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

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