I worked with a guy who decided that it would be a good idea to chuck a 1/8" bit in a Dremel. The motor was set on max speed and when he plugged it in the inertia twisted the aluminum chuck in two, throwing the drill bit. It hit him dead center in an eyeglass lens and poked a hole through it but it stopped the bit. If he hadn't had coke bottle lens prescription glasses he would have lost an eye.