The table top is about 40 years old and was made out of walnut boards that had been in the loft of a barn for 10 years. (I assume well dried). The top is 3/4 inch thick but the builder put a collar on the underside of the top that is 34 inch thick and 4 inch wide. It was glued and nailed. Each of the 4 rails had 12" long glue blocks that were glued to both the rails and the table top. Obviously, no allowance for wood movement. A repair was attempted, the glue blocks removed and replaced by 4 strips of angle iron placed underneath with screws every 2 inches. The angle iron was screwed to the rails and table top with no allowance for movement. The cracks are all the way through the top and run the full way across the top. All the original glue joints on the top are in tact. My plan is to remove the iron and screws, try to ease the collar glue joints with heat and water, remove the rails, clean the cracks, re-glue with titebond II. Obviously the rails will need to be reattached to allow for move movement. Unsure though whether to add dutchman's across all cracks or should glue be sufficient? Any thoughts on this would be appreciated.