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Dave Martell
08-15-2011, 07:45 PM
I've been asked often (a lot lately) about how the Japanese shape the sides of their knives. I usually explain it by saying something like, "they use multiple bevels along the length, sometimes two or three or even four bevels".

Below is a knife that I got in for thinning the blade that shows my first pass on the belt down the length of the knife. I laid the knife down flat on a dead flat platen (that's 9" long) and you can clearly see that the belt only touches in a 1" (or less) section along it's length.

These pictures demonstrate how this knife is ground with multiple bevels along the blade. I hit the middle bevel but there are still two below and one above plus the edge bevel also.

I hope this helps some of you more clearly see how these knives are ground.

obtuse
08-15-2011, 07:51 PM
Very cool, thanks for showing us this. I don't recognize the knife, what is it?

Dave Martell
08-15-2011, 08:10 PM
Hiro AS wa-sujihiki

obtuse
08-15-2011, 08:33 PM
Of course, I should have been able to tell by the cladding. I failed.

Dave Martell
08-15-2011, 08:55 PM
Of course, I should have been able to tell by the cladding. I failed.


Nah, not so much, it's barely noticeable in the pictures.

apicius9
08-15-2011, 09:21 PM
My first thought was 'I would smack you if you did that to my knife' - but then I saw the final outcome and all is well :)

Stefan

Dave Martell
08-15-2011, 11:21 PM
It looks bad doesn't it? That's 80x right there....a well worn 80x though. That same belt would skid on O-1 but tears through this cladding like it's rubber.

Daniel Fairly
08-16-2011, 12:41 PM
Interesting, thanks for sharing.

monty
08-16-2011, 02:02 PM
Dave, do you try and conform your grinding to the existing bevels, or do you essentially blend them all together as a result of the grinding process?

Dave Martell
08-16-2011, 05:12 PM
Dave, do you try and conform your grinding to the existing bevels, or do you essentially blend them all together as a result of the grinding process?


I try my best to follow what's already there, replicate what the maker put into the knife, but the truth is that this is impossible to do exactly since we use different machines and techniques.

Dave Martell
08-16-2011, 05:13 PM
For the knifemakers reading this, that pass I did was with pressure. To hit the other bevels I had to rock (or twist) the blade.

jmforge
08-16-2011, 05:24 PM
Dave, can you easily see the different bevels on the surface or have they been blended enough that you have to really look for them?

Dave Martell
08-16-2011, 06:09 PM
You have to really look for them in the light or with a straight edge, they're always blended well.

JBroida
08-16-2011, 06:22 PM
yeah... my experience is that its usually 3-4 bevels for the entire surface and edge of the knife (on double bevel knives)... blended together with a little wrist action and the finished on wheels/stones until its damn near impossible to tell whats going on. I've watched the guys doing this countless times and it still amazes me.

jmforge
08-16-2011, 06:26 PM
What is more amazing is that the seem to be doing it some cases to a price point so they have to be able to do it quickly and efficiently. I have seen knives by guys like Bill Moran where the blade has been shaped from multiple grind lines/bevels to an almost perfect shallow convex, but they they have a LOT of hours in them and are priced accordingly. No substitute for skill, experience and a pair of Mod 1 Calibrated Eyeballs.
yeah... my experience is that its usually 3-4 bevels for the entire surface and edge of the knife (on double bevel knives)... blended together with a little wrist action and the finished on wheels/stones until its damn near impossible to tell whats going on. I've watched the guys doing this countless times and it still amazes me.

JBroida
08-16-2011, 06:30 PM
like this ;)

http://www.youtube.com/watch?v=aU6u80Hyw5Y

Marko Tsourkan
08-16-2011, 06:38 PM
yeah... my experience is that its usually 3-4 bevels for the entire surface and edge of the knife (on double bevel knives)... blended together with a little wrist action and the finished on wheels/stones until its damn near impossible to tell whats going on. I've watched the guys doing this countless times and it still amazes me.

A good finish can do magic to blending bevels. Watanabe comes to mind as a good example of that.

M

JBroida
08-16-2011, 06:45 PM
i totally agree