Quote:
Originally Posted by VanceHanna
Both? I didnt know there was such a thing as a secondary bevel. I thought you set your angle and sharpened.
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With a 'scandi' grind, there is only one bevel, usually set to around 12 degrees inclusive... with a convex 'appleseed' grind, there is no bevel at all, only 2 curves meeting in an edge... with most modern knives, you have a primary bevel that is largely dependent on the width and thickness of the blade, and a secondary bevel which actually forms the edge. To make things even more confusing, the Japanese call the secondary bevel the primary bevel...
Think of it this way. If you have a typical flat ground knife, with the primary bevel going from the spine all the way to the edge, you will have a blade that will cut like a scalpel, but if it encounters resistance the edge is fragile and will likely fold or chip. There are two ways to deal with this, you can either make the primary bevel steeper (scandi grind), or you can add a secondary bevel.... or you could do both (saber grind).
For a knifemaker, the primary bevel is ground before heat-treating, and maybe thinned a bit afterwards as the blade is polished. The secondary bevel is applied last, after everything else is finished, as it is what makes the knife sharp and we don't want to be bleeding all over the place... the cutting ability of the blade is dependent upon the angle of the secondary bevel, the amount of force needed to make the cut is also dependent upon the thickness of the edge and the acuteness of the primary bevel.
I like a very thin edge, with a secondary bevel around 15-18 degrees per side, unless I know that the knife will be used roughly for chopping wood or bone, in those cases I'll leave the edge thicker with a less acute secondary bevel.