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Japanese Knives


Conner Michaux
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I recently was researching and reading about tanto knives and I came across something called a Ko tanto

so I looked further into the internet trying to find information on these, I found an old wip thread on this forum of someone making one. That and his website is about the only thing I can find on these knives, is the Kotanto actually a real thing or is that just someone’s take on a traditional tanto? If not what are the origins of this knife? I would also like to know about the construction of these blades, edge geometry/tang shape/handle construction etc 

i would like to make one of these Kotanto knives as historically accurate as I can but I don’t know where to look to learn how they were constructed. Thanks

Edited by Conner Michaux
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It's not really a take on a traditional tango, its mostly a descriptive term to describe a tanto that is shorter than most, but still has the blade width and depth of a traditional tanto. In American slang we might call it a stubby blade. The prefix "ko" just means child. So taken in context it would basically mean short tanto.

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What Brian said. Ko means small, O means big.  As for how to do it "right," first you choose your design school, then you make it short.  Look at anything at all by DaveJ, www.islandblacksmith.ca. He's the current go-to guy for all things tanto.  Start here: http://islandblacksmith.ca/2019/01/eyes-on-the-spine-say-no-to-the-kink-and-yes-to-the-flow/  and then the one you probably found already here: http://islandblacksmith.ca/2016/08/process-making-the-mountain-kotanto/

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Does anyone know if there are Sen scrapers for sale somewhere on the internet? I don't think I can make one so im trying to find one (if any) for sale.

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Why can't you make one?? Lack of materials or know-how? They are a stupid simple tool design wise. Get an old thick farrier's rasp, taper the two ends to fit into handles leaving 1-2 inches proud in the middle. Give it a flat bottom, with about a 25 to 30 degree bevel on the other side and then harden it. Just take the edge off the brittleness with a quick temper, sharpen it and there you go.

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When you put it like that it seems much more simple, but I dont have a rasp. Would it be possible to make on out of an old half round file? Ive got an old save edge usa half round I can use, its about 1" wide and pretty chunky,

 

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How’s this? I based it off of one of the Kotanto knives on the website Alan linked up there. It’s got the “fancy spine” as I am calling it because I don’t know what the Correct term for it is. Blade length is just over 4”

176B5F73-8D8E-494A-B3F4-7378019C8FA9.jpeg

Edited by Conner Michaux
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I dont think your cross section you've drawn is right.... But I dont know a whole lot about Japanese stuff. I think you'll want "hira zukuri" (full flat or lenticular). This I think is sort of shinogi zukuri (is that the right word?) But even for that, your primary grind would be taller. 

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Yeah I dont know pretty much anything about these :blink: but i'm just following what this article says.http://islandblacksmith.ca/2016/04/making-a-mountain-tanto/

and trying to learn as much as i can. So far as i know, the bevels are forged full flat and then that other bevel (I think thats the edge) is filed it. Looks like ive got more research to do!

Edited by Conner Michaux
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Dave J's Satoyama knives are his own personal take on a rustic tanto design, but they are not really traditional per-se. You would be better off concentrating on the first link Allan provided, which shows a good classical shape for a ko-tanto - pay particular attention to the tapers, angles and the shaping of the nakago. You need to learn the rules before you know how to break them.

 

The santoyama knives are forged very close to an edge, which is cleaned up with a file to prevent cracking in the quench, and then fully sharpened on a stone. The change in angle between the primary and secondary bevels is just to avoid ruining the forge finish. It's really no different to a Tim Lively or Raymond Richard forge finished western blade, but it's a modern conceit.

Jake Cleland - Skye Knives

www.knifemaker.co.uk

"We can't solve problems by using the same kind of thinking we used when we created them."

"Everything should be made as simple as possible, but not simpler."

"Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe."

 

Albert Einstein

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Thanks for the input. I drew up another 2 designs. Here is the one I think is the best, it has more of a taper towards the tip, I tried to base this one off of a full sized tanto and then shorten it.

image.jpg

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Go to that first link and look carefully at the blade cross section on the far right of the first white box.  That is hira-zukuri, or full flat grind, which is by far the most common for tanto.  If you go shinogi-zukuri (having a ridgeline on the flats) that ridge or shinogi has to be about 1/5 of the way down from the spine to the edge.  Japanese blades like this are sharpened to a zero edge, meaning there is no secondary bevel at all.  You polish from spine or shinogi to edge until it is sharp.  

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Thanks Alan, Im trying to understand the best I can. I am not totally sure what I will do for the bevels yet, but in my drawing above is the blade and tang shape accurate? 

If I am understanding correctly this is shinogi-zukuri? This is the picture off of Dave J's website. 

 

tools-for-satoyama-mountain-7.jpg 

 

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11 hours ago, Conner Michaux said:

Thanks Alan, Im trying to understand the best I can. I am not totally sure what I will do for the bevels yet, but in my drawing above is the blade and tang shape accurate? 

If I am understanding correctly this is shinogi-zukuri? This is the picture off of Dave J's website. 

 

tools-for-satoyama-mountain-7.jpg 

 

nope, that's Dave's satoyama style, like Jake said.  What you want is no visible transition or bevel from that angle. Full flat from spine to edge, no secondary bevel at all.

Oh, and the profile in your drawing is fine. B)

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Okay I get it now, thanks for the help.:)I will try making the sen today and I’ll start working on the blade This week.

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First attempt of forging this tanto, I think its decent. but there is a bit of curve in the spine and i had to hot cut the tip and reforge it so there is a bit of a burr that the dull hot cut left.

but other than that its pretty close to the drawing.

thumbnail-5.jpg

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Forged the tang and spike straight, and I’ve started drawfiling the bevels and shaping the profile. Is there any issue with the bevels being convex? Filing perfecting flat seems close to impossible. 

image.jpg

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I think it’s a cold shut, one wild hammer blow put an ugly dent into the edge, when I tried forging it flat it rolled over. And then that created a little stress point and cracked through the edge. I’m pretty sure that’s what happened. Oh well I’ll just go forge another. 

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