So I rigged my dial indicator to check my stones. Graduated to .0005" , I observed no movement of the dial at all on my Arkies. When checking my recalcitrant purple slate, I found a gradual .004" dip towards the center. Question is will .004" affect anything while honing? Is there a number, a dimension, that indicates I should go back to the lap? Most folks use a straight edge and look for light, doesn't seem to work well for me. I'm a tool maker and always checking for flat or square at work and shun visual methods do to my eyes.