I have posts somewhere a diagram for the power band calculation by using primeline formula and it was wrong as I didn't understand few terms ,I am posting it now after i have calculated according to what I read and learn ,my goal was to estimate the required force minimum and maximum which can apply on 160cm 7mm spring steel shaft and I found out it s enough to load it in range (200-300)Ib ,picture is attached and I like to hear and learn from you guys