Just out of sheer curiosity, I was wondering if microwaving a hard drive will actually make any data on it unrecoverable by all standards. If this is not, is there any other way that is not software based?
I would think the metal case would sheild it from the microwaves.
What if I was to open it up and expose the platters?
There is only one other way. 
I’m thinking sledgehammer.
If you are going to go that far, just break the platters with a screwdriver and a hammer. That is the end of that.
Are you trying to destroy a microwave as well?
I know a company that is in the field of data destruction. When they are done with the disk it is just clear, no silver left on it at all, that is all powder. I’ll put a link if I can find one.
Are the feds knocking?
No. Might damage the interior cavity finish due to arcing, but the magnetrons are a lot tougher now than they used be. Heating due to reflected energy is of little concern anymore. You can run a modern oven for a long time, even empty, with no damage to the tube.
If so, his posting on the Dope indicates that he forgot the all-important first step: take the hard drive out of the computer.
(The whole computer probably won’t fit in a microwave, at least if it’s a desktop computer.
I’m thinking industrial wood-chipper.
I would think a Master Thief should have access to a blow torch.
I work at a company that regularly has to destroy HDs to comply with government requirements for security. We just run a spike through the drive with a 22 oz hammer. Its easy enough that my 5’ 2" 105 lbs wife was able to do it each time on the first hit. The disks just shatter in the case. Maybe the feds could pull data from the broken disks if they really wanted to but barring a major crime on your part this should insure no one is going to read the data.
I used to know a guy who was concerned that his hard drive would fall into the wrong hands. He was not entirely on the right side of the law, and he was a conspiracy nutjob as well.
His answer involved a powerful electromagnet that he could “turn on” using a remote control device. Like I said, he was/is a nutjob.
Shotgun.
He’d have been very surprised when his computer booted up afterwards and spilled all his information. You’d need one HELL of a magnet. The flux density between the head and the platter is pretty high, but they’re only a few microns apart. A magnet external to the drive casing is thousands of times farther away from the platter surfaces than that, and the field strength drops off as the cube of the distance. I can’t seen a conventional electromagnet powerful enough being sufficiently small to even fit inside the PCs case.
His surprise woulda been behind bars, as well. He had a touchpad that he installed in his coat closet. Upon entering the house, a password had to be punched in or else the magnet would activate. Like I said, a nutjob.