Hi everyone,

I've been playing around with a kit of mine trying to finish it for pics, but the results of one of my items were so good I decided to post it a bit early.

Some of you might be aware on the periphery that the hard drive disk in your computer is likely either glass or aluminum with a magnetic coating. These platters spin at outrageous speeds and can not deform in any meaningful way. Thus they are very resilient, flat, and almost perfectly reflective because of this.

I had a stack of old Jaz disks (Iomega) laying around and realized that they might make a good signal mirror. You can pick up a Jaz disk on eBay for pretty cheap - it really doesn't matter what shape it's in unless it's had a head crash which may scratch the surface. Each Jaz disk has 2 platters, and you can get them as cheap as a buck. One could use an old 3.5" or 2.5" hard drive in much the same manner.

The disk platter works as a great signal mirror. I tested it side by side against a similarly sized Ultimate Survival 2"x3" mirror.


The Jaz signal was much brighter and less "spread out" by the time it hit the target (my porch siding - the Jaz is on the left) 10-12m away.


Keep in mind that the siding is dark gray and absorbs a lot of the light. Reflected against a shiny or white surface, it's actually difficult to look at. It can light up a car's reflectors from a block away without ANY difficulty in broad daylight. I find it to be at least twice as bright as the US 2x3" and I've carried it in my pocket with other metallic objects without much damage. It does not scratch easily, however I would recommend you get a "badge holder" available in any super-mart or office store. The thin pieces of clear plastic make a decent carry and protector for the mirror and they allow it to "signal" even if you are unconscious.


Cost of Jaz disk - $1-2 if you can pick it up locally (no shipping). Cost of protectors: $1.50 for a pack of 20 Wal-Mart specials. Super flat, very thin, and highly portable.

hmm... i got a very similair purpose made "signal mirror" that looks like that. But mine is made of paper with a shiny reflective side. Not the greatest performence, but nice as a backup mirror.

This is solid Aluminum with a nicely rounded over edge... could probably be sharpened for minor cutting duties, but I like it like this for easy handling. It's very stiff and sturdy not to mention light.

Neat idea. I have two defunct WD drives out in the computer graveyard in the garage. Time to see if they'll perform better in this new role!

p.s. - that platter looks to be about the right size to fit inside a screw-on Nalgene bottle lid. Since that's my pack-based survival kit I'll have to give it a shot. If it doesn't fit there, it will surely fit pressed up against the bottom of the bottle, nested within the little metal cup specifically made to fit the end of the bottle. That little metal cup is pretty shiny in its own right.

I have a knock-off bottle, and I don't think the top is the same size as a Nalgene (mine didn't fit like you suggested). It has a diameter of 6.5mm with an area of 30 sq. mm once you subtract the 2mm center. In comparison, the 2"x3" Ultimate Survival mirror is 7x4.5mm with an area of 28.5 sq. mm once you subtract the targeting circle and the corner lanyard notch.

"I don't think the top is the same size as a Nalgene (mine didn't fit like you suggested). It has a diameter of 6.5mm"

Well, that's gotta be just the cutest little bottle on the planet. You'd have to be careful sipping water from one though ... quite the choking hazard I'd think. <img src="/images/graemlins/grin.gif" alt="" />

I'm very careful when I sip. <img src="/images/graemlins/wink.gif" alt="" /> Sorry, I mean those stats as cm. No idea why I put mm.

These are great signal mirrors. I just stopped by the student-run U of I computer store to see if they had any available. They gave me one.....free. Are these like zip drive discs?

Kinda not really. These are IIRC a magneto-optical drive. Zips were pure magnetic, just over grown floppies and just as sloppy.

Yes, they are very similar and made by the same manufacturer, Iomega. They are, however not plastic like the Zip disks which are based off of floppy technology I believe.

I was really impressed with their reflectivity.

UofI? UC campus? Now I'm wondering where my Mg came from! <img src="/images/graemlins/wink.gif" alt="" /> Some lab scraps? *grins*

I'm pretty sure Jaz were pure mag and not optical. Here's the wiki: http://en.wikipedia.org/wiki/Jaz_drive

Okay.. Not sure which obsolete, haven't used in five years Iomega product I was thinking of. My bad.

hehe... I was thinking the same thing when I dug these up. I got a stack of 12 zip 100's, 11 Zaz 1GB, 2 Jaz 2GB, and 2 250MB Zips. All doing absolutely nothing. I intended to get rid of them on eBay, but the cost of shipping is far more than the item price. Maybe should strip them down and offer them up here as signals for the same cost, but shipping for a stamp! Either way, I'm done using them.

Just tore open a 250 Zip and interestingly enough it appears to look much like the Jaz platter! I guess it makes sense that they would reuse the size and just change the density.

Gentlemen,

Please look closely at the reflection generated by the StarFlash. This is exactly what I have been complaining about. The computer disk is similar to a glass mirror. The StarFlash's reflection is scattered and not nearly as good as a glass mirror. Also the aiming fire ball is too bright and makes it hard to see the target beyond for proper aiming. The computer disk is clearly superior to the StarFlash. A glass 2"x3" signal mirror is even better!

Let me tell you, Craig, you're SPOT-ON with the brightness of the aiming. It nearly blinded me. I barely looked, but in that split second, it was like looking at a concentrated sun. I tried at various distances from the mirror, but it was too painful. I just did the old focus on hand and brought that to my target.

And the disk is as close to flat as anything you'll find. Those have crazy tight tolerances and although I'm sure the surface is probably a bit ragged under an electron microsope, it feels and looks like polished glass... it's silky smooth and really hard to scratch. Even if you do scratch it, you'd have to do some pretty bad damage to ruin it as a signal reflector.

Wow, another correction. I just pulled apart a JAZ drive and they are about 9.4cm in diameter. The ones I was using were either pulled from a ZIP 250 drive or from an old 2.5 in. laptop drive. Sorry I goofed up. Hard drive platters in general should prove a decent mirror. I have some old 340MB Drives laying about collecting dust.... <img src="/images/graemlins/smirk.gif" alt="" />