You all are forgetting something. Accidents with a prop don't always happen at the field or with the engine mounted on a plane. I had a plane destroyed during a move and built what I thought to be a perfectly usable engine test stand from plywood and wood blocks. Even went so far as to use a pushrod on the throttle to minimize the chance of getting fingers in prop. I learned very quickly that you never trust anything as far as a spinning prop goes. Started the engine after screwing it down and was adjusting the needle when the right side of the plywood failed. The thrust from the MA 9X6 was enough to spin the engine around to the left and the prop got me three times before the engine was stopped by the plywood. I was fortunate that the engine was running just above an idle so I got a total of three cuts to my right middle finger that the wife was able to clean and bandage. I was also fortunate that the engine was an OS 25FP