better than angle grinders
I worked for a DEC house in the late 80s. We had some of these in a room in the middle of the office. We came in one Monday to find that the bearings had gone on one of the disk packs and the platters had gone through the wall and across the office like they were the frisbee versions of angle grinder discs. If it hadn't happened over a weekend there would have been blood on the floor. They put sheet steel round the walls after that.