I never considered using store bought pine for my layout structure. I have seen it move excessively in a matter of hours. I usually refer to pine boards as "crating lumber." The only pine that I will use for any critical project is reclaimed sugar pine.
I have the good fortune of having a large sawmill just a few minutes from our home. I was able to select and purchase kiln dried rough cut poplar for the layout structure. Being that I have a complete woodworking shop, I was able to mill the boards to my specifications. Buying direct from the sawmill is a great way to get good lumber at a reasonable price. Granted, I had to spend my time surfacing the boards. But in the end, I had nice, clear, straight boards to work with. Maybe a little overkill, but I'm happy with the results.
Tom
