I am trying to get my coticule lapped with 220 grit 3m wet/dry sand paper. Most of the stone is flat but the corners on both ends still seem to slope downward.



I have followed the tutorials on lapping marking the surface with a grid and moving the stone in a circular motion. At first, I used 320 grit because it was the closest I could find then I found some 220 at an auto parts store. I have made progress as the corners that were left with pencil marks have gotten smaller. But they are still there!

I have worked on this thing for over three hours total...does this sound right? The corners didn't seem to slope that much to the naked eye (it actually looked nice and flat to my optimistic imagination ).

So my question is, "do I just keep going or is something wrong with my method or my stone?"