WIP question - Nakiri grind

[erezj]

I'm a (very) small time knife maker (so far 4 knives) and am finalizing my first Nakiri, 150mm san mai wought Iron/C125.

Hight: 52mm
Width above heel 4.5 mm
Width 1 cm from tip: 1.5 mm
(Thanks to Zweber12 for your great site and data: http://kitaeji.com/index.html)

I also have a good idea as to the grind from Kippington, 'A Basic Explanation of Asymmetry', https://www.kitchenknifeforums.com/...of-asymmetry.33951/?highlight=asymetric+grind

What I am still missing is the grind of the 'Flats' of the Nakiri.
I plan on a 70/30 bevel grind, but what about the rest of the 'Flats'. its so thin, there is hardly any place for Convex, S grinds or anything else, so how do you avoid stickatge with such a large flat?

Appreciate your inputs.

Love this forum!

 

[Jville]

4.5 does not sound thin. There would seem to me to be plenty of metal to produce convexing. Does it thin out immediately/ drastically?

 

[erezj]

4.5 does not sound thin. There would seem to me to be plenty of metal to produce convexing. Does it thin out immediately/ drastically?

Yes it does, 2.2 mm on spine in the middle, and due to the height, 52mm, it is challenging for me to see how can you create any grind which is not flatish.

 

[milkbaby]

Takeda is probably thinner than 2.2 mm at the spine (too lazy to find my knife and calipers to check tho, just believe me ) and his knives have a forged hollow in the middle similar to what an S grind achieves.

You have plenty of volume to grind a convex or even an s grind into the blade. You could do a compound grind with a scandi grind at the edge leading into a more acute flat as well. I just freehand a convex from edge to the spine and blend it best I can.

Not a great picture trying to hold the ruler with one hand and the phone camera with the other (the amount of convex is exaggerated here but for sure you can see it's not a flat grind) here's the one nakiri I made with basically almost full height convex. Less than 2.4 mm at the spine over the heel and 56 mm blade height at the heel.

Hopefully some of makers who are actually good at this will chime in.

 

[milkbaby]

Another strategy is a fuller ground in on one side only, obviously only done after heat treat. But you may have to straighten or otherwise adjust the blade after grinding it in regardless as it may still warp.

Also, check out the Salem Straub integral gyuto here:
Show your newest knife buy

Not sure of the spine thickness but the choil seems to show it's convex ground then also looking at the other pictures is also s grind in the middle.

 

[erezj]

The options of S grind and fuller are of the table since my cladding came out so thin (so happy I got the C125 through out the edge ) I dont want to go through the wroght Iron, so Ill have to go convex.
Thanks for the pics they were very help full.

appreciate more pics like the one showing the profile with a ruler as a reference,
and any advice on convex grinds for a Nakiri

 

[milkbaby]

You can try some practice grinds on cheap sacrificial steel or mild steel, that way you're just out the cost of the cheaper steel and abrasive belts.

In the future, you can try forging in the hollow like Takeda, as well. Good luck and make sure to post pictures!