Has anyone tried these? They're all over Ebay and available from Amazon thru Grizzly for about $12-14 (set of three fine, medium, coarse). I'm just looking for a quick, easy, cheap way to keep my chisels sharp while on the job. I've always used a large stone, but it's old and not so flat as it used to be. I've seen these diamond 'stones' for sale, but never tried one.
Thanks