Picture of Securely erasing a hard disk
When disposing of an old hard disk, it might be tempting to simply throw it in the garbage, or sell it. However, first you should remove any sensitive data from the disk. This might be financial data, old email, login information for web sites, and the like. Unfortunately, simply deleting files doesn't normally remove the data -- it just marks the space as available and removes the file from the directory listing. The data can be recovered at this point, often quite trivially. If you wish to protect your data, you need to do something more thorough. There are some software utilities that can do a fairly good job, but if you're feeling especially paranoid (or simply want to have fun!), a physical process is required.

Please note that casting is a potentially hazardous activity. Observe appropriate safety precautions. The details should be covered in whatever casting training you received, whether online or in a class.

In this instructable, we'll erase the disk by melting it. Hard disks are mostly made of aluminum, which can be recycled, so don't throw it out! Instead, we'll cast a new solid-aluminum hard disk using the original as a pattern. For this project, we'll use the aluminum foundry at TechShop Raleigh-Durham. That way we have all the casting tools we need, including sand, furnace, flasks, and molding tools.

Step 1:

Picture of
The first step in any casting project is to prepare the casting sand. Start by sifting the sand to remove debris and break up clumps. Then add water to temper the sand so that it sticks together. Add enough water to make the sand slightly moist, but not wet. It should clump when you squeeze it in your hands, and break cleanly rather than crumbling when you break it. If you add too much water the sand will get sticky, and stick to both the tools and your pattern, making it difficult to work with. The additional water will also generate more steam, which can interfere with the quality of the casting.
OmnivoreNZ1 year ago

I find 140 Amps from an arc welder makes a nice mess of a drive. Melts and blows holes in the casing and the platters. Of course, it's better to dismantle it and get those nice magnets out.

sreeci3 years ago
Dear God, do we have to do all this, when we do not have time, these days?
I am not trying to be negative. NO never. The best way to discard an old HDD is to open it up, remove the shiny platters (can be used as Sun reflectors) remove the Neodymium powerful magnets and send the Aluminium cast body for recycling. The end.
A fourth grader wanted to do a class report on recycling. With the help of her mother and a camera, she followed the recycle truck that picked up the separated paper, glass, plastic and metal from the school bins. They followed it to the waste disposal facility where the truck dumped it with all the other garbage. Recycling is typical government program..........all feelie good and no action.
Recycling isn't just a government program. It's many government programs, which vary from state to state, county to county, and even town to town.

Yes, there are some fake recycling programs where no actual recycling happens, and all your work of setting recyclables separate from trash is ignored, and it all goes into a landfill.

At the other extreme, there are recycling programs where the resident throws everything in one bin, and it's sent to a facility which separates everything, with metals, glass, plastics, paper, etc, each going to separate destinations... and little or none of it going to a landfill.
Orngrimm sreeci3 years ago
You are right, but that wouldn't be 1% of the fun, right? ;)

However, the neodynum-Magnets from HDDs ARE a nice thing to have for all kinds of things.
There are a lot of cool instructables who involve magnets. Here you have a free source of really powerfull ones. :)
If one strikes a hard drive above the read/write head assembly, the head assembly will be bent out of place and the data on the platters becomes completely useless.

Why? Because the platters are calibrated to the read/write heads during a low-level format that's generally done at the factory. This format becomes a type of fingerprint, making the pairing unique (not to be confused with an operating system format (which lays down the O/S specific file system). If one were to transfer the platters from one hard drive housing to another, or replace the read/write head assembly, they could have fun doing a low-level format (given the proper utility). Attempting to read old data off the new platter/head pairing would be like trying to decode the static that radio telescopes receive.

Contact Seagate. They make the stuff. And they'll tell you the same thing.
I worked as investigation engineer with LaCie for some time and believe ME:
If the platters as it arent physically destroyed and the metallic structure of the platters isnt physically rearranges (like with melting & grinding) you ALWAYS can get to the data.
It may take an electron-tunneling-microscope (to generate an optical representation of the magnetical topography) of all platters which is EXTREMELY costly (we talk in the 100'000s of $). Later you can then rebuild the complete data using this magnetical topography even if you only have the platters without the pickups.
However, if you have the platters in good condition, you can reinsert new pickups and do whats called a sequential sweep:
You go trough all possible adjustments of the pickups (normally around 1-10 mio) and read a known portion of the disk. Every disk has this. And if it at least the preload of the TOC and MBR. Those few bytes are ALWAYS known regardless of the format of the Data itself. Now you just look for a configuration-set which yield those known bytes from the known location. If you have those, you make a complete read of the platters as Raw-Data. Then you analyze the data and decide if that was the correct adjustment for the pickups or not. If not, you look for the next configuration which gives you the correct preload-bytes.
This "look for conf to get correct preload and make a Raw-read" is often automatic and you end up with maybe 100 Raw-dumps to wade trough...
Cheaper than the tunneling-microscope. ;)

And in a nutshell: Ripping and destroying the configuration of (or the pickups itself) does NOT make the data unreadable. Thats an urban myth. It simply makes it harder (Laborwhise and moneywhise) to read the data.
Haus Page2 years ago
Sweet, can't wait for the owl demo.
w0ot!3 years ago
Hey nice instructable on sand casting! Do you really melt your metals inside? For all those readers and commenters who think this is the best way to delete the info on a hard drive, and those who mention the many ways one can destroy a hard drive, another way to "recycle" a hard drive is to wipe off the data and reuse it.

I use http://www.dban.org/ to accomplish the job. It's free and removes everything.
jgregory833 years ago
I find mixing up a batch of thermite works really well also. Not to mention its cheap.
My first thought exactly.
Apex3 years ago
I found a 12 ga or .40 cal works wonders on making the data inaccessible. Just a thought
actimm Apex3 years ago
Well, sort of. There is actually a technique that involves using a really high resolution camera (think microscopic camera) for physically reading the data off the disk. It takes a long time, but except for the areas actually damaged by the pellets or bullet, that data can still be read.
Apex actimm3 years ago
The actual area damaged is relative to the amount and type of ammunition you use
NungaBIZ3 years ago
Um, great casting Instructable not so great HDD disposable one. If you placed this one in its appropriate place with an appropriate title we would get more out of it; just a thought.....
After thought,; whats the BEST way do trash all drive data? Depends on what you have at hand. A small thermonuclear weapon with its casing removed from the primary would create an E.M.P. that would trash its data for sure....... just another thought...
Orngrimm3 years ago
Hahaha! How cool is that!

So you have to strip the harddisk from the PCB and motor first?
At least the motor has a lot of another metal in it, right? Doesnt this make some sort of Copper-Aluminum-Iron-Alloy then afterwards??
evanbd (author)  Orngrimm3 years ago
There are a bunch of metals involved. The cover (not case) is stainless; it doesn't melt, and was basically intact when I pulled it out of the crucible before pouring. Some of the motor pieces were also steel / stainless, and survived as recognizable components. The PCB and many of the chips survived in recognizable (though far from usable) form.

Steel and stainless survive unscathed (you can make hot metal tools out of them). Lead will dissolve in trace amounts, but there probably wasn't any lead here - modern solder is lead free. I don't know what the tin does, but almost anything that melts will dissolve at that low a concentration.

Copper in the wiring won't melt, since the aluminum is below the melting point of copper. However, the aluminum dissolves the copper, similar to water dissolving eg salt. I didn't find any copper pieces after the pour. The same goes for the rare earth magnets; they seem to have dissolved as well.

And yes, this makes this some alloy of unknown composition, but that's what it would be anyway. Copper, zinc, magnesium, and silicon are all common alloying agents in aluminum. There was certainly some zinc and magnesium in this pour, based on what I know was included in the scrap. Probably some silicon; copper was possible. Also, the steel crucible adds trace iron contamination. Iron is not a useful alloying agent, but also doesn't hurt much at the typical trace level.
I'll run right out tomorrow and buy a furnace and melt mine.
Notbob Orngrimm3 years ago
Stripping out the motor and the PCB would be advisable, but not 100% necessary.

I'm no expert, but to my understanding:
Of all the metals commonly found in a HDD, the aluminum and lead will have the lowest melting points, with copper/iron/the others being notably higher. Assuming you don't run the foundry too hot, you should be able to melt the aluminum (and lead) out, and be left with the other components in a solid form (the PCB and some of its components will burn up though). The lead and aluminum should be easy to separate, as they have different densities and one will float on the other. (fun fact; steel floats on molten copper)

Assuming you do run your furnace hot enough to melt everything (and burn off that which does not melt), separating out the different metals shouldn't be too difficult as, once again, they have different densities, so they should naturally want to separate out. (like oil on water)
golfchef3 years ago
Well, if this is for an old, obsolete hard drive, what I've done is remove it from the pc, put it on a rock in the back yard and belt it 3 or 4 times with a 5 lb maul. This seems to turn it into a chunk of scrap metal which I then drop off at my communities recycling center.
bpfh golfchef3 years ago
At an Alcatel site I used to work at, the hard disks were destroyed either this way, or by flagging down a friendly construction worker who drove his road compactor over them, changing them to omlette à la hard-drive...
EdRothe3 years ago
I beat my old HDs with a maul (heavy hammer) until it wont run. I thought that was secure. Can anyone tell me it isn't?
no it is not secure. chances are all you did was destroy the pcb and/or the connections. the data is stored on the magnetic plate on the inside, and they are VERY well protected from sock. (not that you should smash your HDD the plates may survive but other important mech is not.) all someone needs to do is replace the broken parts and volla working hdd filled with sensitive data. did it once, not easy but VERY possible.
Hard drives protected from socks? BRILLIANT! ;)
Not *my* socks.
They would need A LOT of protection from my socks. Heck, some days, the whole computer runs and hides from my socks as soon as I take my shoes off.
*shock :P
no coffee today
cfuse EdRothe3 years ago
Data recovery companies are able to get data from drives that have seen far worse.
It isn't................
Lee Sanders3 years ago
That is the way I want to go. Just to watch it though as I do not store anything on my computer that I really care about except old pics and my instructables password.
timlh3 years ago
Casting ible is great. For data security, encrypt the drive before use and scrub it with one of the utilities afterwards, and you'll be OK
Kinnishian3 years ago
This is actually just an instruct-able about casting. A lovely one at that, hiding the information between the more interesting guise of "recycling the harddrive." Everyone knows it's reuse before recycle anyway, and that Alu melting takes a ton of energy.

Didn't think that alert was necessary until I read the first several comments below :p. I was going to just leave it at something to the likes of "thanks! Cool instructable."
t.rohner3 years ago
Nice idea

A power drill or a sledge hammer does the job faster.
martinex3 years ago
We use a degausser at work. If you don't have access, a strong magnet should do the trick.
jim_lewis13 years ago
It¨'s a bit old now, but this story caused some concern at the time. Given the regularity with which companies/government agencies lose data perhaps there's nothing to be done about data they hold on you, but your own private data should still be protected.

beth.a.mck3 years ago
I took a hatchet and a maul to mine. It was very satisfying!
Arty Marty3 years ago
Firstly I love the instructable, and I love casting.
I make small sculptures and jewellery etc...
EvanBD is totally on the money about the level of moisture needed in the sand to be correct... The finer the sand and level of detail you want, the more critical the water level is.
....to the point that some days you wish you had just stayed in bed because you keep getting deformed results. :o)

I have included a photo of one of my castings, and no bits and bytes were hurt in the process. There was a small amount of swearing during the process though. haha

On the data side of things, which to be honest, that is NOT what this instructable is about - get a grip people!! It's about casting...

But anyhow...
I know that you can get data back from multiple erased disks etc... so I am not arguing with that.
Standard "Department of Defence- DOD" practice is to multiple erase with random data, grind disc platter down to a fine powder and then mix in with cement for foundations of the next building.
All that aside, from my previous 15 years of experience in the tech industry, it amuses me to no end, the amount of paranoia and self importance people have.
The paranoia level is usually way too high, and that is perfectly matched with a level of self importance that is way higher than it should be.

Yeah, I am sure someone is going to want to employ DOD level of hard drive forensics because they want to find out what you wrote on your English assignment 20 years ago that just happens to be on your hard drive to this day.
Have you thought about the fact that it would be many times easier for some criminal to put a sack over your head, throw you in the back of a van in the morning as you walk out your front door, clip off your little finger with a pair of bolt cutters and then say, "Tell me your bank details, credit card info and passwords or we start working our way up in finger size". The whole process would take around 10 min and reveal a lot more valuable information.

Also try not to sacrifice the environment with waste and chemicals for the need to destroy that year 11 English assignment in a subdirectory on your harddrive...
oppie3 years ago
ccleaner has a drive wiper utility with multiple levels of thoroughness - from single to 35 pass overwrite. They used to call this DOD rated but have since changed that name. Sounds to me like this should be unrecoverable. Simple but not nearly as satisfying as a sledge hammer or heating it past it's currie temperature. Comments appreciated
suayres3 years ago
Or, if you have any friends who work with MRIs, have them run it through--it'll wipe that hard drive clean as a whistle. My hub used to work for a manufacturer of MRIs, and he and his friends decided to try a little experiment, with the aforementioned results. BTW, don't ever leave credit cards or other materials which can be negatively impacted by a magnetic field, anywhere near one.... Or you'll have a bit of an "oops" on your hands.
Don't put anything of a personal or sensitive nature on your computer to begin with ( keep it on a flash drive )
I would just like to add this link to everything


I would like to point out this hard drive fell from freaking space and they still were able to get 99% of the data off it.
Thus short of completely destroying the entire disk data with always be recoverable regardless of what BS software you want to use.
It does not matter if you run 1 wipe or 900 wipes if you have enough time and money you can get the data.
Time and money being the key point here.No one gives a damn about your crap data.No one cares that you banked on your computer.If you run just a simple program like Kill Disk 1 time your fine.If your worried about your data that much take a part the whole thing and break it with a normal hammer. Problem solved.
In conclusion no software can EVER FULLY remove any chances of data recovery.Can it make it so unlikely as to be pointless ?Yes does anyone care enough to even try to recover your worthless data ? NO.
when we retire a computer at work we take a drill press and make many holes in the hard drive. I'm guessing this method is sufficient... any thoughts? nevertheless, a very cool and interesting instructable. thanks for sharing it with us! :)
theoretically there is still residual magnetism in any sector that the drill press didn't hit that *could* still be readable, i say sandpaper or melting are the best tactics more complete destruction. remember is isn't about how much damage, it is about where the damage is.
that makes sense. thanks for the response.
Tspherix3 years ago
I think the 'Securely erasing a hard disk' title of this 'structable is partly for amusement. This mold idea is awesome- and you do happen to destroy your disk securely in the process. A+!
ozmont3 years ago
Used to ose a hammer and all and if you are really worried about it there are companies that shred drives physically like this one http://www.datadev.com/hard-drive-shredder.html
There are also smaller ones that automatically punch large diameter holes in the drive. My low tech soluton is a 6 foot concrete breaking spike which will make short work of any platter! :)
mack_jigger3 years ago
Can someone tell me if this is true: If you format (note I didn't say quickformat) a NTFS formatted hdd to FAT32 and re-format to NTFS, it really erases the hdd completly?

I'm not trolling, I just don't know the answer and I'm curious.

TIA ;-)
Do remember a case a few years ago that had the forensic guys all ticked off because an accussed fomatted his drive with Linux EXT3 format and they couldnt get any data off it, but I wouldnt swear by it. As the FAT32 and NTFS, I have recoverred data from that.
Data can still be recovered, formatting does a simple one pass overwrite. so it only actually damages so many files. if you want to erase a hdd (or even empty space on a hdd without losing ALL your data) use ccleaner it has a multi pass overwrite. if you data is "uber" sensitive (or illegal but i am *not* condoning that, simply giving knowledge) they run a 5 pass overwrite as many times as you have patience for. (it will always technically be possible to recover data but every time you run a complex over write it gets harder) another method is a strong magnet or completely destroying the data disks (they must be REMOVED from the HDD, simply smashing it will not damage the disks unless you use a car compactor or several .45 caliber rounds.) i recommend sand paper a magnet AND snapping/bending, as you can NEVER guarantee that every last bit of magnetic charge is unreadable. but "un-formatting" a disk can be done easily by anyone with a brain by using free software and Google. (but the number of people with brains these days seems to be decreasing, so you SHOULD be safe)
Technically, it will erase the hard drive, but data may still be recoverable. My understanding is that the full formatting just writes 0s over the drive, so you'd effectively be doing a two-pass wipe with 0s. I don't know that any consumer software would be able to recover your data, but I'm definitely not an expert!

The DoD 5220.22-M spec is to write random 1s and 0s to every sector of the drive seven times, which does a decent job of making the data unrecoverable. The current spec for drives that have held classified information doesn't allow for anything other than degaussing and destruction of the media, though.

Remag12343 years ago
WOW, I thought there was only 1 James Bond who had Top Secret information. It appears that most of you are James Bond incarnate or wannabes. As stated in several posts, drill some holes and be done with.
This instructable is Overkill in every sense of the word. I guess the author has too much time on his hands.
Again WOW!
smalcolm3 years ago
Instead of going through all that, just drill a couple of holes through the platters.
It's quick and doesn't involve sand.
cfs_pm3 years ago
EdRothe is right. The quickest way to make the data unrecoverable, that you can easily do yourself, is to put the drive on a concrete floor and hammer it real hard a few times. If you're extra paranoid, hammer a big nail all the way through it a few times, too. At that point, if you had a few million dollars to spend, the right people might be able to eventually recover some of the data, but my guess is that most people's data is just too boring to justify such an expense.
otherr than the nail, or a lucky hit. it is still not that difficult or expensive to recover. unless the plates are destroyed other components can be replaced fairly easily. (well easily compared to similar virtual dumpster diving techniques) a paper shredder will not make it impossible to piece together sensitive files and destroying a hdd has the same principals, unless you change it into something entirely different (ie. melting, burning or many many many overwrite cycles) it will always be possible (even if EXTREMELY difficult or even impossible with today's technology) to recover. it would take under 100 bucks to find replacement parts.
mtoddh3 years ago
Just drill a 1/4" (4mm) hole through the entire unit, offset about 2" (50mm) from center.
dalesql3 years ago
When I needed to do secure data destruction on hard disks was to dismantle the drives and recycle the various other components, saving only the magnets and the platters.

the platters got a date written on them with a sharpie, and I used the magnets to stick them to the side of a steel file cabinet next to the phone in the computer room. Whenever I was on hold with tech support, i would rearrange the magnets on the disks on filing cabinet. After a few months of this treatment. (that's why I wrote the date on the platters) I would take the data platters to the rifle range and using some string, hang then platters from the target frames. Then shoot at them, and encourage all the other shooters that happen to be there to shoot at them. End result, a twisted perforated piece of metal that goes into the metal recycling bin.

At my current job, we have a sandblasting cabinet. I'm considering sandblasting the oxide layer off the disks as an alternative.
I love your method! Sounds like great fun. I do the same thing on a smaller scale for CD's with a slingshot! There's a youtube video called 'Proper CD Data Encryption Technique'. Erasing data should always be fun!
This works well too:


As does this:

webshinra3 years ago
Hum, it's fun, but far less efficient than using shred.

(man shred:
SHRED(1) User Commands SHRED(1)

shred - overwrite a file to hide its contents, and optionally
delete it

shred [OPTION]... FILE...

Overwrite the specified FILE(s) repeatedly, in order to make
it harder for even very expensive hardware probing to recover
the data. )

(it's a standard GNU/Linux command)
thegrendel3 years ago
A simple way to "destroy" an old hard drive is to:

1) Disassemble it.
2) Remove and save the magnet, which can be reused for projects.
3) Remove the drive platters.
4) Physically abrade the surface of the drive platters with
sandpaper, emery cloth, or a rotary sander.
5) Break apart the logic board with pliers.
6) Recycle all the scrap metal.

Even a forensic lab wouldn't be able to recover any useful data.
Just adding a step 4.5: cut the platters into at least 4 pieces and dispose of these pieces in separate trash containers, preferably in multiple cities and/or counties that use different trash services. If you're really paranoid (like Mafia destroying evidence paranoid) that is.
A service that would probably be a big hit is to offer hard drive destruction where you pour the melted hard drive in a "Hans Solo in Carbonite" mold and give it back to them :)
csiegl3 years ago
Only the platters containing the data need to be destroyed sand melting them down is a very effective way of doing this. However many of the components of a hard disk drive are not aluminum and would best be removed before the melt down - they just make for lots of toxic smoke and left over material you do not really want in your casting.

The electronics printed circuit boards should be removed, the FR4 epoxy fiberglass board material is designed not to burn easily and is toxic under high temperature. There is also usually two rare earth magnets which can be put to interesting uses, as well as bearings and a spindle motor and other interesting mechanical parts, plus screws which usually require special bits - Techshop has these on the shelf.

So remember only the platters (round disks) need to be destroyed that is where the data is stored. The frame of the disk drive is usually a aluminum alloy and can be melted down, but all the rest of the drive can be put to better uses, just put them on the binwall at Techshop.

Happy Casting!!!
mack_jigger3 years ago
@evanbd: I gave you 4.5* for one single reason: you actually did this for real and I think it's awesome and cool instructable
lkrze3 years ago
I have a super magnet that will lift 880 lbs. (Magnet weighs 9 lbs). Sort of quick erase. Works great, but NOT RECOMMENDED.
I type more slowly now, after carrying the magnet too near a metal pipe. Small finger on right hand broke and is permanently bent at the end joint toward my thumb. (This occurred while demonstrating the dangers of super magnets to my research class. I felt more stupid than pain - until the next day when the pain kicked it.)
If you can find it, a bulk VHS eraser does the job quickly and completely (and safely).
Yes, I realize that the topic isn't data security - its all in fun... Unfortunately - the finger story is true...
cllaudia B3 years ago
you can always send to me you old hard disk, i make some jewelry.
You can see what i create with them on my facebook, claudia Bijoutia. fiorentino.
After i used it no need to protect it! ahahahahhaah
have a good day!
i can also make a necklace for you with your old hard disk

claudia B, bijoutia, e-artiste
hungyhipo 23 years ago
im not quite sure what you are getting at. is this just a joke because it seems to make no sense
whats not to understand? he erased all the data on the HDD by melting it down
he then proceeds to pour it into a mold, so its recycling in a way

the instructable is more about making a look-a-like HDD from aluminium, its not as much about the "erasing data" part :P (thats just 1 sentence: melt the sucker down!)
ok, i didnt read all of it because it didnt seem like it was what i thought it to be. if i took the time it would have been funny
No offence, but I hate people like you for that. Why would you post a comment asking about the instructable before taking the time to read the damn thing? It's rude and is a disrespect to the hard work put into the planning, execution, and publication of the project. If you're not going to spend the time to read it, don't post here. Go back to funnyjunk or wherever the hell you came from.
Well i was short on time so i read the first few in depth and skimmed over the melting part hoping that id find something quickly. It was just so far off from what i expected that i wasnt sure what was going on.
deadsy3 years ago
I've used this secure erase methodology on a few HDD's myself. The case and platters are typically Al, but everything else is generally non-Al. It's probably an idea to strip that stuff out before you put the good stuff in the crucible. ie- try not to get cancer from breathing in the fumes from burning that crap.
code_neon3 years ago
Why do it the simple way, when you could do it the TechShop way!

Very cool!
Tkdwn3 years ago
Tnx! Looks grate.
nmachado43 years ago
este trabalho deveria estar no facebook. ridiculo
Haha This should be called "How to turn your hdd into a Hon "Solo" disk drive." VERY coool instructable thanks!