I am designing a constant pitch, helical conical compression spring (round wire cross section) that will be compressed into a final desired shape. So my issue at hand is figuring out the pre-compressed geometry that will give me my desired final geometry once compressed. The compression will be accomplished by longitudinal tension lines (fixed at each point on the spring for constant pitch), so the spring should not be torqued at all when compressed. As opposed to keeping the two end orientations fixed when compressing. I have a spring I've been playing with, and my observations are that when the spring is compressed (with no torque), the number of turns decreases and the diameter of each turn increased. I've been unsuccessful so far in finding equations to help me figure this out... Final Shape, Known: Dmin - small diameter, bottom of spring Dmax - large diameter, top of spring N - number of turns h - height L - total arc length, function of other variables, remains constant Uncompressed Shape: Dmin0 - Unknown Dmax0 - Unknown N0 - Unknown h0 - Known, based on the compression I want (~50%) L0 = L Can anyone shed some light on this? I'm not sure if material properties come in to play...I know they will for the compression force required, but I don't know about the geometry. Thanks!