I'm currently milling timbers for a timber frame workshop that I'll be building for myself. Due to the size of the logs available to me I've only been able to mill one timber per log (I boxed the core). However I've just received a load of large logs which will give me the opportunity to mill two to three timbers per log (each will be free of the core). I'm thinking that these will be the best, most stable timbers. Just checking to confirm this before I start cutting. Most of the timbers I'll be using will have the boxed core.
(Sawing and Drying Forum)
From Gene Wengert, forum technical advisor:
The wood within 15 rings of the core (technical term is the pith, although centering the pith in a timber is called "boxing the heart") has a strong tendency to warp lengthwise, but the wood further away does not. So, if the rings are not centered in a timber, the edge closest to the pith is likely to shrink lengthwise and create a warped timber.