Procedure for punching a second index hole on a 5.25" disk

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Harry
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Joined: Wed Feb 09, 2011 9:31 pm

Procedure for punching a second index hole on a 5.25" disk

Post by Harry »

Because Mr. Vince mentioned this on the FAQ, i propose that the correct procedure is mentioned too for people really having that idea, because otherwise the disk may be ruined.

Prerequisites:
1. Make a template of cardboard in the dimensions of a 5.25" disk with a hole where the round index hole belongs on the sleeve.
2. Make a strip of cardboard (1 mm thick) nearly as wide as the spinning hole in the disk SLEEVE and 10 cm long.
3. You need a hole punch like it is used for leather stuff. I have one with a revolvable head of 6 sizes from 1.5 - 5 mm. Use a size of about a normal index hole (5-7 mm).
4. You MUST NOT PUNCH through the thin media itself!

Procedure:
1. Mark the position of the new, mirrored index hole on both sides of the disk.
2. Shift the strip of cardboard between media and sleeve in the direction where the new index hole is being cut (to avoid scratches to the media by the hole punch).
3. Carefully slip the one side of the hole punch between cardboard-strip and sleeve and punch the hole at the marked position.
4. Repeat 2 & 3 for the other side of the disk.

I have done this for quite some disks and the procedure seems to be safe, but use it on your own risk.

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mr.vince
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Procedure for punching a second index hole on a 5.25" disk

Post by mr.vince »

We usually just remove the platter for the original sleeve and place it in one with two holes.

I would never attempt to punch a hole while the media is still in the drive...

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IFW
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Re: Procedure for punching a second index hole on a 5.25" di

Post by IFW »

If you are doing this for preservation... please do not.
The disks were duplicated in a single pass and to get the correct index position they should be dumped in a single pass as well - we can do it and instructions are available on how to modify a drive to do the same.

paulhagstrom
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Joined: Fri Jan 20, 2012 11:46 pm

Re: Procedure for punching a second index hole on a 5.25" di

Post by paulhagstrom »

I'm strongly considering, rather than going to the trouble of punching an index hole, just cutting a wedge in the right place on the back side of the jacket that will reveal the index hole passing by to a sensor in the right place. My feeling is that my attempts to punch the jacket will put the media more at risk than cutting a wedge (and also take forever), and if possible I'd rather retain the familiar jackets, rather than opening them up to remove the platter to an existing double-sided case. I imagine I have to be very careful that none of the jacket's hard plastic ends up pointing inward after the surgery, but is there any other negative to doing it this way? The disks I'd do this to are all either already notched away from being collectible or are just miscellaneous disks of my own work that wouldn't be devalued in the process. Still, it's irreversible, so I'd be interested to know if there is any reason to think that this would be a terrible idea.

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Malvineous
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Re: Procedure for punching a second index hole on a 5.25" di

Post by Malvineous »

When the disk is in the drive, the plastic sleeve sort of rests on the inner media, so if your 'wedge' had any sharp edges I would think it could easily cause scratches and additional friction. So you'd have to be careful to cut probably quite a large wedge so the media can still spin freely. I would think modifying a drive would be much less error prone.

paulhagstrom
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Joined: Fri Jan 20, 2012 11:46 pm

Re: Procedure for punching a second index hole on a 5.25" di

Post by paulhagstrom »

Good point, I'll need to try it on a test disk. And I may well conclude that the risk I take with the (ultimately, replaceable) drive is smaller than the risk I'm taking with the irreplaceable media. I hadn't really considered what happens when the wedge is on the top side, though. The structural weakening that this would cause could well increase the pressure on the media from the top cover, even if I'm careful to leave no sharp edges. I'll proceed with caution, and report back here if I do try it. I have no real drive-modifying experience, but I may give that a try anyway. How about putting the drive on its side? That would at least keep gravity from encouraging the cover toward the media, but I'm not sure whether these drives are designed only to work well in a horizontal orientation.

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mr.vince
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Re: Procedure for punching a second index hole on a 5.25" di

Post by mr.vince »

We recommend cutting the jacket. It's easy and pretty safe. You will need a jacket with two index holes, which you can buy new or just rip from an old disk that you can image first.

Then simply use a scalpel (sharp!) and cut the jacket of both disks open along the fold. If you can, get white cotton gloves for use in labs, which means you can directly take the platter out of jacket A and put it in jacket B.

As the spindle motor will hold the platter in place and the door mechanism will hold the jacket in place, we haven't had any problems with this practice EXCEPT the fact that collectors do not like this technique. :D

paulhagstrom
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Re: Procedure for punching a second index hole on a 5.25" di

Post by paulhagstrom »

Ok, thanks. I think I'm convinced. I'll keep good photographic records. This does sound like the safest plan.

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mr.vince
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Procedure for punching a second index hole on a 5.25" disk

Post by mr.vince »

If the original jacket matters... You can usually cut very careful under the fold, thus unfolding the jacket. It takes a little practice and bending, but this way you can put the platter back and reseal the fold with the right kind of glue. The standard superglue (cyanoacrylate) will _not_ work. You need something that will work with PVC and similar...usually more toxic because it needs to solve the surface of the plastic to reseal it.

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