I have a nice shiny disc, extracted from an old HDD, that I want to cut up and re-purpose. It is aluminium (I've already drilled it, so that is confirmed), but I want to cut a couple of straight sections. Although I have a Junior hack-saw, and a fret-saw I think the easiest way would be to run the disc through my little diamond-wheel tile cutter (Plasplugs). But will this work - will it cut the aluminium and/or will it knacker the saw-blade?
In message snipped-for-privacy@4ax.com, Chris Hogg snipped-for-privacy@privacy.net writes
When I tried cutting aluminium with an abrasive disc I found the grit clogged with smeared/melted ally.
My idea to defeat burglars using battery angle grinders: Tungsten/Aluminium sandwich padlock hasps:-)
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Pure aluminium being rather soft tends to clog cutting edges badly. I think you would be better off sacrificing a cheaper cutting tool.
My suggestion would be use a decent sized hacksaw to cut it. Or a small battery powered saw if that is more convenient. Expect to wreck the blade to clogging and/or possibly have to clean it with a wire brush.
So you making a Baird Televisor or what? Brian
wood saws work on ally
Presumably the ally disc supported the steel one? You can't record onto an ally disc.
A decent tipped wood cutting circular saw will cut ally nicely.
AIUI the ally disc is coated with a thin layer of iron oxide - hence the term 'spinning rust'. It certainly punched and drilled as if it were soft ally, and it's not magnetic, in as much as it's not attracted by a little red horseshoe magnet.
If I had a wood cutting circular saw...
Thanks for the replies - much as I suspected, there is a real risk of clogging the diamond wheel. I'll stick with the fretsaw.
The media is plated on.
Choices for disc substrate can be glass or aluminum. One of those choices is under consideration as platters become thinner in 14 or 16TB drives. (The push is on, to stack more and more platters, in the Helium filled drives. Regular drives are at atmospheric pressure and contain "plain ole air". The Helium drives no longer have a breather hole and are sealed.)
Modern PMR discs, consist of a number of layers. PMR has a "keeper layer", which is the end of the vertically oriented bit cell. It completes the magnetic circuit.
The layers above are finished to a very flat finish, to around
2nm roughness or so.The top of the media layers is covered in an organic material similar to a polymer finish on a car paint job. It includes a free radical getter, which is there to make the coating last longer.
These materials will provide no problems at all while you're sawing through the (majority) aluminium material.
The HGST (former IBM employees) site, contained technical articles for the public, on various aspects of disk drive design, and was really the only good source of info. And it's gone now that HGST was acquired by Western Digital. No more sweet articles showing the details. All left to guess work now. The patent filings have more info than an HGST article, but the HGST article was a simple introduction to certain topics. And the patent filings, you have to know which ones are real and which are bullshit, to figure stuff out. Like, one patent claims the flying height is 3nm, and I have trouble believing that one is in production. When the surface finish has an amplitude of 2nm.
They tried to land the heads on the disc on the platter, and with the lubricant finish, the heads lasts through a whole month of rotations, before the heads were ground off and non-functional. So they have toyed with the idea of reducing the flying neight to "zero". I'm sure the platters make that "singing noise" for the whole month :-) Angle grinder.
Paul
You can cut ali with carbide toothed saw blades - so a mitre saw or circular saw (or table saw) will cut it easily.
Grinding discs test to clog unless you have one designed for ali)
Hard drive platters tend to be either ali or glass these days. Its the coating that is ferromagnetic.
Jigsaw, with a hacksaw blade in it?
Think a hacksaw is your best bet, then.
You do it much the same way as you reoord on plastic tape, only a thinner layer of oxide because the track is much finer.
As long as you cut it wet, I'm sure the diamond disc would be fine. Take it slow and gentle :-)
Cheers, Jim
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