Thanks for the reply I did some more research and found an equation for spring rate of a conical spring. The 8*Dm^3 in the standard rate equation is replaced by 2*(D1^2+D2^2)*(D1+D2). Timoshenko derives it in Strength of Materials Part I Elementary theory and problems. I also belive it is...
thread693-179328
In the above thread it is suggested that the mean diameter of the conical spring be used for a variable pitch conical spring "linear". I have found when I do this the calculated number of active coils is greater than using the iterative process also discussed in the above...
