If you put a perfectly balanced prop on a balancer and touch it so it rotates, it should coast to a stop, without bobbing back and forth, at completely random places. Don't find one that's perfect very often. If it always lands horizontal, with the same side down, the prop is heavy across the hub. Sometimes you can shave a little off the hub and fix it, but I won't take very much off, for obvious reasons. I use an older version of this balancer with the wheels instead of the magnets to support the prop. It will also do spinners, boat props and heli- rotors.