Primary/Secondary Bevel Discrepancy
The 'Primary/Secondary' Discrepancy
There is a divide in the accepted nomenclature denoting the order of bevels. The terms 'Primary Bevel' and 'Secondary Bevel' are often used to mean exactly the opposite thing, depending on who you ask.
The order of bevels, as accepted by the woodworking, metalworking, and engineering trades, counts bevels in order of their deviation from the original flat plane that is altered to make a bevel(a bevel being simply any slope added to an item). So the first bevel cut into a knife is the Primary, the subsequent, wider angles, are 'Secondary', 'Tertiary', and so on, and the bevel that makes up the cutting edge can be any of these bevels. The face is not considered a bevel, as it is the plane that is being altered.
For whatever reason, either through historical convention, or logical re-evaluation, the names of bevels in the knife world are often reversed. The Primary Bevel is always the cutting edge, and the subsequent, narrower angled bevels are 'Secondary', 'Tertiary' and so on. This is likely because the cutting edge is of utmost importance in knives, and receives the most attention.
While the first usage is more widely used throughout different trades, the second usage is supported by a large section of the cutlery world, and promoted by some of the most well-known and respected members of the knife sharpening elite. Due to the widespread implementation of the second method in the knife world, neither method is wrong(usage determines meaning, eventually), but due to the fact that there is never a clear cut consensus on which is “correct”, and the first usage being constantly imported from other trades, this is not likely a debate rested any time soon.
I guess we just have to agree to use one or the other...and this is Dave's forum...and he goes with convention (2)...
I like Eamon's explanation, it states that neither is wrong and the reasons why, that works for me.
I switched the Glossary definitions to the second one, not only because that's how Dave does it, but because the purpose of the Glossary was to provide insight into knife-specific lingo, and that way is very common in the knife world. If the first usage wasn't constantly being brought in from other disciplines, the second would be the only 'correct' way, even if some find it counter-intuitive.
Originally Posted by tk59
Remember also that a blade can have only a primary bevel, like a chisel or scandi ground knife or a traditionally polished Japanese sword.
Japanese knife design is it's own bag of worms, and I defer to my Japanese-speaking colleagues for that stuff. Confuses me, and it appears to me that the Japanese themselves don't spend as much time on the science and lingo of it as Americans do.
If it has only one bevel, the fact that it is the "primary bevel" is a priori knowledge. So you aren't wrong.
I have always considered the "face" or that portion of the face which is ground to be the "primary" bevel as it is the first one that deviates from your theoretical squared bar of steel. Other knife makers would probably think the same thing.