Instructables

How to separate the Magnets from an old harddisk

Harddisks have a pair off very strong magnets in it, Unfortunately, they are placed on a metal plate for fixing them in the drive. It's very hard to remove them from the metal without breaking the magnet.
But if you know the trick, it's very easy...
This is the trick:....
 
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Step 3: Bending

Bend now the metal until the magnet is only held by its on force.
Just take it off and you have a very good and strong magnet
Be careful not to bring the magnets to close together, because they could snap and break!
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supah4x0r1 year ago
All of these magnets are apparantly chrome plated, but chrome isn't magnetic, so why does the chrome plate pieces stick?
supah4x0r1 year ago
Thanks so much man, there was recently an e-waste collection by my local council, and I managed to get 43 hard-drive magnets, while snapping 3 screwdriver heads
xzackchange2 years ago
Brilliant. Thanks! I was about to shove em in the oven!
That would have destroyed them sinc higher temps will soften (demagnetise) the neodymum magnets.
CargoDaBard2 years ago
Glad I asked before i destroyed a screwdriver.
zeutstarz2 years ago
This is just what I needed, thanks man!
infob2 years ago
I saw it... LATEEEEEE!
ppatekar2 years ago
great method
antling3 years ago
Glad to find this post. Just extracted 2 pairs of magnets and will do what you did
wow.. this is good tip..
i tried your method and it works lie a charm

wanted to try the dental floss method but mine was epoxied
Darter764 years ago
 I have been taking apart a bunch of junk hard drives from my school and i am wondering what metal the plates are that hold the magnets?  
Ev4 years ago
A few thoughts after working with hard drive magnets:  Magnets lose strength when heated or shocked too much.  Keep away from heat and avoid dropping them or hitting them with hammers. Wrap magnets in duct tape, they'll have more friction if used to hold things to metal and will be safer if they break. Put a bunch in a PVC pipe to pick up metal pieces in a shop or garage, then slide the metal away from the magnets to remove. A couple of magnets in a metal dish is great for holding nuts and bolts.
thank broder
 
Astara5 years ago
I found it much easier after my first try...didn't see this article until few days later and this way seems way harder.

Don't try to *lift* the magnets apart. you need to *slide* them apart.
Many have a bit of glue. I used a thin edged chisel, (though it had a dull point, -- dull might be best, not sure) positioned at corner between metal and magnet. Then used hammer to tap on the wedge, and I EMPHASIZE, *tap* -- gently, until the magnet moves. My first magnet, I hit it a bit too hard and had crumbled magnet.
But after that, I realized a gentle tapping, gradually weakened the glue, until the magnet becomes unglued/detached from the under-side metal. I used Lockjaws or vice-grips to hold the metal while I tapped. You will have to position the end of the chisel by holding the tip until you get it into place.
Be careful not to move it -- it's likely to jump up to the surface of the magnet, and you'll have to reposition.

After that...if you have steady firm grasp and a good set of pliers: recommendations:
1) for pliers -- Crescent, w/blue&grey rubber on handle -- they have a 2:1 force multiplier (grip part moves 1/2 angle for ever 1-unit of handle angle), so that really helps in any holding on, and virtually zero risk over over tightening -- but they can slip, so it takes steady grip.
2) Lockjaw adjustable grip-pressure pliers -- these are great, you can set the pressure of the grip -- and it will be the same grip-pressure no matter what size item it locks onto. my friend was amazed when I set it to the lightest tension -- showed that they closed all the way down to zero -- but then stuck my finger in them and closed them -- same tension --next to nill on my finger! Try that with the better known but third option:
3) Vise grips. Whatever kind you are comfy with. I like the newer easy release/no pinch variety. They have the screw on the bottom you adjust for the each exact width -- taking many tries to get it right, but when you do -- dang -- they can crush things (including your magnets if you use them on the magnet.

I'd suggest the lockjaws or vice grips on the metal part. that way you have a firm grip on that and they won't be going anywhere. Then use the force-multiplier Crescents. Position the ends to one side of the magnet (as opposed to putting them over the center or lengthwise). Put them over a side closed to an edge of the metal. Then rotate the magnet so the edge sticks off the edge of the metal. Once you have that done, most magnes can be pried off by hand -- if not, use the piers. But the idea is to slide it off of surfaces -- not pull it away.

And a note of WARNING -- while _most_ of the magnets are not super powerful (though they are alot stronger than household magnets) beware of 15K RPM SCSI magnets from 3.5" disks -- I had a pair separated by thick metal spaces and used a screwdriver to pry them apart. Upon removing the screwdriver, they snapped back together and caught the tip of my finger -- instant blood blister -- *OOWEE"!... Put a cramp in my typing for almost a day after...It could have been worse from what I've heard..

Good luck, have fun, and be careful!
A*a
olao995 years ago
Thank you, I had broken too much hdds magnets. Your English is fine.
arrowcrest5 years ago
great :-) I think your English is fine.
simplytuff6 years ago
Wow , very nice ! too bad i didnt see this before coz ive already broke 2 hardisk magnets
spinach_dip7 years ago
The weird thing about this is that while the plates you removed seem to be made of steel, they seem to have strange properties. I have one of those super strong magnets salvaged from a hard drive and it has the plate attached. While the magnet side sticks very well to the fridge by itself, when you flip it over, It sticks not at all on the plate side. Now just about everyone has stuck a super strong magnet to the shaft of a screwdriver to cause the shaft itself to become magnetized enough to hold or to pickup a screw, so we know how magnetic lines of force move through most ferrous metals, but the plates on theses magnets seem to be blocking those lines of magnetic force. That means that the metal must be some special alloy, perhaps one of those funky non-magnetic stainless steel alloys. Anyone know anything about this?
The special metal on the back of hard drive magnets is called Mu-metal (en.wikipedia.org). It has some interesting properties.
All steels are magnetic except the ones with an austenitic crystal structure. It is a face centered cubic crystal structure and has a low magnetic permeability, as opposed to ferrite and delta-iron, which are body centered cubic crystal structure with high magnetic permeabilities. It basically comes down to how the electron spins align in the lattice.
I thought that IRON was magnetic and that is would certainly allow the magnet to stick to it but on the other side, no magnetism. I was under the impression that this is a basic property of iron. I could be wrong, wouldn't be the first time.
Iron by itself is ferromagnetic, which is one of it's basic properties, but if you add impurities (even ppm of some additions can have major effects), then you will change the crystal structure, and therefore, the properties, of the material. In general, most pure elements are not economically viable materials (both too costly to produce and don't have ideal properties), and much better materials can be made by adding alloying elements. Any and every metal object that you use everyday is some alloy of two or more metals (and/or other things such as carbon in steel), with copper wires being an exception. Even small impurities in a conductive material will greatly increase it's resistance. So, back to the specific issue at hand: the iron in question is most likely an austenitic steel, which has a different crystal structure than most irons/steels because of the composition and how it was processed, and it is this crystal structure that is "blocking" the magnetic field, because it has a low magnetic permeability.
Very well said. You certainly know your stuff. this is probably what they use to guard against EMPs too I suppose.
sounds like the material they use in speakers for magnetic shielding.
I think this has more to do with the rather odd magnetization of the harddisk magnets, rather than any properties of the metal plate. If you look at this picture here: http://www.wondermagnet.com/images/fpnum2.jpg, you'll notice that the magnet is actually magetized as two magentic zones (with opposite polarity, I think) (indeed, some older disk drives have two separate magnets on each plate.) With metal plate attached, your magnetic field lines are nicely conducted from one to the other rather than normal to (and through) the plate surface, as would happen if you had a single pole of a more typical magent attached.
link busted
Sigh; it got the comma included. Delete manually or try
http://www.wondermagnet.com/images/fpnum2.jpg
somehow I missed that comma, thanks
and for the record, I think you are right.
I was under the impression that all magnets had two poles, as (to the extent of my knowledge) it’s impossible (for the time being at least) to create a monopole magnet (a magnet with only a north or south poll).
BTW, there's some theory that says you COULD have "magnetic monopoles", and that they'd have some interesting and useful properrties. But so far they're just the stuff of science fiction, where they tend to be "magic rocks" (ie they can do nearly ANYTHING. IIRC Magnetic monopoles were the magic rock of choice before nanotechnology replaced it.)
Larry Niven
That's correct. I wondered whether I should modify that "single pole" comment. What I meant was a magnet with poles on opposite sides, so that you could attach only one pole of the magnet to the metal plate, with the other pole just hanging in the air. The disk magnets actually have TWO magnetic regions with opposite poles on each side, so when you attach it to a plate, you're pretty much "shorting" a north pole to a south pole, leaving no field to get through the plate (in a disk drive, this is good, since escaping fields would likely damage your data!)
my knowledge is circa 1987 from intro college physics, so someone please correct me if I'm wrong, but I believe the ferrous plate acts as a 'keeper,' guiding the lines of magnetic flux around. You see the same sort of behavior around 'magnetically shielded' computer speakers.
D'oh! Yea, you are proably right. I just tried my super magnet against the fridge with an regular piece of steel (an electrical "handy box"' cover plate)and it did the same thing. no exotic alloys needed.
Ahar6 years ago
ive got a wuestion. if you break the magnets will they lose their magnet properties or would they be useful just not as powerful?
mattccc6 years ago
nice
soustar6 years ago
honestly, a knife works fine... if you just nudge it in there and wiggle it under the glue... you'll get em free... kinda like an oyster?...
I tried to use pliars, but I only had one pair. So I just hit it with a hammer a few times and it slid of pretty easily. It didn't break, but I broke it when I tossed it at a desk leg and broke in half. Great instuctalbe though.
ccddkkuu7 years ago
Thanks for the ideas and clear pictures, HarryM. Regarding the non-stick odd behavior, it may be pertinent that any material that a magnet will stick to carries magnetic flux through it. Thus a lot less of it winds up on the opposite side of the material, hence it is not very magnetic there. Horseshoe magnets have long been commonly seen with a "keeper" across the poles, a piece of steel or iron that makes a complete loop of metal when in place. They remain stronger, hence the term "keeper", with the magnetic loops channeled contained rather than out in the general space. Electronic circuitry is sometimes contained inside a metal box to keep it safe from magnetic fields, or keep magnetic fields from affecting nearby parts. A Faraday cage is an enclosure of conductive material meant to protect the interior from magnetic fields. The more complete the skin, the more effective. You might put your ultrasensitive electronics in a small one; or make a big one to protect you from radar and cell-phone energy (some do have that issue). Maybe the plates referred to here are acting as shields.
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