Official Answer
Answer
Wave springs must be piloted to prevent buckling and ensure concentric loading. When piloting in a bore, the spring's outer diameter ($D_{out}$) is the reference. The bore diameter should be sized to accommodate the radial expansion $\Delta D$ during compression, typically $D_{bore} \approx D_{out(max)} + 0.010$ inches. When piloting on a shaft, the inner diameter ($D_{in}$) is the reference. The shaft should be sized as $D_{shaft} \approx D_{in(min)} - 0.010$ inches. In high-speed applications, bore piloting is generally preferred because centrifugal force will push the spring turns outward against the bore wall, providing a stabilizing effect and preventing 'snaking' or harmonic instability.
