Jack,
Your "12,000 rpm test to destruction" reminds me of a story told to me by Duane Korn, former owner of H&L Metals in Signal Hill, Ca. (H&L was the go to place to have tubing bent in So Cal for years) Duane was one of the original members of SEMA, which at that time stood for "Speed Equipment Manufactures Assoc." and one of the SEMA members made racing flywheels and clutches ,don't remember the companies name, anyway he decided to make a test cell in which he was going to spin one of his flywheels up until it exploded. Duane said the guy built a big steel box from 1/2 inch plate, fully welded all around with a 1/2 plate door that allowed you to mount the flywheel to a shaft that was spun by an electric motor with gearing that would make it go to 10,000 rpm+. The door had heavy steel hinges and was bolted closed with 1/2 inch bolts. Well they had the initial testing and most of the SEMA members were there to watch the "blast". The guy starts the thing up and he starts to ramp up the speed and Duane said he started to move to the very back part of the room! When it blew up at around 10,000 the box turned into a "ball" and the door was almost blown off! So be careful!!!
Rex