very quick way to cut and shave down props all the same size
I wouldn't suggest it, but I saw someone shave down a prop while the engine was running using a piece of sandpaper.
It was a Nelson q40 engine, and he held the sandpaper (on a block) up against the prop arc until the prop got small enough to jump on the pipe.
You won't see me doing that at 22,000 rpms.