i like my damping (aka o-rings) to be on the tighter side, but the heli can be more forgiving with softer damping. trimming the shaft is an acceptable way of stiffening the damping, or like Heli_Harry said you can also use shims to get similar results. adjusting your damping is not an exact science with cp's, but here's how i do it. i'd say 5-8 degrees of total play for fast flying, and up to 20 degrees of total slop for training/hovering. by "total play" i mean: forcing a blade tip up and down until you feel the wood barely starting to bend.