Granite Surface Plates
tony r
>I just received a lapping plate from the Japan Woodworker for flattening my water stones. This thing is only 10 inches or so long and is a bit more than 1/16 concave from one end to the other. (obviously i'm sending it back but i find this astounding that they would sell this product). I also have a piece of float glass i purchased from garrett wade and it too would appear to be out of flat (though in this case its not as bad and could be my starrett ruler which i did purchase second hand on e-bay). In any case, this has all led me to the conclusion that the only way i will ever truly know what is flat and what isn't is to purchase a 12x18 granite surface plate which i can then use to lap my rulers and anything else i need to make flat. Does anyone have any thoughts on what grade surface plate i should purchase for these purposes? Is B enough or should I go for an A? And any suggestions on where to pick one of these up (relatively) inexpensively would be much appreciated. and does anyone have any experience with the grizzly granite lapping plates? they are grade B's and appear to be pretty well priced. thanks much, tony.