Butchering 120mm CDRs into 80mm ones

I have a Sony CDMavica digicam that writes to 80mm CDRs (but not CDRWs).
I’ve been given 4 of them with it, but they aren’t going to last long at the rate I take pictures, so I need more.
The problem is that we have a tax here that makes buying blank media very expensive. A simple 120mm CDR can’t, by law, cost less than €0.5.
Of course, unusual items like 80mm CDRs are hard to find and even more expensive than 120mm ones. The only shop I’ve found that stocks them wants €1 for each.

Not wanting to give in to this madness I tried online shops in other countries, but while they have much saner prices they want some €13 for shipping, even for one tiny 10-cd spindle, so they are out too.

Then I started thinking… I have lots of TDK supercheap standard 120mm CDRs I bought long ago on a trip to Switzerland. I used some, then got a DVD writer and had no more use for them, so I left some 50 of them in a cupboard and pretty much forgot about their existence.
Is there any way to “convert” them?

How would I go to resize them? I know from experience that standard cutting methods (knives, dremel…) create cracks on the delicate reflective layer, pretty much making the whole disc useless. Perhaps with a hot knife? The discs don’t spin very fast at all in the digicam, so it wouldn’t be a problem if they weren’t perfectly balanced and/or round.

Also: once they were cut to size, would I need some sort of hack in order to get the digicam to read them, or would it adapt and just burn them as standard 80mm CDs? I suppose it’s smart enough to know its drive couldn’t possibly read a full 120mm disc…

Your quest to convert 120mm CD-R media into 80mm CD-R media is doomed.

None of your tools is going to be able to to perform such an operation, and in the unlikely event that you should be able to somehow cut a CD with precision laser equipment (and I’m not saying it can be done), you would have a CD-R that would still have the original ATIP information of an 80 min CD-R.

The best you could hope for is a colossal waste of time, and no damage to your Sony CDMavica digicam.

The worst that could happen is a colossal waste of time and a Sony CDMavica digicam that you have destroyed by using your self-made 80mm CDs.

P.S. I hope this wasn’t just your idea of humour! :wink:

8 cm CD-RW media can be had for quite acceptable prices those days, at least in Europe. Want me to send you some? :wink:

Do I really need precision laser equipment to cut polycarbonate? Is there nothing that’ll keep the reflective layer on?

you would have a CD-R that would still have the original ATIP information of an 80 min CD-R.

True, but from reviews I’ve read it seems the CDMavica treats every cd as a 156 MB one, even formatting higher capacity ones (such as 210 and 220-MB ones) to 156 MB. I can see no reason why it wouldn’t treat a 700-MB disc in the same way.

The worst that could happen is a colossal waste of time and a Sony CDMavica digicam that you have destroyed by using your self-made 80mm CDs.

How could I possibly damage it? The worst I think can happen is a “incompatible disc” or some such message…

P.S. I hope this wasn’t just your idea of humour!

Not at all, although I can see why you’d think this :stuck_out_tongue:

I’ve no use for CD-RW media. My digicam is a CD1000, the first generation of CDMavica, which is only compatible with non-rewritable CDRs. But if you can give me prices for 80mm CDRs for Europe including shipping, I may be interested…

10 can be had for about € 5 at some webshops, S&H not included :frowning:
Will look at the Saturn and Media Markt shelves with more attention next time!

I’ve had partial success.
I used some glue on the disc to keep the reflective layer on, then used the Dremel with the cutting tool to cut off the outer part of the disk.
The result looked a bit agricultural, but it fit in the digicam’s drive.
It was an old disk that had gone bad long ago, so I was rather surprised when the digicam initialized it. It couldn’t write any image, of course, but the mere fact that it accepted it and tried to initialize it makes me optimist about using discs with an ATIP that it isn’t supposed to recognize.

I tried again, but the big problem is that I either cut too little of the outer part and the disk doesn’t fit, or by cutting closer to the center I lift some reflective layer too near to the data part.

I need a better way to cut the disk. I was thinking of finding a 8cm wide metal pipe, heating it on the stove and pressing it on the disk…

If you want to risk your cam, just as a hint some CD-R will work much better than others, depending on the manufacturer and the representation (silver top, or branded).

Why would I risk my cam, again? What could possibly happen that would damage it?

Wow, never heard of anyone trying that. Learn something new every day :slight_smile:

As to the discs, what everyone would be afraid of is a bit of the discs breaking off when it is spinning at high speed and destroying the insides of your camera. You should put your results up on the web. Would be very interesting to see.

even 8cm DL media is now available.
Why sacrificing 12cm dvds when it will not work anyways??

I like trying new things. :stuck_out_tongue:

As to the discs, what everyone would be afraid of is a bit of the discs breaking off when it is spinning at high speed and destroying the insides of your camera

It’s not spinning at high speed at all in the camera.
The burner in the CD1000 is rated at 4x speed; that’s quite slow. When I tried the roughly-cut disc I mentioned above you could clearly feel the camera shaking a bit as it was spinning the disc, but it’s nowhere near what happens when you feed an unbalanced disc to a 52x reader. I’m pretty sure 4x isn’t enough to break a disc, at least not if it doesn’t already have cracks all over it.

You should put your results up on the web. Would be very interesting to see.

I’ll do that :smiley:

Because a blank 120mm cd costs me 20 cents, while a blank 80mm cd costs me 1 euro.

Anyway… I’ve given up on the dremel. It clearly it isn’t the tool for the job; the results are rough and unpredictable, and so far of the 5 discs I tried to resize I only managed to make one that would fit in the camera without ripping up the reflective layer. A failure rate of four in five is unacceptable.

I’ve thought about it, and later today I’ll break out the angle grinder. Stay tuned.

Anyway… I’ve given up on the dremel.

If you could mount the disc in say, a drill press, & lower it onto a blade, set to cut at the right dia., it seems that it would work.

wear safety glasses

katz :slight_smile:

Which country are you living in, [B]Fallingwater[/B]?


Ok, things I’ve learnt so far:

  1. it’s not easy to balance a cd on the spindle of an angle grinder that’s slightly thinner than the hole in the disc itself. It’s actually what is taking the most time
  2. it’s even harder to keep an x-acto-like knife in position as the disc is spinning without it bouncing all over the place and ripping up reflective material in random areas of the disc. However, adding weight to the blade makes it much easier: I’ve gripped it in a 3-kg bench vise which I lower by hand on the disc. It’s much more stable, but still not perfect, and I always end up not cutting exactly where I want
  3. light clothing isn’t enough to protect you from cd shards flying at high speed. I was actually starting to wonder how come I hadn’t hurt myself yet… now the great tradition of drawing blood every time I use a power tool has been kept intact :stuck_out_tongue: let’s hope I can continue the experiment without loss of life or limb…

At least you need to wear protection glasses, and preferably a mask, as you need to protect yourself from metallic dust. You don’t want to breath them… :wink:

More than breathing them, the problem is that after cd cutting sessions I look like a young teenage girl who used too much of her glitter makeup :stuck_out_tongue:
You’re right, though, I should definitely get some form of eye protection… I’ll go buy some today, should have done it long ago too.

Anyway: the main problem here is that I should have both the grinder and the blade at a fixed position, and be able to lower the blade always on the same position on the disc. I’m consistently failing to do this by hand, and the resulting discs are either too small, too large or all ruined.
Of course I don’t have a proper blade holder… I’ll try to rig something up with the bench vise. Perhaps keeping the blade steady as I hand-hold the grinder will prove easier. Will have to be careful about not letting shards hit my hands though.
I’m also running out of old unreadable discs to perfect my technique on… I don’t want to waste perfectly good blank media.
Hmm, I think it’s time to dig out all those cds that ISPs used to give out for free some time ago…

I remember when a friend of mine broke his playstation. He ripped out the CD motor and hooked a 9V battery to the wires, thing spun up like mad.
He also at mounted a CD cut to look like a buzz-saw, I still have a scar on my arm from when he decided to flick said CD off the motor while it was spinning, but that’s beside the point, hehe. :doh:

I was thinking if youre daring enough to rip apart a dead CD player, prefferably one that has the “grip” type of spindle (like most cd walkmans now)
you could mount the motor to something sturdy, mount a CD onto it, and pipe a few volts thru it. You would have something, when paired with a dremel or something, to potentially create a smooth surface to trim the disc down to size.

I take no responibility for any flying buzzsaw discs that may result from this :bigsmile:

Motors in CD players/burners/readers/whatever are brushless units. I don’t know how your friend managed to get his to spin, but brushless motors require electronic control to spin (which is why computer fans always have some circuitry in them). Putting some voltage across their terminals won’t be enough, and they always have more than 2 terminals anyway.
Besides, motors in players aren’t designed to provide any kind of torque. They have to spin the disk in the air, not against a blade cutting into it. They’d just not be powerful enough.

But spinning the disk is no longer the problem; the angle grinder does that just fine, and seen how it’s designed to cut metal and masonry it has more than enough torque. The problem is that I have to find a way to keep the blade on one precise position on the disk for as long as it takes to cut it (generally a few seconds).

I’ve learned more things.

  1. the idea of holding the grinder against the blade sucks. I keep moving the thing and borking the cut.
  2. it pays to apply the blade slowly. I now keep the grinder on the ground and lower the whole vise (which is gripping the blade) on top of the spinning cd, letting gravity do the rest. This has given promising results.
  3. the blade I’m using is very soft. It’s meant for cutting paper and other soft things, so when used to cut hard plastic it heats up very quickly and becomes awfully easy to bend.
  4. I need to firmly affix the grinder to the ground. Left free it tends to move around as the blade offers more resistance, and this causes blade bending and more borked cuts.
  5. glue on the reflective layer makes things worse. CDs cut without it have an intact layer a millimeter or so from the cut, while cds cut with it have cracks and blobs of lifted layer almost half a centimetre in.

I believe once I find a way to keep the grinder still and replace the blade, I should finally get some results.

I’ll conduct more experiments tomorrow. Stay tuned.

LOL! :bigsmile:

I’m intrigued by this thread, and dying to know how things turn out.

Just please be careful, as people have said…or we’ll have to start teasing you for wearing glitter makeup :bigsmile: