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Magnets from Hard Drives

or: Destroying Old Hard Drives For Fun

 

This isn't exactly woodworking...

Magnets are cool, and fun, and they are also very useful around the house and around the shop. Rare-earth magnets, are in particular very powerful despite their small size, and useful in many projects. For instance, I have magnets in my featherboards. I use magnets when changing my DC bag to help hold things in place. We use magnets to hold notes to the door, and so on and so on...

What you may not know, is that computer hard drives (aka: hard disks, or HDs) contain two powerful magnets.

Virtually everyone has a computer these days. Actually, most of us are on our third (or fourth or..) computer by this point. If you're like me, your old computer is probably still stashed away in the basement, since you kept it "just for a bit" after getting the new computer, and you've never gotten around to tossing it.

But before you take it off to your electronic-waste recycler, how about you first have some fun and retrieve the magnets from the disks.

This photo essay is about how to disassemble a typical HD in order to extract the magnets. I will also show how to make a simple magnetic hook out of the result.

Start with an old or broken HD that is destined for the recycling bin.

I am fortunate in that I work at a university and have access to a whole bunch of old HD's that are being scrapped and tossed into the recycling bin. These are 10+ year old units, either too old, too broken, or too small for continued use.

This is the top side of the HD. This is what we need to remove to access the innards. As you can see there are several torx screws holding it closed.

There are actually more screws than you see. The sticker on the HD covers up usually two or more screws. If you push on the sticker with your finger you can usually find the indentations (I shaded them in with a pencil and circled them to make them visible in the photo).
And here I have peeled back the sticker and removed the various covers, revealing all the torx screws -- there are TEN holding this HD closed. They really don't want you getting in there. (And of course normally you don't want to get in there, they are sealed to protect your data!!!)

This is the one tool that you may need to buy.

You will need a screwdriver with the correct size (it's quit small) torx bit on the end. I have access to a multi-tool, which has many sizes of torx tips. Even so, I need the smallest tip in order to be able to loosen those screws.

First of ten screws being removed.
On this drive there was yet another screw that was even smaller than my smallest available torx bit.
Fortunately, a bit of brute force prying was enough to rip off the cover.
Go ahead and force it. You don't care about this drive anymore, otherwise you wouldn't be taking it apart! There may be a thin bead of silicone (or similar) as a sealant around the edges of the lid holding it down.

Hopefully on your drive you won't have to get sou forceful, if you can manage to remove all the screws.

Here is the inside. It was hard to photograph for some reason. The HD platters are polished to a silver mirror finish, and very reflective. I had to severely tweak the contrast/exposure/etc settings on the photo to make this somewhat visible.

On the left are the highly-reflect platters. If you can get those out, they make interesting little mirrors. Above (and below) the platters are the read/write heads on an arm which moves in and out. This is how your data gets onto and off of the hard drive. In the bottom right of the photo is the top magnet. Below it is located a thin copper coil, which is attached to the read/write arm. That is how the arm moves, by sending voltages through the coil, which interacts with the magnetic field. Below that is the lower magnet.

(And that concludes the small geeky tech lecture.)

Using a screwdriver to pry out the top magnet. The magnet is no longer attached or fastened in place; it is simply held there by magnetism.
Now, if you also want to remove the bottom magnet, you may have to deal with fasteners on the other side also. In my experience, this is rare, but these drives happen to have them. If so, you would need to flip over the drive, like so...
...and peel back some more covers to reveal still more torx-head screws that need to be removed.
And here is my sample HD with both magnets removed. The read/write arm gets a bit bent. That really can't be helped, as it is most definitely in the way. But it's also very delicate, so it's easy to force out of the way.
And a close-up. The upper magnet is on the left. It nicely has 3 mounting holes, that you can use to fasten it to something. I'll get to that next.

The lower magnet is on the right. These always have some form of bent "legs" (for lack of a better term) sticking up. This makes them a bit harder to work with, if you want to incorporate this magnet into another project. Oh well, that's what hacksaws and grinders are good at removing!

Here is that bottom magnet attached to the frame of my bandsaw. Note that the magnet isn't actually touching! The shaped legs are holding the magnet at almost 1/4" from the metal of the Bandsaw, and yet it is still strong enough to hold. These particular model of HD's have VERY strong magnets.
Just as a proof of concept, I mounted the top magnet to a piece of oak with some screws, and the attached a shaker peg to the other side. The result is a quick and simple project which makes one of the strongest fridge magnets you've ever seen.

I did notice that the magnet like this could easily scratch or mark the surface. I would recommend covering the magnet, perhaps with some plastic tape or some high-friction plastic (Available from Lee Valley) to cover the magnet and protect the surface. I would also consider routing out a recess to sink the magnet flush, or even fractionally below, the surface of the wood where it is mounted.

Here are a couple more photos of that simple project:

Here, I'm using this magnet to pick up another HD that I had ready to disassemble. I have not tried to measure the actual strength of the magnet. For one thing, unless you get the exact same model of HD, any measurement I give you would be meaningless. Suffice it to say, it's STRONG!


This web page has focused just on extracting the magnets. What to do with the magnets is for another day. You could just leave them bare and use them, or mount them on wood as I did, or come up with some other use. I'll be thinking of different ways I can use these around the home and shop.

 

Thanks for reading!