The primary bevel is the angle of grind from the spine (or from a point below the spine) to the secondary bevel. This angle is about 7 degrees, give or take a few. Even Scandinavian grinds have a primary and secondary bevel. This is because they are ground at a slight angle from the spine down about halfway (not all of them of course), then there is a secondary flat grind to the edge. I suppose there could be a few exceptions if there are Scandi grinds out there that are flat-ground from the spine all the way to the edge. In that case, there is only one bevel.

The cutting edge of most knives is found in the secondary bevel, which is usually ground between 12(24) and 20(40) degrees.

A micro-bevel is actually the third bevel. It is ground a few degrees more obtuse than whatever the secondary bevel is ground at. While it's a personal choice, I like micro-bevels. The knife's life doesn;t end when, after repeated sharpening, the secondary bevel becomes more obtuse, because it never does if the knife is sharpened properly. When sharpening, the secondary bevel needs to be ground at each sharpening before finishing with the micro-bevel. So..... how could repeated sharpenings make the edge more obtuse than with or without a micro-bevel?? THink about this now. You have a 7degree primary bevel on a flat-ground blade. You grind the secondary bevel at, say, 15 degrees. Each time you sharpen, you keep grinding that bevel at 15 degrees, whether you grind a micro-bevel or not is irrelevant. At what point does 15 degrees get more obtuse than 15 degrees? Do you think you might hit the spine someday? I don;t.

The Edge Pro is a great device...I've seen my neighbor use his. It also costs a fortune. Ors has a Sharpmaker...it's like a bird-in-hand. It will sharpen ANY knife (except a ceramic blade) that he wants to sharpen. Don;t give up on it Ors, IT WILL SHARPEN your RSK.