You guys got me wondering about my LeBlond 13" Regal. It's precision leveled so should not be twisted. To check the bed ways wear I used a length of flat ground stock laid edge down on the ways. Stock showed no bow when checked for flatness on a granite surface plate. Max wear was .002 about 6" from the chuck by feeler gauge. .002 gauge lite drag, .0025 gauge was tight. Simple check and way close enough for what I do................Bob