Rob, most folks buy them along with something like a plane or engine. Plus you can slice these plates with your bandsaw into 3/8" wide pieces and use them for 3-4 planes. They provide a nice hard and continuous surface to mount the engines to. Eventually the washers we all used in the past dig into the wood. Go ahead and use the washer technique but you may have to add another to take up the compression over time. Really though it isn't that critical.