Gentlemen, I am about to start a dining room table for a friend and it will be constructed from poplar, which I will end up staining. Top will be between 1 1/2" and 1 3/4" thick. It will have breadboard ends and will be six foot long and roughly around 42 inches wide with various width boards composing the tops field. The individual boards will be joined using glue and splines. I am concerned about the expansion and contraction of the tops field in relation to the length of the breadboard ends. I know poplar is one of the more stable species, but I am in the dark as to how to relate the breadboard ends width to the possible reaction of the top field to the moisture variations from season to season. I have never worked with the expansion and contraction calculators on line and took a look this morning at them, but feel a bit intimidated by the process. Someone want to take on the challenge of explaining how these calculators work? I am a bit naive as to starting moisture content...final moisture content, etc that are the needed figures in calculating the growth or shrinkage of a chosen species of wood.