Process of Carving & Shaping a Tanto Tsuka

Once the habaki is made, it is time to create a handle for the blade. Before starting to carve the wood core, any additional hardware such as seppa (washer), tsuba (handguard), fuchi (ferrule), or kashira (pommel) are usually made. Because of the tapering shape of the tang, the handle can be designed to be easily removable for cleaning and sharpening the blade. If the handle is to be finished by wrapping with rawhide, leather, or ito (flat silk cord), these must be also planned into the design. The kotanto depicted here will have an all wood handle with a samegawa wrapping and no tsuba, so the only additional hardware required is a seppa, a thin metal washer for the habaki to shoulder against.

A tsuka is created in two distinct stages, first the wood is split and the inside carved to receive the tang, and then it is joined back together and the outside is shaped. To increase strength, the tang is placed slightly off centre in the block so that the nakago-ha (bottom edge of the tang) is fully supported by wood rather than resting against the glue joint.


Making the Seppa

The seppa may rest against the tsuba or fuchi, or in this case against the front of the tsuka. The outline of the seppa will determine the profile of the handle so it is very carefully planned in the context of the finished project.

The opening should be large enough that the tang does not actually touch it but small enough that the habaki can cover it. A punch is used to spread some material from the the top and bottom corners and they are adjusted to grip the corners of the nakago mune and the nakago-ha. Seppa are usually fairly simple, but various patinas, filework, hammer textures, or chisel marks can be used to add interesting details.

Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Copper water pipe is annealed in the forge, split with shears, opened, and hammered flat.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
A rough opening is cut with a small chisel, as large as possible while still leaving enough room for a clean filed edge.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
The nakago-ana is enlarged and cleaned up using escapement files.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Measuring from the top and bottom of the habaki rather than from the opening, the shape is laid out and chiseled, cut, or filed and then polished on waterstones.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
The finished seppa provides measurements to sketch out the rest of the koshirae.

Carving the Nakago-ana

The core of the handle is traditionally honoki (朴の木, hou wood, Japanese Bigleaf Magnolia, Magnolia Obavata), and my favorite local island stand-in is Nootka Cypress as it is a similar density clear, straight grained wood that carves nicely and provides a comparable cushioning and strength for tsuka and shirasaya.

Creating a tsuka is begun by selecting an appropriate block of wood, sawing or splitting it into halves, and carving out of each half to seat the tang in place. Carving is done with purpose designed chisels called saya-nomi. The nakago mune should be centered in the block of wood but the nakago-no-ha (bottom edge of the tang) should be fully seated in the omote half of the wood, slightly to one side. The purpose of this is to keep the tang from placing strain on the glue joint, resting it fully against wood. When the fit is just right and the tang sits tightly in place, the two pieces of wood are joined back together with sokui (rice paste glue), and the handle carved and shaped once dry.

Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
This block was nicely straight grained and split very well with an oversized cleaver acting as miniature froe. Splitting the rough block ensures the grain is fully aligned with the blade.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
It is common to saw the tsuka in half and then plane it flat, but for this small piece I was able to split it in half as well. This will give the glue a larger surface area for gripping.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Beginning to carve the omote side. The ura side is not carved until after this side is close to finished dimensions.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
For the final fitting, the tang is wiped with oil so that it will show up uneven points of contact with the wood. Scraping with curved kiridashi is a technique for refining and smoothing the inside.

Making Sokui (Rice Paste Glue)

Sokui is a simple wood glue made from rice that is traditionally used for joining wood from tsuka to sliding panel shoji. The all natural glue contains nothing but delicious Japanese rice and a little bit of extra water. One of the reasons rice glue was originally chosen for making tsuka is that it is non acidic, does not degrade either the steel or the wood over time, and does not retain moisture. Another is that, while quite strong, it is not stronger than the wood itself. This allows a scabbard or handle to be split open for cleaning or repair without damaging the wood.

A bite or two of cooked rice is placed on a board and worked with a bamboo or wooden wedge to break all the grains into pulp. As the rice is squeezed under the wedge it becomes like sticky dough. Once there are no pieces left, a few drops of water is worked in to bring the glue to the desired consistency. It should not be runny but should be thin enough to spread evenly on the parts to be joined.

Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Cooked Japanese short grain rice, the tastier the better. More than a small bite’s worth will take a long time to mix and produce far too much glue…unless you are making shoji!
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Mashing it together helps break up the grains, pulling it out under the wedge in small amounts will help crush the pieces into paste.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Once there are no pieces left at all, it is time to add a small amount of water to thin it a bit.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
The final consistency should be as thick as possible while still easy to spread in a thin layer. Too much water will weaken the joint and increase the drying time, too little makes it hard to spread thinly and evenly.

Gluing the Core

A thin layer of glue is spread on one or both tsuka parts, depending on the consistency of the glue. The two parts are tightly bound with a cord or leather strap and wedges further increase the pressure. Using a strap rather than clamps provides an even, non-marring pressure even when the block is not yet perfectly square and true.

This small tsuka will have an unusual ki-fuchi, a wooden accent in place of a fuchi. Pacific Yew is a relatively hard and dense wood with a beautiful rich orange colour and natural gloss. In this case, the accent will be attached to the tsuka and have the grain running vertically to add strength and stability, making it functionally more like a true fuchi rather than a floating tsuba.

Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Core parts ready for assembly, note that the glue layer is very thin.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Tightly bound with an even winding and pressure, then tension is increased with wooden wedges in certain areas.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
After drying 24 hours, the front of the block is leveled and trued using a granite slab.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Pacific Yew sawn to size and cleaned up on the granite slab. Double edged saw has both rip (top of photo) and crosscut teeth (bottom of photo).
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
A kiri is used to open several holes to rough out the nakago-ana. There are several different styles of kiri bit, this one is a three sided type forged from an expired file. Kiri give great control and can be used much more precisely than a standard modern drill bit.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Small coarse files are used to complete the nakago-ana in the ki-fuchi and the piece is cut to size.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
The piece is aligned and bound with the tang in place and then once stable, the tang is removed for drying.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Squaring up the block to the ki-fuchi. A saw file removes a lot of material quickly without deep scarring like a rasp, using a plane in this situation would be difficult because of the cross-grain of the Pacific Yew.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Nootka Cypress shims to reduce the strain on the harder Pacific Yew and provide some shock resistance.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Shims on all four sides, filed to fit the tang.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Drilling the mekugi-ana using a hand powered post drill. The location on the tang is chosen based on an estimate of best placement on the finished handle, and then the actual hole in the handle is placed based on the location of the hole in the tang. The opening in the tang will be enlarged and adjusted using a round file in the final fitting.

Shaping the Tsuka

Chisels, knives, rasps, and coarse files are used to turn the block of wood into a graceful handle shape and smooth the contours. This would be the final stage for a wooden handle or shirasaya, but this piece will be finished by wrapping over the core with samegawa. Starting from the profile of the seppa, the shape of the handle is carved at the fuchi and then carried back by stages, working from a squared taper to a rounded one. Extra wood is removed to make room for the wrapping to come.

Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Using a kiri to begin the mekugi-ana, it will be enlarged with a small round file.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Carving the profile down nearer to the finished outline.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Carving the ki-fuchi nearer to the finished shape, based on a tracing of the seppa.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Matching the front of the tsuka to the ki-fuchi.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Tapering the sides back towards the kashira.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Tapering the corners back towards the kashira.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
This would have been the look if the mount was to be a simple wooden kaiken, but this will become a small aikuchi mount.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Setting the depth for the wrapping with a coarse file and carving the core down to meet it.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
The tsuka growing out of its block of origin, not much more can be done while it is still attached.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Separating the tsuka from the remains of the block.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Tsukigata were originally designed to make room for the end knots to sit lower on wrapped handles, however they are often included on the omote side of unwrapped handles as well. My theory is that they serve as a reference point for registering the position of the handle and direction of the blade by feel.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
The Pacific Yew for the ki-kashira is cut roughly to shape and glued on to the tsuka core.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
The outline has been established, next the contours of the end are carved and smoothed.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
A subtle tribute to the yama-no-michi, it will become even more subtle in the finished design.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Smoothed out showing the grain. The ki-kashira is bookmatched with the ki-fuchi so the swirls in the grain mimic each other.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
The finished wood tsuka core. Steps remaining are to coat the Pacific Yew with 100% pure Tung oil and add the wrapping to the handle.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
A coat of 100% pure Tung oil brings out the natural glow and colour of the Pacific Yew. Like Walnut and Linseed, Tung oil penetrates the wood cells and then cures, sealing itself in and helping keep moisture out.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
A size comparison for scale. This is an antique wakizashi shirasaya tsuka (measuring a generous hand and a half) which is closer to the finished size of the whole kotanto and saya than to the tsuka itself!

Wrapping the Tsuka

An additional layer of strength, grip, durability, and embellishment is often added to the wooden tsuka using a rawhide wrap and leather or silk cord. Deer rawhide is sometimes used, but most often samegawa (ray skin) is seen under formal wraps or on its own. Rawhide is stiff and strong, and samegawa in particular has a good grip for the hand or for locking in place any cord that wraps over it.

Ordinarily black samegawa would be created by coating over the rawhide with urushi (natural laquer). In this case a tanned and dyed samegawa will be used for its beautiful appearance, texture, and glassy shine. A paper pattern is made to determine as near as possible the shape of the samegawa needed and then a piece is cut slightly oversize and trimmed down bit by bit. Because the leather is black and the wood very light, strips of dyed paper are glued in place under each of the areas where the samegawa will end. Once this is fully dry, the skin is carefully glued in place and bound with leather cord until dry.

Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Making and adjusting the paper pattern. Paper does not conform well to compound curves unless wet formed, so this is an approximation.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Shaving down thick areas of the skin from the back. Cutting the skin is a challenge as each node is like a bead of glass.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Dyed paper glued with sokui where the seams and edges of the samegawa will fall. Very reminiscent of sashimono nobori, samurai banners, somehow.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
After the skin is glued and fine adjustments are made to placing the seams and edges, it is wrapped tightly with a leather cord to dry.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Omote side with the finished black samegawa wrap.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Ura side, the samegawa meets along the centre, running through the mekugi-ana.

Making the Mekugi

The Japanese sword is unique in its handle engineering as well. The tsuka and nakago are shaped and fit together in such a way that the strength of a single bamboo peg holds the whole unit together and so that removal of the peg allows complete disassembly. This allows the blade to be easily removed for cleaning and sharpening and allows for replacement of the mounting without damaging the blade in any way. In addition to being inserted from the omote side, it is important to note that mekugi also have a correct orientation in the mekugi-ana. The part of the mekugi with the most dots is the outside of the bamboo plant and the strongest. It should be rotated towards the back of the handle, where the nakago places the most strain on the peg.

Because this is a tanto, and a small one at that, the peg need not be bamboo as with a sword. Horn, hardwood, and sometimes metal mekugi are found on antique tanto koshirae. In this case the deep red wood is drawing to mind the colour of an urushi laquer finish. The wood is shaved to a rough taper with a chisel and then smoothed with coarse and fine files as it is slowly adjusted to a final fit before being cut to length. Antler tip leaves a glossy burnished surface and the ends are sealed with 100% pure tung oil.

Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Creating the taper with chisel and coarse files.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Rounded and smoothed, then burnished with antler.
Island Blacksmith: Hand forged kotanto made from reclaimed and natural materials
Finished and ready to drive home for the final mounting.

The next step in the process is Carving the Saya, or scabbard.