Introduction: DIY Kiridashi Knives

Some time ago, I spent some relaxing days at my country house. I thought to make something with the few tools available there. What I had at hand were some tool steel and a small self-built forge. So I thought to make a couple of Kiridashi knives. The Kiridashi knife is a traditional wood carving knife, widely used in Japan. But it also is a marking knife, used by almost all the Japanese carpenters, as well as a versatile tool for general use.

Translated to English, 'kiridashi' means 'to carve out' in Japanese.

Step 1: Choosing the Right Steel

The knife steels I had at my disposal were some C70 (Aisi-1070) and some K720 (Aisi-O2). I chose to use a 5mm thick K720 because it is harder than the C70 and therefore more suitable for a knife like this that requires little flexibility but great sharpness.

Step 2: Marking the Steel for the Cuts

To begin with, I secured the metal to a desk with a C-clamp. Then, using a paper template and a Sharpie marker, I marked the shape of the two knives to be made.

Step 3: Cutting Out the Pieces

I then cut the two shapes with an angle grinder and a cutoff wheel. This operation is quite simple, you just have to be careful not to bend the wheel of the grinder and not to apply to much force when making the cut.
Always remember to wear all the necessary safety equipment when using an angle grinder. A face shield, in particular, is recommended.

Step 4: Hammered Decoration

I thought I would add a hammered texture on one of the two knives. This is for an aesthetic effect but also for a more secure grip. To do this I used a small forge built by me. The construction of the forge is very simple: I used a coffee can inside of which I poured some refractory cement. The heat source I used is a propane torch connected to a small gas cylinder. I then heated the knife to a red cherry color, hammering it repeatedly over a small anvil, made from a piece of railroad track.
During this operation, the knife tends to bend, so be sure to straighten it as far as possible before proceeding to the next step, otherwise sharpening will become almost impossible.

Step 5: Grinding the Main Bevel

The next step, after wearing all the necessary protections, was to create the main bevel of the knives. To do this I used a portable belt sander, mounted on a table I made.
The bevel should not create a sharp edge, at this point. It is necessary to leave about half a millimeter thickness to avoid ruining the knives in the next hardening step.

Step 6: Hardening

The hardening phase consists of bringing the steel up to the temperature where it no longer attracts a magnet, then quenching in oil. For this type of steel, the ideal temperature is about 800° C (1472° F), which corresponds to a cherry red color. For quickly cooling it (quenching) I used a canola oil at a temperature of about 50° C (122° F). I apologize for the dark image, but it helps to better understand the color of the metal at the moment of the quench.

Step 7: Tempering

Now the steel should be very hard so that a file should skate right off of it without leaving a mark. But it is also brittle, so it is necessary to temper it to give it some elasticity.
Not having to make the knives particularly flexible, but opting for more hardness, I put them in the oven at 200 ° C (392 ° F) for 60 minutes.

Step 8: Pre-sharpening

At this point, the knives can be sharpened. After the hardening, however, it is necessary to avoid overheating the metal because too much heat on the blade will damage the heat treatment previously made.
The belt sander can still be used but with a fine paper, a low speed, and continuously wetting the blade in fresh water. As you can see from the photos, I do this with bare hands so that I can immediately feel any increase in the knife temperature. First I flatten the bottom of the knife, and then I sand the bevel until it meets the flat surface of the underside. This is a pre-sharpening because the final sharpening have to be done manually afterward.

Step 9: Final Sharpening

For the final sharpening, I first used some diamond stones, up to 800 grit and then a couple of Japanese water stones, up to 6000 grit. For the final polishing, I used an abrasive paste on a leather strop.

Step 10: Final Shots

Here you can see some shots of the finished knives.

In the video on my YouTube channel, you can also see the cutting tests I've made to see the functionality of these knives, as well as have a better perception of the various steps.

Thank you for checking out this build.

Comments

author
ZeRandomMan (author)2017-08-20

Do you sell them in Kickstarter?

author
robbtoberfest (author)2017-08-17

Beautiful!

author
andrew88con (author)2017-08-16

awesome

author
cicero.v.a (author)2017-08-16

Parabéns!

author
jerry.ericsson2 (author)2017-08-14

I tried my hand at making a few knives when I was in my gunsmithing phase of my life, a couple turned out passable, one with real stag handles and one using walnut from an old gunstock. For steel, I used old files that had passed their use by date and no longer filed as well as they should have. It was great fun but when my blasted belt sander broke free from it's stand, and I did the natural thing and tried to grab a running belt sander to keep it from crashing into the floor. Man what a mess my right hand was; really messed up my day and put an end to my knife building days. My hand did eventually heal up, and you can't even see the scars any more, but I gotta tell you, that year when I wet to qualify with my hand gun, shooting left handed worked but I didn't get my normal average, instead of tying for the top where I usually did, I nearly tied for low score. That said, I am now stronger then ever in the weak hand portion of qualification.

author
DdpapaR (author)jerry.ericsson22017-08-16

One thing I learnt in my early twenties is to never try to catch a flying jigsaw. When cutting out a laminate worktop for a glass kitchen hob I lifted the jigsaw when the blade was still active. The jig saw blade just nicked the work top and flew forward. Instinctively I went to stop it with the left hand, but cut through the leather glove I was wearing right through to the bone on my wedding ring finger.

I consider myself lucky I didn't take the end of my finger off.

Rule number 1 if anything can cut and its moving treat it safely as it will always find skin and bone

author

It sounds painful! Thank you for sharing your experience.

author

As he brought forth a real Hazzard I would suggest using a foot pedal switch for the sander that way if the sander breaks away as his did you step off the foot switch and the power is turned off !!

author
Ogle5316 (author)jerry.ericsson22017-08-15

The first rule I learned in wood working, metalworking is "Let it fall."

When a heavy object that you own falls in your proximity, you no longer own it until it is stopped on the ground, it owns you.

author
Zaacharia (author)Ogle53162017-08-15

I work with glass (and knives) - never, ever catch a falling sharp (or buzzing) thing. I grabbed a piece of falling plate glass I was working on and let go immediately - my fingers were sliced to the tendons, but did not actually touch the tendons. It scared me spit-less but I learned; now, as soon as something begins to fall, I step back and let gravity take its course.

author
justiniano (author)2017-08-15

Is a beautiful job and need a lot of patience I imagine the Samurai maker congratulations and God bless,

author

Many thanks!

author
Zaacharia (author)2017-08-15

Those are beautiful! I would display them as art!

author

Thank you very much!

author
stepinfech (author)2017-08-15

Very
Nice Job. I have made similar knives using old turbine blades from our
ships exhaust system

author
Hewettc (author)2017-08-15

Nice work! Love the hammered finish. Good explanation of your process.

author

Thank you very much!

author
RKE2 (author)2017-08-15

Very nice. I'm curious about the hammered pattern. Did you just use a ball peen hammer or something that has a texture to it?

author
Guido Vrola Design (author)RKE22017-08-15

Thank you. I have used a common ball peen hammer. What makes the difference is your eye...

author
DaveO4 (author)2017-08-15

Very nice work. I'm going to give it a try as soon as I can. I've wanted to try making a knife for a long time and this seems like the perfect place to start.

author

Thank you! Hope to see your try...

author
Copyu (author)2017-08-15

They're beautiful and your 'instructable' is excellent! Well done.

I like tool and knife-making, but am limited to using the 'stock-removal' method, since I can't operate a forge in (or outside of) my apartment.

I've never considered making one of these, as I live in Japan, where they're $6-10 in most hardware stores and home centers and made of great steel. The ones I own are a bit longer than the ones in your photos.

For potential "woodworking" makers, you really need to make two—left and right bevel, you got it?

author
Guido Vrola Design (author)Copyu2017-08-15

You are right about the need for left and right knife. I know, that good hand forged kiridashi can be quite expensive.

author
Stephen_Hampton (author)2017-08-15

One question... you said you tempered at 200 degrees Celsius for 60 minutes for more hardness and less flexibility.

If I wanted more flexibility, would I increase the temperature or increase the tempering time?

(The steel you chose is popular for quality bushcraft knives, but it needs to be a bit softer for easier sharpening and also less brittle for rough handling)

author

As somebody said, you can do both. The oven in your kitchen, however, can probably not go much beyond that temperature, so it is advisable to increase the time.

author
Xexos (author)Stephen_Hampton2017-08-15

You can do either, however, increasing the temperature is generally considered to be more effective than increasing the tempering cycle time. Some people prefer to do multiple cycles (the blade is tempered for an hour, air cooled, then tempered again for an hour). A lot of it depends on what steel you plan on using, I'd recommend looking up "Heat treat information for [your steel here]"

author
theThinkerator. (author)Xexos2017-08-15

I think you better research that... I thought you would heat it to a lower degree... timing is not important, only that the heat is soaked into the metal to the point you want softened

author
Xexos (author)theThinkerator.2017-08-15

Tempering reduces hardness and increases toughness. The higher the temperature the more it reduces hardness and the more it increases toughness. Tempering for a longer time will also have a similar effect to raising temperature, just not as pronounced.

author
Alex 2Q (author)2017-08-11

Great design! I love to make kiridashis myself and will look to try that hammer pattern too.

author
Alex 2Q (author)Alex 2Q2017-08-11

The sanding table for your belt sander is also a cool and simple idea I might steal ;)

author

It a very simple jig to make. The only thing you have to pay attention when using it is that if you handle the piece in the wrong way it can jump away like a bullet. And if the piece is a kiridashi...you know...

author

Thank you Alex! It's a way to start going a little bit more toward "hand forging" side.

author
Peterthinking (author)2017-08-09

Very nice. But if I may make a suggestion I have a knife much like this. It is very comfortable and cannot slip in your grip.

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author

Thank you for the suggestion. I'm not a fan of the ergonomic solutions that force you to a predetermined position. There
are many different ways to use these tools and many ways to handle
them, so a more neutral grip is, in my opinion, to be preferred.

author
deluges (author)2017-08-10

Beautiful. Great work

author

Thank you very much!

author
Djjazzyjasper (author)2017-08-10

Awesome knives

author

Many thanks!

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Bio: I am an industrial designer and a maker. I like to make prototypes, unique pieces, equipment and other stuff. In this channel I will show ... More »
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