Pat, thanks for you comments. The compressibility of the wood is definitely an issue. But I think the thinness of the control surface is being underestimated as a failure accellerant. Just drill the hole a little oversize and you're exposed to failure, hardwood or not. In engineering circles, this is called "wheelbase". The longer the hole (thicker the control surface), the more resistant there is to this pivot movement. Why rely on compression alone for control horn integrity? Eventually, over time, if not sooner, the compression will be degraded enough to allow those ball joints to start slipping. Plainly said, I just would not use these horns on a thin surface without at least substituting flat washers for those ball washers. And yes, use hardwood too.