I haven't updated my profile in a while Horace. I've done a bit more since creating it 7 years ago. To be clear, I wasn't advocating one to use a prop with too big a hole in it, but rather making the point that there is very little sideload on the prop hole, making the debate between straight holes vs. tapered holes or holes a thousandth or two too big moot. As for sharp trailing edges, I've never sanded one off and after probably 1000 engine starts I haven't cut myself once. Even as a newbie trying to start engines without an electric starter I had the good sense not to flip the thing with my bare hand. Anybody that can't figure that out should really consider sticking with video games for amusement.