To give you a better idea, I have it drawn out here: http://tinypic.com/r/eq6ln5/6 I am calling the thickness of a rod t and the thickness of the shaft t2. I am using the basic equation Ixx = (integrate over area)(y^2)dA on different sections and then adding them all together, following the guidelines of this website: http://www.brighthubengineering.com...-inertia-of-irregular-sections-in-five-steps/ I split the shaft into sections, as follows: http://tinypic.com/r/2j5mc8l/6 I calculated the moment of inertia of each section and added them together. Referring to half of one rod (aka half of the inner diameter) as L, I have come up with this equation: =2*L^3*(SQRT(2)/2)^3 (three rods) +2*(t*L*(1-(SQRT(2)/2))) (top of center rod) +L*t^3/12 (middle horizontal rod) +(PI()/4)*((L+t2)^4-(L)^4) (hollow cylinder) Am I going about this the correct way? Any suggestions would be appreciated. Thank you!