Dear all,

I was used I/Dx0.904 (for crown radius) and I/Dx0.173 (for knuckle radius) to draw 2:1Elliptical Head, Some times i used O/D for calculating the Crown and Knuckle Radius (after drawn the Dished end O/D i offset the thickness towards inside of the vessel, for I/D), Sometimes i used I/D for calculating the Crown and knuckle Radius (After drawn the dished End I/D i offset the thickness towards outside of the vessel, for O/D) , I know The D/4 Formula also.
Recently i found there is difference in Dish height when I using I/D and O/D, now i confused which is correct,
please advise me to draw the dished end in correct way and clear the confusion.

Thanks gentleman.