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.
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.
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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.
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I use http://www.dban.org/ to accomplish the job. It's free and removes everything.
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.
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. :)
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.
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.
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.
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??
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'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)
no coffee today
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."
A power drill or a sledge hammer does the job faster.
http://news.bbc.co.uk/2/hi/programmes/real_story/4791167.stm
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...
:o)
Marty