This is a work in progress. I need to balance props for a quad and I'm hoping this will do the trick. I plan on drilling out the hole and taping for a long thin bolt so the cones can be adjusted to the prop. Then balance the bolt on a simple wood frame. Because the surface may not be perfectly level it will be important to flip it back and forth during balancing. 5.15.13 I have reduced the height of the cone. The tips of the cones would touch unless the smallest prop adapter was fitted.