I'm fixing up a wooden table that has sat in a warm attic for about 10 years. It's got pretty substantial bow and twist across the planks. I'm a beginner and want some advice on how best to get rid of the warp.
There were three pieces of wood perpendicular to the main planks across the underside holding them together. Before I took them off, I noticed the staples holding them to the planks were partially out, i.e. the warping of the main planks was strong enough to pull them out.
There are also these thin, wavy pieces of metal (what are these called?) hammered across each plank pair (see photo below), holding the them close together. Some of the planks are offset vertically from each other, and hammering hard with a mallet I can't shift these back to being level. The warping has also been strong enough that on one edge the wood around where a wavy metal piece was present has broken under the force of the warp. This has meant the edge plank is no longer flush against its neighbour, and the wavy metal piece is now holding it in a new location. Should I just use a hammer or strong clamp to "crush" this metal piece slightly to make the plank flush again, or must I remove it and reinsert it or replace it?
What I plan to try next, unless someone has better advice, is to replace the staples I removed from the three perpendicular planks with proper screws and drill them in tightly to the underside of the main planks. I hope this will have enough force to undo the bow across the planks. Then attaching the leg structure (left of the first photo) with the same screws I hope the remaining twist will come out. I have not considered using water, steam or other techniques yet - I have no experience with those - but any ideas would be appreciated.
Photo of the whole setup. The three perpendicular planks and staples I removed are visible at the top.