This is a bad method to try unless you really know what you are doing, breaking a platter up only destroys data where the fracture lines are, it can still be put back together and read with spin stand microscopy. I don't know if it will work for bent platters but it certainly will for shattered platters (that is one of the things it is primarily used for, reading data off shattered drive platters). I wouldn't trust bending much either as it doesn't actually destroy any data and only is a physical limitation attempting to prevent forensic tools from reading the data that is still there. Grinding to microscopic bits will leave data behind as well, but it would probably be infeasible although not impossible to perform spin stand microscopy on a platter broken into hundreds of thousands of bits, since it needs to be pieced back together. But there are drive internal programs (firmware) that can do this, namely Secure Erase. Some of the newest generation SSD's have automatic passwordless encryption that seems to exist for the sole purpose of allowing you to Secure Erase by wiping a random key stored in a protected erasable area. Obviously the people who made Secure Erase thought the track edges could have data recovered from them, since it uses an off center wipe as well. I did read research showing that they were incapable of pulling data off track edges though. As for the comment that spin stand microscopy no longer works, well that is news to me. Personally I will tend toward the side of caution and not try to destroy data by smashing my drive platter (as historically this has not worked), nor by bending my platter (as this doesn't actually destroy data just makes it hard to access), and rather will stick with what I currently do, which is Secure Erase followed by a single pass of random data with something like DBAN.