shaping the rails

anyone there guys,what’s the easiest way to shape the top rails when doing mid or low or boxy,what exactly would be the measurements to shape them.

I learned through JC ,I make a 2 and 4 inch marks @ center and 16 inches of the tail

and 1 1/4 marks from the bottom of the board @ the same distance.

I guess that will give me a pretty standard rail,but it changes when the board is thicker or thinner.

any feedback would help,thanks

Maybe your problem is that you are trying to apply advanced mathmatics.

Instead, picture your rail shape in your hands, then run your hands over the rails while holding the blank over your head, and slide your hands towards the rails.

If you can’t picture that, lay the board on it’s belly, on a stand, and run your hands along the rail. Picture the shape you want to achieve.

For me, shaping is feel. For others…