Milling PCB's can be greatly simplified and the resolution improved by correct work holding. Simple techniques include double sided tape (Duck brand is good), screws and simple clamps. But to achieve very fine trace width and isolation paths, it requires the surface to be dead flat or a spring loaded cutter head with a depth stop. Since many DIY'ers don't have access or funds for a spring loaded spindle, the need for a flat cutting surface becomes imperative. The problem becomes more complicated when you realize that holding the edges is relatively simple, but what about the interior area. Commercial PCB mills utilize vacuum to hold boards flat across the entire surface area. Here I will explain an alternate method.