Before attaching the ends I needed to drill holes to accept the dowel to pin through the joint. To allow for expansion all tenon pin holes except for the center (which will be glued solid) needs an elongated slot hole. Since the end will always remain stable, and the main table will expand or contract widthwise the unglued dowel pin will ride back and forth within the slot. If we didn’t allow for movement the end could crack away or the table could warp.
