I finally have my GRS system up and running and my gravers sharpened. I've been practicing as much as I have time for, and I continue to experience chatter in my engraving. Why? The choices I can think of are that my heel isn't right (though I think I'm using all the techniques Sam suggests), my GRS Gravermach AT settings aren't right, or my compressor isn't at the right setting. Anyone have any suggestions on what is causing this? On what settings I should set my system to?