I have watched pileated woodpeckers at work in my back yard. They are formidable.
In one instance, a single pileated woodpecker literally demolished a basswood bolt about 20" in diameter and 24" long one Saturday morning. Basswood is pretty soft stuff, and the chips -- big chips -- really flew, even with the relatively slow cadence of the pecking.
In the woods, pileated woodpecker workings often are large, nearly rectangular (narrower than they are long) vertical excavations on dead or bug infested tree trunks. A good pile of chips will lie on the ground below a fresh project. In some cases, I've also seen a standing dead tree in which the upper part has broken off literally torn apart -- starting at the top and working down -- by the birds. They can produce a startlingly shredded mess.
G.