions when compressed gas is
heated
and explodes: boiling liquid expanding vapor explosions (BLEVE)
http://www.epa.gov/superfund/programs/er/resource/d1_22.htm

gtoomey
Click to expand...
Not quite a BLEVE but many years back, someone put one of those disposable
liquid propane/butane canisters in a campfire - after the bang the birds
went quiet for quite a while, it made a nice mushroom cloud & put the fire
out at the same time.
 
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