Just received my new 750x Drill Doctor. I have an older DD500, but it won't sharpen anything over 1/2". Now I can get those large bits cutting real good. Have to watch the dvd to learn how this one works. I have been very happy with the old one, just needed one to go to larger bits. This one does 3/32-3/4" bits. To those who don't know about these, they are a godsend to those of us who haven't learned to sharpen their bits on a grinder.