On 15/04/2021 20:02, SH wrote:
Whenever I wish to sell on of a hard disc, I *always* do a secure
overwrite using a variety of software tools, such as DBAN (Darik's Boot
'n' Nuke)and it gets securely erased to DoD standards..... before it
leaves my hands..... So my personal and financial data does not get
exploited by ne-er do wells....

I had 2 off 40 GB and 2 off 500 GB hard discs that either had the click
of death or was not "present" in the BIOS attached drives autodetection
list.

So Using DBAN was clearly out of the question on any of these 4 drives
and I could't even sell them on for spares or repair as it still had my
digital data on it.

The last time I had to securely destroy a disk, it had glass platters
coated in a magnetic metal oxide.Â* They were *easy* to destroy, with a
lump hammer!

So today I set to work with these 4 failed drives which are 7,200 rpm
versions

Got my battery powered screwdriver and remmoved all the Torx screws
including those under the stickers.

PCBs was successfully removed from all 4 drives and tossed into WEEE bin

The metal Lids was also successfully removed after breaking the hermetic
seal from all four and tossed into WEEE bin.

The torx screws were removed for the read/write heads on swinging arms
and removed..... and tossed into WEEE bin.

Then the spindle annular rings have 6 torx screws, which are
successfully removed and tossed into WEEE bin....

I then remove the platters and I end up with 10 platters (3 form two
drives and 2 from 2 drives)

I then try and smash them with a hammer. just put a dint into the
surface so clearly not glass.

I use mine as beer mats!

This suggests they could be aluminium:
https://en.wikipedia.org/wiki/Hard_disk_drive_platter

I then get the chop saw out with a metal cutting blade... Blunted the
brand new blade.

I then get the HSS drill bit set out and the pillar drill..... The HSS
drilsl won't touch it......

Then I the favoured uk.d-i-y nuclear option... a grinder!

I take the platters to my bench grinder..... the grinding wheels are
blunted and you can see streaks of metal embedded in the discs from the
platters.....

I didn't have a professional grade degausser unit so that was not an
option open to me.....

Given these are written to by heads with relatively low currents, I
would have thought a strong magnet pulled over the disc might be effective.

So I think long and hard about what other methods are open to me to
securely destroy the platters....

My first thought was heat, and most materials have a curie point. I then
looked up cobalt alloy as used on platters and I see it has a curie
temperature of 900C.

I then fill up the garage sink with water after putting the sink plug in.

I use a pair of mole grips to hold the disc platter by the edge and
light my MAPP blowtorch...

I apply the blue flame to platter and then finally manage to melt the
platter and watch molten droplets of metal drop off into the sinkful of
water...

So likely aluminium.

Rinse and repeat 9 more times....

1 empty bottle of MAPP gas later, the metal granules are now in the WEEE
bin!

RESULT!

Well done!