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Sharpening angle

Wed Feb 26, 2014 11:38 am

I know most people say not to get to hung up on sharpening angle, but I just want to know if I got the angle "about" right. I have a Tojiro Shirogami Nakir and i'm using a Bester 1000 and 4000 followed by some leather stropping. The reason I'm asking is that I notice I can get my Takamura Migaki R-2 Petty sharper than the nakiri, and it looks like 15 degrees is more than what it looks like on many of the videos on Japanese knife sharpening. I can still get the Nakiri to push cut paper, so it is sharp, but just want to make sure I'm sharpening correctly.

I am sharpening both knives at 15 degrees. I made up a 15 degree clay wedge that helps me get the angle set about right when using the stones (see attached pictures). Is 15 degrees good for the Nakiri (give or take a few degrees)?



Re: Sharpening angle

Wed Feb 26, 2014 12:23 pm

In what way do you feel the petty is sharper than you can get the nakiri? Are you basing this on cutting ability, sound of paper, what? The reason I ask is because if you're using cutting ability and 15 degrees, the "shoulder" on the nakiri might be thicker than the petty.

Have you thinned the petty and/or nakiri at all?

Just random thoughts to throw out there.

Properly HT'd white steel in a nakiri that only sees action cutting veggies should be able to hold a 10 degree per side edge without much worry. Lower probably, really.

Here's a link to an angle trick using coins:

http://www.chadwrites.com/knife-sharpen ... le-finder/

Re: Sharpening angle

Wed Feb 26, 2014 1:23 pm

I'm really basing the sharpness on the feel of cutting. Take carrots for example. They both seem to start to cut very well, but the Nakiri seems to have more friction going through the body of the carrot. I guess that has more to do with the petty being very thin, and having very smooth/polished sides compared to the Nakiri, so there is less friction.

Maybe I'll try 10 degrees for the Nakiri (it's only used on vegetables) and see where that gets me.

I haven't touched the petty other than bringing it back up on a 4000 stone, but perhaps I should try thinning the Nakiri somewhat.

Oh, and thanks for the link Adam, very helpful... ;)

Re: Sharpening angle

Wed Feb 26, 2014 3:50 pm

Yeah, if you're basing the sharpness on cutting carrots and the nakiri isn't cutting them as easily....I bet the shoulder is too thick. Not a big surprise on the knife in question. Inexpensive, rustic knife with not a lot of time spent by the maker on the edge profile. The the shoulder down a bit, then put a 10 degree edge on the knife and it'll probably cut like a dream.

Re: Sharpening angle

Wed Feb 26, 2014 7:46 pm

First, please excuse my poor drawing skills!

I just had a close look at the profile of the blade. It seems the left side is straight until the secondary bevel starts, and then continues straight until the primary bevel, but on the right side, it almost seems like it's slightly hollow ground, and then the secondary bevel is curved. Does that make sense? I have exaggerated the curves on the right side of the picture.

If I was to thin this out, could I just use the stones on the left side only (I don't have a belt grinder, as I assume I would need one to keep the curve that's on the right side of the blade)?


Re: Sharpening angle

Wed Feb 26, 2014 9:55 pm

Uhhhh, I don't think i've ever seen a knife with a concave face unless it's a single bevel knife.

The takamura migaki is a very thin knife, especially behind the edge. The tojiro might need to be thinned a little to stop wedging which makes it feel dull when cutting ingredients.

Me personally I don't like a naikiri to be too thin behind the edge, sure it makes it that much sharper, but what I find most is that the edge might roll over easier.

I like my gyuto's thin and a crisp -15 dps edge. My naikiri I like for harder ingredients like carrots and squash. In general I'm a little more rough with my naikiri and I want the edge to last a little longer so it's about 15+ dps almost 20 dps. This means I can whack it around on the board all day long and it will stay sharp, especially through the tougher ingredients like I mentioned.

Re: Sharpening angle

Thu Feb 27, 2014 10:31 am

If you'd do me a favor of placing a straight edge on both sides of the knife.....take a picture....post here.

I'm afraid to answer your question before that.

Straight edge placed across the side of the knife from spine to edge.....picture taken to show what it represents.

Re: Sharpening angle

Thu Feb 27, 2014 10:50 am

Thanks for your help Adam :)

Hope the pictures make sense. Two pictures of each side. Left side has two straight angles, the right side has the concave shape starting at the spine and ending about an inch from the edge, and from there it's a convex curve to the edge.

In the pictures of the left side, the blade edge is on the left, and on the right side pictures the blade edge is on the right.





Re: Sharpening angle

Thu Feb 27, 2014 12:04 pm

That particular nakiri is meant to be a hacker of harder ingredients. Thin it out a little with the 1k...work in 30 second increments on each side of the blade and flip it over...It's not overly difficult to sharpen section by section. Just take your time and observe how the metal changes.

You can't expect that particular nakiri or most nakiri blades to have the thin profile of the Takamura. It's not the intended chore of the nakiri to be a super fine laser.

Re: Sharpening angle

Thu Feb 27, 2014 1:45 pm

Okay....so without actually being able to do this in hand:

If you want the knife to cut root veggies effectively.....you need to thin the shoulders. It can be done with a 1k stone, but if you're proficient with stone's I would much prefer something coarser....say in the 500 grit range.

I would first remove some of the shoulder on the left side....that looks a little thick to me. This might very well make the knife look ragged, but it will help it cut better.

If that works....stop there.

If not, work on the right side a bit. It's shoulder is also a bit thick, but with that knife, the overall grind isn't the greatest to be able to thin the right side without really scratching up the KU finish.
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