I started on the X axis cross slide. I ordered some precision ground flat stock. It was +-.0001". After I cut it, it curled up to where the ends were now .0004" low and the middle was .0004" high. It took me almost 4 hours of scraping to get it back to flat +-.0001". I cut a groove down the center (before I started scraping) with a 5/8" ball end mill to made room for the Acme nut. It did not warp any after the groove which surprised me.