I am using a bunch of scrap hardrock maple (roughly 1/6" thick) for a bookends project, but the boards generally come quite warped, parallel(?) to the grain. I tried steaming them and clamping them tightly between a flat board/workbench overnight, but they snapped back into shape in less than a day. Besides removing material on a joiner or a sander, is there any way to teach these guys to be flat? #diy