It’s a no go with the hard drive grinder. I decided to do a few tests before going on with it. It might work with older ESDI or MFM drives from the days of old but with PATA or even SATA will not work for the sheer reason of shock protection. So if you use a medium or heavy grit sand paper the motor will wined down and the motor controller will kick in telling the motor to slow down or stop depending on how hard the shock level is for the motor. You could use fine grit sand paper and use it for sharping razor blades or deburing soft metals. There is some what hope though by using a RC ESC but the strain would might burn it up. There is also another solution I found from here. Just a Shift register and a motor driver with a few discrete parts will suffice. I won’t try it since I already have too many projects going at once. However I will post a guide on what can be salvaged from a hard drive.