Flattening a Warped disc

[jjmac]

(grin) ... ideas :)

Trying to think of a method to flatten a dvd disc, acquired via an overseas magazine, an enveloped disc, that has been warped.

Occures because of the way they are stacked during transport.

As it occures due to uneven downward stacking pressures, over a number of weeks ... i'm thinking i may be able to reverse it the same way ... using lots of stacked, flat books, with the disc placed within for a couple of weeks.

Any thoughts on this apprieciated :)


jm

[eadz]

LOL good luck.. Who knows, worth a shot. maybe you want to apply a little heat too ;) Maybe put it in the hot water cupboard under those books. Let us know how you get on!

[jjmac]

Howdy eadz


eadz wrote:
>>
LOL good luck..
>>

:) (grin) ... yes, i know, but, never say die and all that.

Damn dial-up, i would be dead in the ether if it wasn't for mag discs. I tend to get all my large src packages from them. Then just, usually, patch up if required. It makes for an interesting exercise too, editing the appropriate .dsc and .diff.gz files to get a package build out of it (grin).

In any case, i did have some partial success. The disc travels from .uk to .au, and they have recently changed to being placed in a 'wallet' rather than a case.

It was very warped, and made a loudish 'wap wap wap' sound when placed in the dvd drive. Attempting to run a

]$ bzip2 -tvv <path>

on a file, locked the process into multiple read attempts. It couldn't be killed. I had to reboot to free the drive ...

So ... i carefully placed it in the middle of a similar mag and then placed a pile of others on top. Along with some encyclopedias. And left it as such for 5 days, testing it just to day.

I did get a 'partial' result. When looking at it side on with a magnifying glass, it was noticeably improved. Except for the edge area, which still had a slight twist to it.

In the drive, the 'wap wap wap' sound was replaced with an initial, much quieter 'twip twip' then stopped after the drive settled.

Mounting was silent, but on trying the same above command ... the same unfortunate result.

I will try again, but i think i need to spread the pressure out over a wider area, so that the disc edges are applied too, with the consistency of the center. I don't think that was the case with the 'pile of mags' method.

It is in the nature of paper to curl/contain waves. So i'll have to devise something that is truely flat.

An encouraging result though.

If the mag was one of the 'thick' kind it may have travelled better, but it isn't.

A good stiff case !, even with the occasional crack in the plastic due to handling, the disc still is likely to survive.

In any case, i will see ... and hopefully find an improvised recovery for this type of hassle.

What really worries me though, is that i haven't ever seen any posts on this kind of thing anywhere. I can't be the only person it's ever happened to, surely ...

... it kinda reminds me of an old Dillan song in a way :)

>>
maybe you want to apply a little heat too
>>

hmmmmmmmm, :), it is winter. I wonder if summer would work better. A sane room temp probably would help though.

Will post back further results :)



jm

[Harry Kuhman]

What are the publishers saying when you talk to them about this problem that you indicate is very common?

[jjmac]

Hi,


What are the publishers saying when you talk to them about this problem that you indicate is very common?


Their very positive, the disc editor has offered to replace the disc. But it's something that has occured due to transport handling. Uneven stacking, having boxes unceremoniously plompt on top of them in a warehouse etc ...not the publishers.

I don't think i actually said it was common. And i haven't as yet seen anyone posting on a similar theme. I do think it may just be more specific to the way there handled at my end. The people who handle the suburban route i'm on. Contacting the distribution company my end is somewhat futile too.

And it does worry me that know one else seems to mention it too.

I'm trying a second attempt now, but with the book pressure better extended so that the edges get a good downward pressure as well as the center.

I'm going to be optimistic and give it a full week. If that doesn't work then i'll take up the offer for replacement.

I've had a whole lot of strange disc damage problems over the lats year, since last August too. So i'm not that surprised.

Last months edition, in slimline cases ... All the cases i saw in the two (2) newsagents i have local access to (suburban), were all damaged. Corner bent, whole cases twisted. It had to be the result of just mindless stacking/handling from warehouse staff. What other reasons could there be ....

In anycase, if i can reverse it, well, that will be something to keep in mind, if an irreplaceable disc should ever develop a warp from some aspect of it's storage.

If it went one way, then hopefully it can go the other :)



jm

[Harry Kuhman]

Their very positive, .... more specific to the way there handled at my end.
Boy, you people down under sure butcher the Queen's English. You got every from except "they're", which .....

I feel you really should let the publisher replace it, and expect them to do so in the future if it happens again. Even if it's the distributor who is actually doing the harm, they are doing it as the publisher's agent and the publisher is the only one who can put pressure on them. The publisher might also do things to better help protect the CD. If they can stick ten subscription cards inside the magazine, then they should be able to put the CD inside the magazine rather than outside it. Or use a more heavy card stock to protect it. Heck, here AOL comes out with all kinds of ways to package free CDs that they mail out, I've even received one or two in thin metal cases. If AOL can do that with free CDs then a publisher should be able to come up with ome way to protect the CD that you are paying for. If they can't or don't want to spen the money because they figure only a small number will be ruined, then they should certainly make replacements for the ruined ones.

[jjmac]

Howdy Harry,

>>
Boy, you people down under sure butcher the Queen's English. You got every from except "they're", which .....
>>

(grin) fair comment :)

And yes, it isn't my fault after all. It will be interesting to see the result next week. If it's still catus, i'll take them up on that.

Thanks for the input too.


jm

[jjmac]

Had disc under two sheets of glass with a wide encyclopedia on top.

On top of that, four rows of house bricks.

Three, on side, criss crossed for each row.

Left it like that for 10 days or so ...

It did get rid of the warping, or so it seems. The file system seems to work ...

File access is kaputen though (grin) ...

I/O errors, bad sector etc ....

Looks like once its' been bent it's gone.

One can but at least try though :)


jm
http://counter.li.org
#313537

[Cuddles]

jjmac,

Reminds me of the old records, which, were easily susseptable to warpage, for the same reasons, stacked for long periods, incorrectly...

The "not exactly cut-n-dry" method for those, was, SMALL AMOUNT of heat, with the record between two "platters" of either thick sheet metal, or glass.

This method was tauted by "purists" to correct a severe warpage in a record, but, not precise information could I find, like, what TEMP and for HOW LONG.

Not sure if this same "method" passes the same "working" test for CDs and DVDs, due to the different raw materials they use, but, its some ideas...

Good Luck though... You may be treading into areas that no one else has :D

Lady_Cuddles

[jjmac]

Hullow Lady_Cuddles

Thanks for your suggestion. I haven't thrown the disc out so i think i will try that.

hmmmmmmm, how to apply the heat, and for how long. I would expect something like 'luke warm' would be the go there. Just to loosen the medium up a bit, if possible.

dvd pits are ever so more tiny than LP grooves though. And vinyl is by nature, more plastic than resin.

It's strange too, in a way. When one tries to bend a dvd on purpose ... they are just soooo strong :). But just through bad stacking/transport -=- they'll warp as easy as looking at. These dvds' come with a mag from the uk by ship, so there in transit for a fee weeks then dumped in a whare house. Ever so gently handled too, i'm sure not.

>>
not precise information could I find,
>>

Hey :), thanks for even bothering. It is nice of you.


The glass is important, as the correcting pressure needs to be applied evenly. I was encouraged in the improvement in the overall warp after the 'brick' attempt, though a feeble attempt it was. It is now only slight, where as before it was quite pronounced (convexed). But, with a magnifying glass, a slight wobble can still be seen around around the rim.


I guess a player could be made to compensate for the focus loss. Detecting the focus loss, then doing a few test passes to determine what degree of correction would be needed. I'm thinking of a kind of verticle 'tilt correction' facility. I have that built into my pioneer, but thats not good enough for this unfortunately :).


In any case, i'll see if i can figure a way to apply heat with out causing to much damage to everything else around me (grin).

It may take a month or so but i will post back the results.

And thanks again.


jm

http://counter.li.org
#313537

[Cuddles]

jjmac, "how to apply heat", as far as I heard from the "record guru's" I spoke of before, i.e. "purists", was to place the whole enchilada into the oven... again, temp is important, too much, and you might end up with a puddle of goo, too little amount of heat, and you can just be wasting time, gas, electric, etc...

Considering the temps of inside the car, and what can happen when a CD is left in one, in direct sunlight, should give better ideas on what temps should be avoided, and more of a "trial and error" approach taken... Time is another issue, and should be weighed against the amount of temp being used... as I said, it is NOT an exact sceince, thats for sure...

Good Luck,
MS Cuddles
-=- Come to the Dark Side, we have pengions -=-

[Cuddles]

... also, as you said, perfectly "flat" to compress the CD with, is vital. If the surface, or surfaces, are not level/flat, it may transfer to the CD...

I also wanted to mention, that, the idea told to me, was, to "sandwisch" the record "between" two surfaces... in this case, glass - cause it usually is quite heavy, and has less chances of being warped itself, as might be the case with metal plates. You also need to watch that temp in another situation, as the "plates" heat up, they may melt the surfaces of the CD they are touching, not good... Like I said, its all trial and error, and I wouldnt do it to something that is "priceless" or "irreplacable" - not unless you can work out the exact time and temp, ahead of time...

I would even bet, that the people who told me this method, have not tried it themselves either... (they may have been looking for a guinea pig)

As a side note: I did try a "home fix" for scratches on a CD; the idea was to use PLEDGE spray wax, apply a layer on the CD, then wipe as usual, from the center out at 90 degree lines, and with a dust-free / lint-free cloth. It appeared to get the small ones covered, but, on the test CD I used (I basically took the CD, stepped on it, and ran it across concrete for a couple of passes), it didnt recover the surface to the point that read errors were not detected. My first attempt at this was a practice (cd-r) and I ran the CD across the carpet, and then a desk (wood) surface that was not sanded, it removed pretty much all the scratches, and was readable with "minor" read errors. The second test was with the same CD, but outside, as mentioned above about the concrete. The CD surface looked far worse than even the "library rental" CD's that we have borrowed. I would say, minor scratches, but getting read errors, could be resolved with this method (disclaimer: I wouldnt go around making scratched disks, to do this, or, to damage a priceless or irreplacable CD by doing this, without, first, testing this on something that wasnt that important... Individual results, may vary :) )

Heop this helps :-D
MS Cuddles
-=- Come to the Dark Side, we have penguins -=-

[jjmac]

Hi,

I did have a degree of success with the two sheets of glass with a couple of large books, then a number of house bricks on top of that. But there was still sufficient convex to cause the laser to lose its' focus on the outer edges.

MS Cuddles wrote:
>>
Heop this helps :D
>>

Yes, of course ... a facinating tail of the shenanigans of the scientifially inclined (grin)

Is it not curious ... a person may try to physically damage a disc. By jumping on it, throwing it around etc ... and find it quite impossible to break. But then , with out trying it can be damaged.

I think the application of sustained even pressure is the best solution. And probably done around the 20 to 23 degree centigrade room temp mark.

It is amazing too, just how much 'pressure' a pile of paper can deliver. After all ... it is wood/trees/logs really.

I suspect that the substrates arn't elastic either. Probably more plastic and so wouldn't lend themselves to easy reversal.

But i did have some success, so i should rig up some sourght of more serious experiment and test again.

I will be followinh HKs' suggestion in future concerning getting the publisher to replace too.

As said, it had traveled by ship from the european region, and some of the mags from that way do tend to arrive on the shelves with obvious signs of misstreatment.

One way to get a hint on the possibly case though. By looking at the in mag wallet, aside from case discs. Every time a stack of bundled mags gets thrown around, or something else is just dumped on top, it's likely to cause the disc to slide a little in its' wallet. Leaving a subsequent scoring mark were it lies in the wallet as a result. By noticing the number and overlap of those scoreing marks, a general treatment history can be guessed.

>>
I heard from the "record guru's" I spoke of before, i.e. "purists", was to place the whole enchilada into the oven... again, temp is important, too much, and you might end up with a puddle of goo,
>>

I agree with your guess there :)

Besides, it would want to be a sustained heat. Nothing more than a comfortable room temp really. It was winter over here in Sept, so that would have been significant. Damn cold (grin).

Thanks for your thoughts (grin), i can see the picture ... nieghbour looks through gap in bushes ... sees person on there knees draging a cd/dvd face over the concrete. Wonders if they should ask her what it is she is doing ... decides their probably better off not knowing :D :D


Cheers (grin)


jm

[Cuddles]

jjmac,

Yes, I can only imagine what many of my neighbors think of me, and some of my "tasks", the CD testing being only one of many... ( Sometimes I feel like the guy in the Thomas Dolby video, with his exclaims; Sceince! ) - most of the time, I feel like one of those "testers" for UL (Underwriters Laboratories ), where they try to destroy something, or break it at a point no one would ever attempt.

Case in point, even though a CD-R is not readable, a computer coaster, so to speak, I tend to destroy them so they cant be re-used. Most of the time, I break them, which, as you said, can take a lot of force, and usually tends to send shards of plastic everywhere. I have actually had a CD "blow up" inside a CD-ROM drive; my Significant Other likes to borrow music from the library, and rip the songs off of them. Many times these CDs are the worst, they look like someone has misstreated them for many years, but, not as bad as the test CD I used outside. Well, all I remember was her putting the CD into her ROM drive, starting a abcde, and watching the light flicker a few times. About five minutes of trying to get through the same sector on that CD, the drive all of a sudden, spun up to some high squeel sound, and then a very loud POW!

She, as well as I, looked at the drive, then the konsole, and back to the drive, numerous times, till the command on the konsole finally reported: "No media in drive" and aborted.

Attempts to open the drive failed, even with the paper-clip... So, I downed the system, and completely removed the drive, chassis, and was graced with thousands of pieces of plastic within the inside of the drive. Many of the "chunks" had even embedded themselves into the sides of the drive, my guess is, from the force of centrifical outward speed when the disc had shattered. I delicately removed what I could with my hands, and then used a vacuum to get many of the tiny fragments, put the case back on, and re-installed the drive. To this day, it still appears to be running, and reading, fine... ( but, I dont give much trust to it, since it had eaten a disc. )

So, if anyone thinks that this never happens, and it can only happen on an episode of Myth Busters, dont be too sure of yourself... It does happen, and without having to "over-power" some drive to the point no one would ever do. In the MB episode, I think they were testing the myth that a CD could "blow" and project out the shards to the point of killing someone - I can attest, no one died from our blown disc, everything was contained within the drive, though it did cost us... We had to replace the CD we borrowed from the library :(

A very nice "side-step" to another topic... Arent we all testers though??? We are running a Distro, made, from the name of the kid in the movie Toy Story, SID, who was the nice child who destroyed his own, and others, toys. So, basically, we are all testers, by choice... Just some of us, tend to go a little farther in our "testing" than others :)

jjmac, my guess is, as with other things, when trying to "undo" something, requires force, of the opposite it took to "make" it that way... in the case of a metal bar, when trying to "un-bend" it, usually requires more force, more work, and a very delicate nature of getting it back to straight again. My thought on a warped disc is, it is going to require delicate "force" in the opposite direction of the convex, to correct it, and maybe, even, over-force, past the point of center, to get it back to center. Whereas, all of these attempts to correct the disc are all to un-bend it to center, it may require it to be bent past the point of center :?:

Hence, the best results you have gotten is to get it closer to center, and not warped, but not fully... I should also point out, that, if any attempt is made to use "heat" on something, it should be "completely" cooled down before any attempt to remove any weight holding it through the process... i.e. sandwich a CD between glass, heat whole assembly to xxx degrees for xxx minutes, remove heat from assembly, let cool completely, then remove the controlling weight from assembly... I am sure that, removing controlling weight from a "cooling" CD too soon, could render negative results as the CD cools without something to control it from any more warpage...

Oh well... I am amazed, I didnt realize I didnt change my notification e-mail address when I moved, and thought that I just wasnt getting notifications cause there wasnt any, and, here all along, I was just my e-mail problem... Already made many boo-boo's on posting on topics that are more than a few months old... Oh, well...

Good Luck jjmac, if you find a "clear-cut" resolution to this, please inform, I'd be interested in having the knowledge for future,
MS Cuddles
-=- Come to the Dark Side, we have penguins -=-

[jjmac]

Howdy MS Cuddles :)



Yes, i will post further on this, hopefully with a 'successful' result.

I think the general idea of applying an evenly distributed pressure, over time, is about the only solution that could have any real viability.

From there it all depends on what a person has available ... in their shed/garage, etc, to work with.

Going out and purchasing a 2 ton hydraulic press with thermal capabilities ... while i probably would if i could (grin), i don't think it would be normally considered as an option by most people. It would be the go though.

Why spend 250k on a tool like that when a person could get a brand new oscilloscope at a much more reasonable price :) .

Those shards of plastic can be very sharp too .. and there is a real danger of slipping and slicing ones wrist if a person has success and is able to snap a disc. Which i gave my self a scare once doing Very, very risky stuff folks.



>>
my guess is, from the force of centrifical outward speed when the disc had shattered.
>>

(hehe grin)



>>
when trying to "undo" something, requires force, of the opposite it took to "make" it that way...
>>

Yes, the trick is how it is applied. The distributed pressure 'over time' method makes the most sense. One can only imagine what weights are involved when 'stuff' is piled on top of 'stuff' in containers. It boggles me. And the way little things can make such a difference. Like, full gloss spine length wallets are better in this respect to the shorter, more terse kind. And a mag that is reasonably thick, say, finger thickness is much more protected than the thinner mags. And as for soft slim line cases ... very much so not designed for long distance transport.

I have noticed though, that different cd/dvd discs will differ in their thickness as well. Some cds' i got (6) from a company in Sydney, with 'woody' on them when it was released, are noticablely 'thicker' than anything i've seen in a magazine disc. Or a purchased rw/r for that matter So, the initial disc quality would play a big role (thickness). hmmm, kind of goes with out saying i suppose :). If a person had a need to be archiving data to a cd/dvd, and be looking at the long term ... a good 'thick' unit would have to be a good idea.

With the applying heat idea ... a good technique for bending metal bars/pipes ... but a little risky for a cd/dvd. A good reasonable summer temp should be all thats needed there. I have heard of some people puting discs holding sensitive info in microwaves for 30/60 seconds before throwing them out ... so ...


>>
Hence, the best results you have gotten is to get it closer to center, and not warped, but not fully... I should also point out, that, if any attempt is made to use "heat" on something, it should be "completely" cooled down before any attempt to remove any weight holding it through the process...
>>

Good point on the cooling.


Considering the degree of initial warp, which was visible with a magnifying glass ... and the somewhat off the cuff effort ... i'm quite happy that the technique is at least ok. It all just depends on rigging something up thats more reliable. I just took a couple of framed pictures apart and used that glass, putting it on a hard carpeted floor with largish books and about 8 house bricks placed on top. And only for about a week or so ... in a cold room.

Will have to give the device a bit more thought. And the time

Not to worry though ... i've recently discovered that 'grub' has an 'eltorito' 2nd stage loader !!!!, that works with remastering really well yahoooo, i can use the shell if i need variations, and add a few custom option too, finally free, free, free, of impossibly static LiveCD boot targets. I like vga=normal, not vga=791 ... (grin), very bad eyes :)

So now i can redo my knoppix (2006.06.01) 5.0.1 disc. And if i change my mind on options, i wont have to redo it all. All is good.


>>
the CD testing being only one of many...
>>

Never give it up. True science is little understood by the masses (grin)

All The Best :)


jm

[jjmac]

Just following up on this:

I recently read an interesting post from someone who was having the same problem as i, and for the same reasons.

A mag disc being subject to disjoint pressures during transit, causing it to warp/convex. Making it unaccessable.


They placed it on a sheet of copy paper, data side down on a table. Then placed a sheet on the label side as well.

They then applied a steam iron set to 'synthetic' a number of times over it.

When removed it sprung more into its' warped/convex shape, but was immediately placed under the weight of a number of heavy books on the table. And left for a few hours to cool.


Their result:
-----------------
Success !, the disc was flat and fully accessable.

They didn't say for how long they applied the iron, but i would think not very.

I have yet to try it, but hopefully will this week on a saved disc.


What a cool solution :)


jm

[nnigam]

I had a similar problem with a Delorme disk because of their shoddy case. I contacted them and they refused to replace so I stopped purchasing their products.

So you are not the only one to have this problem. You probably are the first to try to repair it. I gave mine up as a loss.

How about supprting the warped edges, and then placing a weight in the center to reverse the warp.

[jjmac]

Howdy


nnigam wrote:
>>
How about supporting the warped edges, and then placing a weight in the center to reverse the warp.
>>

No, not a good idea :)

I did mention above using bricks. That did work a lot of the convex out, but not completely. And it was in the middle of winter too, ie; a very cold room.

I was suspecting that as a problem, there must have been a lot of people scattered around the world having to deal with it. And i was right. And it was only an issue with discs that have travelled long distances in those 'wallets' that mags use. The 'soft' dvd cases are useless for long distance protection as well. A good hard cd case though, even if it does arrive with a crack on the lid, the actual cd/dvd will likely be ok. And at an industry price, they cost next to nothing too.

Folks can get a bit apathetic at times, and it seems that people were just wearing it, that is, not speaking up. But, with a bit of probing, getting some discussion happening ... some good ideas resulted. Just goes to show that online discussion does work.

I like the steam iron idea. It means the heat input be comes very controllable. Starting with a small blast, and bringing it up from there as needed. The disc just needs to be protected from the direct steam blast, thus the sheet(s) of copy paper. A person certainly doesn't want to dissolve the label off.

:)


jm