Primary vs Secondary

[Stacy E. Apelt - Bladesmith]

I have noticed that the term for the knife blade bevels is different depending on where you are.
Since we have people from all parts of the planet here, what do you folks call them?

The bevel at the edge...where the cutting occurs... is commonly called the primary bevel in Japanese terminology, because it is the primary one doing the work. ( it is also primary, because it is the first angle on the blade).
The main flat bevel is called the primary bevel in Western culture, because it is the one you shape first.

Conversely, the secondary bevel is the blade flat in Japanese descriptions, because it is of secondary importance to cutting,and is the second angle of the blade.
In Western descriptions, the edge angle is the secondary angle, because you put it on after the main angle.

 

[tryppyr]

Primary bevel to me means the one that determines the shape and appearance of the knife. The secondary bevel is the one you apply after the primary is complete. It seems to be a question of whether you look at it from the point of view of the process of manufacture or the usage of the finished product. As a maker, I am concerned more with the process.

Moreover, the edge that the Japanese consider primary is also the one that changes most over time, as the resharpening of the blade is done.

 

[james terrio]

I tend to think in the "western" way as you both described it. Because of both process and use; I choose or design a knife first based on the overall ("primary" in my mind) geometry... then I move on to deciding how acute I should make the edge. A purpose-built knife with an appropriately acute primary grind will still cut, even when dull at the very edge. Not as well as when it's nicely honed of course, but the basic wedge is still there.

A client can tweak the "secondary" or edge bevel to suit their needs, but it's unlikely that they're going to re-grind the whole knife.

It's also worth mentioning that the edge itself may have both a primary/overall grind angle, and a less-acute secondary or micro-bevel to add durability to a very thin cutting profile. This is basically the same concept as choosing the angles for the main bevels and the final edge, on a smaller scale.

 

[parbajtor]

I use western terminology and meaning

 

[Mark Behnke]

When in Rome do as the Romans do.

 

[Techtical]

It seems like we should come up with more universal terminology, edge bevel for the one that makes the knife come to a thin plane (knife shaped), and cutting bevel for the one that actually make the knife sharp... But that would probably be difficult to accomplish...

 

[tryppyr]

Incidentally, it occurs to me that on what Americans call "tanto" style blades, there would be multiple "primary" and "secondary" bevels. So yes, I think a new naming system is in order.

 

[Atlas Knife Company]

When in Rome do as the Romans do.

Took the words right outta my mouth.

 

[Stacy E. Apelt - Bladesmith]

What made me bring this up was an email from a person making a santoku. They said the primary angle was 20 degrees on a 2" tall blade. Some fast head math says that the spine would be about 3/4" thick. Then I realized he was calling the edge angle the primary, as it is often referred to in Japanese knife info.

 

[daizee]

I'm familiar with the western usage.

I bet if I learned the Japanese terms and matched them with my western vocabulary I'd never know the difference in the semantics and yet could still speak accurately against the two styles.

 

[fast14riot]

Well what happens when a tertiary bevel is added?!


-Xander

 

[Mark Behnke]

This might help:



http://www.bladeforums.com/forums/s...lade-bevels-grinds-and-sharpening-terminology


Maybe it's the step before convex?

 

[mgysgthath]

I also think in terms of the western definitions.. mostly as that's the only definition I knew. Now I'm confused, lol.

 

[Stacy E. Apelt - Bladesmith]

I am pretty sure 99% of the forumites are Western hemisphere folks ,or former colonials of a nation in that group, and use what we would call the "standard" definition. I was mostly curious about those not in the US/Canada/Central Europe/extended family. Especially non-English influenced areas like the Far east, South-east Asia, and Africa.

 

[Fred.Rowe]

I always discuss bevels, where ever they are located on the blade, in terms of degree of angle. Its easy to understand what bevel is being referred to, by the degree being discussed; as you noted in your conversation, Stacy.