The tang and handle of a classical tanto are constructed in a manner that requires only a single bamboo peg to hold the entire knife assembly together. In addition to the sense of beautiful simplicity, this design allows the knife to be taken apart for cleaning, polishing, or sharpening work.
Carving and fitting the inside of this type of handle is not as daunting as it seems and can be done successfully through a careful and deliberate approach based on the study of historical examples. This article will attempt to provide a closer look at some of the elusive details of the geometry and construction of the core of a tanto handle.
The tools used for creating this style of handle are quite simple, the work can be done with only a handsaw, a saya-nomi chisel (鞘鑿), and a kiridashi knife. A wood block kanna plane is also helpful for leveling the inside and shaping the outside.
The core of a handle and scabbard are traditionally carved from hou-no-ki (Japanese Bigleaf Magnolia) due to its non-acidic, moisture-stable, and shock absorbing nature. The example below was carved from local Nootka Cypress which shares similar grain density, moisture stability, and shock absorbing properties.
The glue for rejoining the halves is rice paste glue (sokui) which is non-acidic and does not gum up cutting tools when working. The simple clamping system uses a leather strap and scrap wedges of softwood to tension the halves while the glue dries.
Proper geometry of the tang is crucial to making a properly functioning nihonto style takedown handle. The tang must taper in thickness and width from the machi (blade shoulders) along the spine, and the edge side should be an even thickness of about 2mm all the way from the machi to the tip of the tang. The surface should be relatively smooth and even, with no major bulges or dips, and it goes without saying that the blade must always be hardened and tempered before starting work on any fittings. Read more about tanto geometry here: Classical Tanto Geometry Archives
The blade in the example below was forged from a reclaimed file and will have a forged final finish in the Tools for Satoyama style. If it were to be polished, the final geometry and dimensions must be set first, but the final polish and sharpening are done after the handle has been made.
If it were to have a habaki and seppa, these would also be made before fitting the tsuba (guard) and carving the handle, to account for the difference in length. I don’t recommend skipping the habaki in a large knife’s construction as it is difficult to achieve and maintain a good fit with the saya. The blade here is just under 7.5″ long, the tang about 4″, and the spine at the munemachi is about 5mm thick.
The knife has two sides with unique names, the omote and the ura. The omote is the “public side” and the ura is the “private side”. When worn with the edge up and the handle towards the right hand, the side facing outwards is the omote and the side facing against the body is the ura.
The tang does not sit halfway into each half of the handle, the split line is slightly to the ura side making the omote block slightly larger. This offset only occurs on the edge of the tang, the spine is evenly split. The purpose for this is to place the stress along the edge against wood rather than against a glued joint. This is far easier to understand than to explain in words, see below.
Splitting the Block
The grain should run as straight along the handle as possible to give strength to the handle. Also, for the sake of stability, many historical examples run the growth rings diagonally across between omote and ura when viewed from the ends.
If the block is large enough, one need not worry about making the split slightly diagonal, simply split down the centre and trim off the excess later on. A sharp handsaw will split fairly straight and a kanna plane can be used to true up any wobbles or tooth marks. The halves must fit together flat and true with no gaps or rounding. It is wise to mark the blocks so there will be no mistake in placing them back together the same way again whilst working.
Carving the Omote
The omote side is carved first and has the deeper carving work to be done on it. The blade and fittings are placed squarely and snugly against the front of the block and the tang traced. Then a kiridashi is used to cut a shallow line around the exact location of the edges of the tang. Carving up to the scored line, the mune is cut and then then working across the edge of the tang is cut.
The depth of the spine side should be half and the edge side should be flush but not inset at all. Careful carving will ensure the tang is contacting wood all around without any gaps. Sliding the tang into place will burnish any high spots enough that they can be seen when viewed obliquely into a North window. Working slowly and checking often will save wood and time.
Carving the Ura
The ura side is carved after the omote is fairly close to final dimensions, though often a small amount of readjustment is necessary once both are carved. Aligning the tang for tracing is more difficult this time around and care should be exercised. Holding the blocks together and marking where the omote side opening is located is helpful. This time the kiridashi cut is only made along the spine as the edge side will not be notched in at all.
Carving from the mune and working across to the flush edge side, frequent checking and restraint are required. When the dimensions are close, testing with both halves held together may reveal additional areas for adjustment. The goal is for all surfaces to be smooth and the tang to seat snugly but still removable.
Rejoining the Halves
Rice paste glue (sokui) is used to join the halves together as it is non-acidic and kind to wood carving tools when dry. A paste of mashed rice and a few drops of water is applied thinly to both halves and placed together lightly and reopened to check the contact points. If any area is missing sokui, more can be added or redistributed and if any is pushed out into the tang area it must be fully removed.
The glued halves are joined and then clamped with a leather strong lace. Winding too far apart will place a diagonal pull on the blocks and they may slip. Thin wedges of softwood are placed under the wrap to further tighten and prevent slipping. The glue is allowed to dry for 24 hours before unwrapping.
Carving the Exterior
Once the blocks are dried, the exterior is carved to shape using chisels, a kanna plane, and kiridashi knives. Tracing the location of the tang on the sides as well as the fittings on the end gives reference points for planning the handle shape.
Often the first shaping step is to use a plane to square the block up to the blade if it is angled or off-centre. After this, a kiridashi or chisel is used to carve the outline of the handle cross section first at the end and then the rest of the block is carved down to meet it.