Epoxy leveling is used to get the rails on a flat surface and in the same plane. Ussualy only done on welded steel frames which will suffer some distortion due to the heat of welding. Leveling the cuting table is done by skimming the surface with the machine itself. Several build logs have descriptions of the method, some more sucesful than others. I'm sure you'll get plenty of deatiled instructions from those members with experience if and when the time comes.