Knifemaking Tutorial: Japanese Kiridashi

So you want a blade?

I'm presenting here a basic set of instructions to make a neat little kiridashi; a small Japanese blade traditionally used for woodworking, carpentry and leatherwork. They make an excellent utility, woodwork, or compact knife for every day carry, perhaps as a neck knife.

I'm using stock removal techniques here, but forging can be used quite easily due to the simplicity of a kiridashi. I have some tools that few people will have access to- so as I go along I will offer alternatives for those who don't have the same level of tooling. This is suitable for beginners, and could even be used as a first knife project. You will need some metalwork skills and common sense. If you've never tried knifemaking before don't expect perfect results on your first try

Step 1: Tooling and Material Selection

Tools and peripherals required:
     -Saw or grinder with cutting disk (to rough out the blade)
     -Bench grinder or angle grinder with grinding/sanding disc (to rough grind the blade)
     -Vise, pliers/vise grips, clamps etc
     -Belt grinder (rough grinding and shaping)
     -Assorted files and sandpaper, sanding block
     -Forge, propane torch, grill or small fire
     -Drill and bits (if you want a lanyard hole)
     -Oil or water for quenching, suitable for the steel you choose 

A note on steel selection:
You need to use a good quality carbon steel which can be hardened and tempered. For the beginner without controllable heating equipment also avoid stainless steels as they can be tricky to heat treat. Don't use mystery steel that you don't know the composition of. Odds are you'll end up with junk that can't be hardened and will make a crappy shank, not a knife.

Good steel can be bought commercially or found in lawnmower blades, coil and leaf springs (coils will require forging), old saw blades, and old files. Don't chance it with junk

Step 2: Design and First Cuts

Before you start haphazardly lopping into a piece of steel, take some time with a sheet of paper and sketch out a shape, including the position of grinds, lanyard holes, grips or thumb grooves. For your first few knives, look through google images first to get an idea for a good layout that's visually appealing and comfortable to use, then modify it to suit yourself. Asides from poor material seletion and lack of practice, poor design is the biggest killer of knives made by beginners.

When making the design consider the steel you're using. If you don't want to add a cord wrap or scales (handles) then use a thicker piece of stock- a thin piece of metal without a handle will be very uncomfortable and unsafe to use.

Once you've designed your knife, transfer it to your piece of metal. You can glue or tape the design on, or trace the outline with a paint pen, scribe or permanent marker.

NOTE: If you trace an outline, make sure your final grinds/filing coincide with the inside of the line, or you'll add unplanned extra material to your knife

Using an angle grinder or hacksaw (you'll need annealed steel to use a hacksaw, see the next steps on how to do this) cut out a rough outline of your part without going inside the lines.

Warning: Be careful when using power tools, especially angle grinders. Make sure your work is held securely in a vise or clamp; always use two hands on the tool and wear glasses and ear protection. Use pliers to handle the workpiece as it will be hot after cutting and often will have sharp edges

Step 3: Annealing and Rough Grinding

Once you've cut out the rough shape, if you're using steel that's already hardened you'll want to anneal it now. If you're only using power tools and don't take pride in your work (or want to spend a thousand hours sanding) then feel free to skip this step.

When we anneal a piece of steel, we're basically making it softer to make it easier to work with and take less of a toll on our tools.

The easiest way to do this is in a small forge. Heat up the metal until it gets an orange glow, then shut off and close the forge, letting it cool down slowly. Alternatively you can use a torch to heat it then stick it in some sand, or put it in a small fire to heat it up and leave it in there, letting the fire die down slowly. Essentially we want to get it really hot, then cool it down slowly.

Once your steel is cooled down and is now softer and easier to work with you can start grinding out the shape of your knife. For this you can use an angle grinder, bench grinder, belt grinder or files. Grind until the workpiece is smooth and you've almost reached the outline.

Now using the same tools, you can start grinding the bevel (removing metal to make the blade). It's worth noting here about handedness. A "right handed" kiridashi has the ground surface facing away from the user when held in the right hand, and a "left handed" kiridashi has the ground bevel facing away from the user when held in the left hand. A kiridashi is traditionally only ground on one side, the other side being left flat like a woodworking chisel. If you desire you could also make the grinds even on both sides like a more conventional knife.

A kiridashi being left or right handed doesn't mean it can only be used by a person who is left or right handed, respectively. They'll simply work better in different situations; some people will even own a set consisting of a left and right handed kiridashi. If you're only making one, then go for one that matches your handedness, or one with even grinds (a chisel ground knife makes a better woodworking tool though)

Do not completely finish grinding the bevel by this method, especially if you're using a tool with a hard grinding surface- this is liable to leave deep gouges that you will never get out of your knife.

Step 4: Fine Grinding and Heat Treating

Now you have your roughly ground blade it's time for the hard work... getting it smooth.

First of all, assuming you want to do a flat grind (if you don't know about convex or hollow grinds yet then don't worry about them, a flat grind is most suitable for a kiridashi anyway) you'll need to get the bevel(s) completely flat. This needs to be done with a belt grinder or fine toothed file; keep the work at the angle needed and keep it straight and flat. If you have gouges in your blade you'll never get a good looking knife. 

Once you've done that, wrap some rough emery paper (eg. 80 grit) around a fine file and start sanding the work, keeping it flat.

Note: Always use a solid, flat, straight backing when sanding. If you don't you'll grind your blade unevenly, and end up with a rounded surface (convex, but done wrong)

Once the workpiece is smooth and the scratches from the belt sander/file are removed you can go up to a finer emery paper eg. 120 grit. Every time you go to a finer emery/sandpaper alternate the direction by 90 degrees- this removes the scratches from the previous, coarser sandpaper. Work through emery paper and sandpaper, alternating directions, until you reach 400 grit. Then you can use wet and dry sanding paper, wet with water (rust isn't an issue at this stage). Reach at least 400-600 grit on the bevel before moving onto heat treating.

Note: It may seem weird to do all this work then throw your nice smooth knife in the forge, but the more work you do now the easier the scale is to remove, and the less work you'll need to do when the knife is hard.

I chose to not polish the sides, and to just hand rub them with some 240 grit sandpaper. I then used a large hammer on the flat sides to make a forged look (if you're forging the blade you can leave the sides alone if you wish and only grind the bevels). Alternatively you can grind and polish the sides.

Note: If you're adding a handle, you MUST grind the sides flat, or it will look like junk. Do not add the handle yet, however

To heat treat your blade, you need to heat it up to it's curie point and then quench it in oil or water (note this is a simplified method, some steels will require different techniques- to be safe, google or ask first). Heat the blade in a forge, with a torch or in a fire until the metal will no longer be attracted to a magnet. This is it's curie point.

Once the metal has reached this point, remove it from the heat and QUICKLY place it blade first into the oil or water, only immersing slightly past the ground bevels- this makes the blade very hard, but the rest of the knife more durable.

Once the blade has finished quenching, remove it from the oil/water and let it cool down.

Once the blade is cool, start with a mid grit sandpaper (eg. 240) and start the sanding process again, working up to at least 400-600 grit, preferably 1200-2000. Always use a flat, hard backer like a file or cork sanding block and work at the same angle as the bevels. Here you're working to your final grit. Refinish the sides in the same way you did before.

Now you need to temper your blade- this is reducing the hardness to make the edge more flexible and durable, without sacrificing too much hardness. 

This can be done by placing the knife in an oven at 200 celsius for about 2 hours. Otherwise, you can use a torch or heated tongs to heat the spine/body of the knife- as the knife is heated some oxide colours will be produced. For a kiridashi you're looking for a light yellow straw colour. Look up a chart of colours so you know what to look for. If you go too far the blade will be soft, and will need re hardening. As soon as you get this colour cool the blade in oil or water. you can then resand with the last grit you used (eg. 1200) or leave the colour there if you like how it looks.

Step 5: Filework and Finishing

Filework is a way of adding a decorative finish to the back of a blade; it also serves a similar function to a traction groove. It's not nessecary and can be skipped if you want

It is done with a variety of files, here I'm showing a vine filework which needs:
     -Triangular file
     -Small round file eg. chainsaw file
     -Rats tail round file
     -Half round file or a flat file with a smooth edge

1. Mark out lines on either side in half inch increments, offset on either side by 1/4". I marked out with a paint pen and thin black permanent marker.
2. Using the triangular file, make small grooves on each of the marks, at 45 degrees. These act as pilot grooves
3. Use the small round file, make round grooves at 45 degrees, using the triangle marks as guides to start the filing
4. Repeat this process, using the rats tail file to enlarge the round grooves
5. Using the half round or flat file, round and transition the edges of the grooves, making wider grooves
6. With the fine marker, mark the centre/high point of each round groove on the opposite side of the edge
7. With the triangular file, VERY lightly make small grooves on these marks to act as starting grooves.
8. Angle the file down so one side is almost touching the workpiece, then working in a semicircular pattern make a groove in the shape of a thorn

Note: Filework is tricky to get the hang of. Use the instructions in conjunction with the pictures to get the pattern right (this produces a vine with thorns). If you're unsure, googling "knife filework" will show more patterns and instructions. Try this on a scrap piece of steel first, it will take a few tries to get nice- work slowly and evenly

Apologies: I didn't get any pictures of making the triangle grooves, the last picture has a thorn on it- this is the result you're looking for. Check the other photos for filework close ups

Note: Filework should be done while annealed, or done on a blade that has a softer spine (as my instructions, if followed, will make). Diamond files can be used for filework on a hard blade. Doing filework pre heat treating will result in some scale forming on the filework- when I'm going for a forged look I like this finish, so I just polish the raised parts with wet & dry and leave the rest black, as they came out the forge. It can be removed with filing or an acid etch (not recommended).

To finish your knife, ensure it is clean and sanded and polished (where you want it to be). If you want you may use a buffing wheel and compound to put a mirror shine on- I feel this is a cheats way in a traditional knife, and 2000 grit wet and dry makes a good finish. To sharpen the knife, grind the flat side flat, sitting on a bench stone, with a small secondary bevel on the bevelled edge. Finish by stropping or with a steel. For a woodworking and general purpose knife I make my knives razor sharp- literally sharp enough to shave with. There's no point in going sharper for me personally- if you need a sharper knife for delicate work use a scalpel

Step 6: Results and Evaluation

Now it's time to look at how your blade came out. Do an honest critique, but don't get disheartened. I know I turned out a few junk knives (and from some makers perspectives, I probably still do) when I began. If you used the right steel, hardened, tempered and sharpened the blade properly, then you should have a usable tool. A better surface finish, more intricate designs and better overall fit and finish come with practice and hard work.

I'm going to upload some photos of the last Kiridashi I made. I'll point out where I'd improve next time

With some practice and the right tools these little knives can be turned out pretty quickly (in comparison to large knives), and they don't take up much stock, making them good gifts. It's just a shame all my friends go for big, impractical knives.. One got a bowie for his birthday from me and another is getting a mace

Body: I should have gotten it hot before I did the hammering, for a better forging look
Blade: Next time I'll probably do an etch to bring out hardening lines
Filework: I need to invest in a few different shape files. I'll probably use a rough buffing wheel and cutting compound to get into intricate grooves I can't read with sandpaper
Edges: Probably a finer finish next time, maybe 600 grit instead

If you have any questions about the process or want feedback or advice feel free to leave a comment here