Official Answer
Answer
Because wave springs expand in diameter when compressed, the method of piloting (centering) is critical. For 'Shaft Piloting,' the spring's $D_{in}$ is used for alignment. The shaft diameter $D_{shaft}$ should be sized such that $D_{shaft} < D_{in(min)} - \text{Contraction}$. For 'Bore Piloting,' the spring's $D_{out}$ is used. The bore diameter $D_{bore}$ must be $D_{bore} > D_{out(max)} + \text{Expansion}$. Generally, bore piloting is preferred for Crest-to-Crest springs because it allows the spring to expand freely without frictional binding against the shaft, which would otherwise introduce hysteresis into the load-deflection curve.
