I was following the discussion in the Off Topic forum on calculating lengths for sides in an octagon. I have in my list of projects, a round table with a center glass insert. I had been thinking I would make an octagon first then round the outside and inside edges. I anticipate the width of my pieces to be about 4". How do you account for wood movement at the joints between the sides? I see miter joints on frames opening up on frames from seasonal shrink/swell. Am I missing something or is there a better way to do this?