hard drive platters and rare earth magnets

[keith ouellette]

Being rather low on cash and having more time than money I started taking apart hard drives for the aluminum. Its a poor way to make extra cash.

The magnets and platters (the platters are the round supper shimmy disks in the hard drive) are only worth 10 cents per pound as scrap.

Has anyone heard of them being sold in any other way?

The guy I got them from sells hard drives (the source of the hard drives) and doesn't need them for anything.

[Guy Mathews]

Being rather low on cash and having more time than money I started taking apart hard drives for the aluminum. Its a poor way to make extra cash.

The magnets and platters (the platters are the round supper shimmy disks in the hard drive) are only worth 10 cents per pound as scrap.

Has anyone heard of them being sold in any other way?

The guy I got them from sells hard drives (the source of the hard drives) and doesn't need them for anything.

Out of curiosity, what happens to the magnets? How big are they?

Guy

[keith ouellette]

Out of curiosity, what happens to the magnets? How big are they?

Guy

The magnets ae different sizes but the majority are about 1+1/2" long by 5/8" wide and roughly 1/16" thick. each one is bonded to a piece of steel a little larger than the magnet. (they are an odd shape, likeif you cut off a section of a donut)

As to what happens to them. Right now the best I can come up with is 10 cents (maybe 5) per pound at a recycle plant near me.

By the way. They are really strong. I got my finger pinched between two of them.

[JohnT Fitzgerald]

Keith, are you talking about the recording heads? or it might be part of the 'actuator', that moves the head back and forth. Or maybe the motor itself...

FWIW, you might want to research exactly *what* is inside those drives. I would think the platters with their magnetic coating would be harmless, but there is bound to be some oils and lubricants, especially in the motor assembly.

[keith ouellette]

Keith, are you talking about the recording heads? or it might be part of the 'actuator', that moves the head back and forth. Or maybe the motor itself...

FWIW, you might want to research exactly *what* is inside those drives. I would think the platters with their magnetic coating would be harmless, but there is bound to be some oils and lubricants, especially in the motor assembly.

I'll be honest. I have no idea what those things are:)

All I know is turn a bunch of little screws and find the parts that are aluminum.

The platters are the round mirror like disks in the hard drives. I'm guessing its what all the data is stored on. They are kinda neat and are like perfect mirrors.

[Bryan Morgan]

There isn't any oils or anything inside hard drives. I take these things apart all the time at work. I manage networks and servers for a living. :) There are two magnets that sit on either side of the head assembly. The magnets themselves are usually attached to some kind of metal mounting plate. The magnets are neodymium. Heres an explanation and a picture: http://en.wikipedia.org/wiki/Neodymium_magnet They are probably the most dangerous parts of the drive. 1. for being so strong you get pinched. We took apart some old hard drives from the 80's and those suckers were quite big and extremely strong. My co-worker got pinched so hard it split his skin and he bled all over the place. We'd keep one in each hand and move them together until they flew together making sparks and whatnot. 2. They have some kind of protective coating on them. I've read its bad for you to handle them if they don't have this coating... gets into your bloodstream or something. 3. Keep them away from your credit cards. Weak magnets like your typical kitchen magnet won't harm your cards but these rare earth magnets will wipe them clean. Mythbusters did this one.

I use those magnets for all kinds of things. Fridge magnets, etc. I put them on my power tools to hold any small tools that go with it. For example, I put one inside the top door of my bandsaw to keep the allen wrench I use for my guides. I put one on my drill press to hold the chuck key. We have metal cubicles at work and these hard drive magnets are stuck all over them holding up papers.

The motors can be useful if you are good with electronics. I know people on the R/C forums rewire them and use them in their R/C airplanes and helicopters. They are brushless and quite powerful. I've used the motors from CDROMs for this myself in some helicopters. There are also some very nice bearings that are removable in some drives that you can use for your R/C hobbies.

We give the platters to one of the guys we work with who is a martial arts instructor. Believe it or not he uses them to train guys to throw shuriken. Some platters we've come across aren't metal, they are a weird glass like material that shatters into a million pieces if you aren't careful.

I haven't come up with any good uses for the circuit boards. I work on electronics but not SMD devices.

I found this about the neodymium:

"
Neodymium metal dust is a combustion and explosion hazard. Neodymium compounds, as with all rare earth metals, are of low to moderate toxicity; however its toxicity has not been thoroughly investigated. Neodymium dust and salts are very irritating to the eyes and mucous membranes (http://en.wikipedia.org/wiki/Mucous_membrane), and moderately irritating to skin. Breathing the dust can cause lung embolisms (http://en.wikipedia.org/wiki/Embolism), and accumulated exposure damages the liver. Neodymium also acts as an anticoagulant (http://en.wikipedia.org/wiki/Anticoagulant), especially when given intravenously.[6] (http://en.wikipedia.org/wiki/Neodymium#cite_note-history-5)
Neodymium magnets have been tested for medical uses such as magnetic braces and bone repair, but biocompatibility (http://en.wikipedia.org/wiki/Biocompatibility) issues have prevented widespread application. Commercially available magnets made from neodymium are exceptionally strong, and can attract each other from large distances. If not handled carefully, they come together very quickly and forcefully, causing injuries. For example, a person lost part of his finger when two magnets he was using snapped together from 50 cm away.[13] (http://en.wikipedia.org/wiki/Neodymium#cite_note-12) Another danger is when two such magnets snap together, the force of the collision can cause them to shatter, sending sharp pieces flying around, potentially causing serious injuries.[6] (http://en.wikipedia.org/wiki/Neodymium#cite_note-history-5)"

[JohnT Fitzgerald]

There isn't any oils or anything inside hard drives

Bryan, I'll trust your experience, but.....my company does a lot of work (development, and also failure analysis/root cause analysis) with one of the major HDD companies. A few years ago, the 3.5" hard drives we were using had a rash of errors......one group of problems caused by a faulty bushing or bearing in the motor, which involved the motor lubricant, and another rash of problems due to the way a lubricant or some type of coating (could have just been a 'coating' was "misbehaving" on the surface of the platters.

I would assume you'd know if you were getting junk on your hands, so you may be right. and that tip on the neomydium mags is a good one - cannnot be too careful!

[Curt Harms]

The light on Rikon 10-325 band saws likes to come loose and is a pain to retighten. I removed mine, mounted it to a piece of angle iron and put 2 H.D magnets on the outside of the other face. Holds great. They will break pretty easily if bent but they are STRONG.

[Dan Friedrichs]

That metal bracket that the magnets are on is usually not affixed to the magnets very strongly. You can stick a flat screwdriver between them and easily pry the magnet free.

[Bryan Morgan]

Bryan, I'll trust your experience, but.....my company does a lot of work (development, and also failure analysis/root cause analysis) with one of the major HDD companies. A few years ago, the 3.5" hard drives we were using had a rash of errors......one group of problems caused by a faulty bushing or bearing in the motor, which involved the motor lubricant, and another rash of problems due to the way a lubricant or some type of coating (could have just been a 'coating' was "misbehaving" on the surface of the platters.

I would assume you'd know if you were getting junk on your hands, so you may be right. and that tip on the neomydium mags is a good one - cannnot be too careful!


I actually need to step back and admit I was wrong about the oil thing. I didn't even think about the hard drives that have fluid bearings as a "feature". I've disassembled easily over 1,000 (maybe a few thousand... I don't pay attention. I just destroy them for policy reasons and salvage the parts I think are cool) hard drives and have never seen any kind of oil substance, even drives with the fluid bearings. There are sealed bearings in there which I would think could contain some kind of lube but I've never seen one fail. If a bearing seal broke I could see its contents coating the platters due to centrifugal force. What kind of hard drive was this? Was it recent?