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The Blade Road

Mon Feb 25, 2013 7:21 am

A recent encounter with a single beveled knife has generated some questions, I'm hoping some of you with more experience sharpening Yanagi-ba's for example will help me out.

I found it very difficult for the entire Blade Road to make full contact with the water stones, which are very flat by the way. I don't mean the entire BR at at a time, I mean certain spots could not be reached. Regardless of how I held the knife, or where I placed my fingers on the back, a few spots could not be touched. I painted the entire BR with a sharpie and could reach
80% of it.

-This was the first sharpening for this Usuba, is this a common occurence with single beveled knives?

- Is it imperative to get to the point where the entire Blade Road will make contact with the stones or whatever it is you are using to sharpen?

- Is it just a matter of using a coarse stone, a lot of elbow grease to achieve a perfectly flat Blade Road?

Sharpening the knife was no problem whatsoever, it became extremely sharp and that happened very quickly. I am concerned having a uniform appearance for the BR when the work is done.
This was a mono steel knife and I was shooting for a highly polished appearance.

I realize with laminated knives that this is not the desire, I just assumed that that Blade Road would sit nicely on the stone......nothing is easy is it.


Re: The Blade Road

Mon Feb 25, 2013 8:13 am

Most single bevel knives are ground on a wheel and thus the blade road is most usually concave.

No, it's not imperative to have the entire blade road flat. In fact, some will argue that it should be concave while others argue it should be convex (hamaguri edge)

Yes, if you want a perfectly flat blade road, get out the band-aids, ointment, a six pack, your coarsest stone, and the Star Wars series (all 6 of them even though the last 3 all sucked)

That this was on a mono steel knife made your job a lot harder. In order to make the blade road flat, you had to grind all hardened metal on probably a piss poorly made knife. On a kasumi knife, this wouldn't have taken as long.

Re: The Blade Road

Mon Feb 25, 2013 8:32 am

Thanks Adam,
This makes me feel better and yes I will watch all of the Star Wars series, even the last ones which should have been the first ones....good thing they weren't though.

I have a feeling that Chef is going to give me his Yanagi-ba, so I will see how that one goes.

Thanks for taking the time to reply.

Re: The Blade Road

Mon Feb 25, 2013 11:22 am

Actually the bevel is convex not concave and when sharpening you will use two angles with two different placements of pressure from your fingers.

Here is a video I did on sharpening a yanagi it will probably help to answer some questions.


Re: The Blade Road

Mon Feb 25, 2013 11:35 am

Hi Jason and thanks for the response.
I will need to wait a bit to watch the video but I believe I have seen it before, several times and I really enjoyed it.
In the case of the Miyabi I did, I don't think the blade road was convex but that was a mono steel knife.
The Yanagiba I will be getting is laminated, so yes, I get it now.
Naturally the entire Blade Road will not rest on the stone if it is slightly convex so as you say, finger placement on the back is key to ensure I am hitting the right spots, i.e. from the Shinogi Line down to point where the two metals blend together and then from point down to the edge.
(it helps me to understand when I spell it out like this, but feel free to let me know if this statement is incorrect)

I'm going to watch your video again Jason, your reply and link is much appreciated.

Re: The Blade Road

Mon Feb 25, 2013 11:49 am

Jason -

Are you talking about a specific knife having a convex blade road, or that they should have a convex blade road, or that all come with a convex blade road.

If the later, I've seen a lot of yanagi come with a concave blade road...in fact, most of them do.

Re: The Blade Road

Mon Feb 25, 2013 1:57 pm

Jason, watched the video once again.
Correct me if I am wrong. The objective with the coarse stone, in your case the Nubatama 120 is to flatten the Blade Road. It is slightly convex as you mention but your goal is to create a uniform scratch pattern, make it as flat as possible. The convex where the two metals meet is re-established in later stages

Do you agree?

Re: The Blade Road

Mon Feb 25, 2013 4:14 pm

Adam, I'm sure that is the result of the wheel but in hand sharpening it becomes convex as I'm sure you understand. As you sharpen the large "Blade Road" it will almost tell you how to sharpen it, if you can let the feedback guide you. And NOW I see where I mixed up the blade type :oops: MONO STEEL (where's the face palm smilie when you need one)


Whenever you sharpen on a stone you only make contact with a very small area, so a large "flat" area will become convex from sharpening on a "flat" stone. To make something perfectly flat it would have to be infinitely rigid, but then you would have broken the laws of physics.

Re: The Blade Road

Mon Feb 25, 2013 5:07 pm

I understand thank you.

With that mono steel blade road that I dealt with, in order for me to achieve a completely uniform scratch pattern across the entire surface of the BR. I needed to flatten it with a coarse stone. This was for appearances only though.

Re: The Blade Road

Mon Feb 25, 2013 5:50 pm

Yeah, we're on the same page. Thanks!
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