Japanese carpentry

Japanese carpentry is distinguished by its advanced joinery and its finely-planed wood surfaces. Japanese carpenters use a different set of tools and techniques from European carpenters. They also use different conventions of marking out.

Tools

These are the tools that are most commonly used:

Japanese saw ("nokogiri" 鋸), which cuts on the pull stroke, rather than the European style push stroke. This allows the blades to be quite thin in comparison to the Western saw. There are two main kinds of cutting teeth on Japanese saws: rip (yoko noko-giri)and crosscut (tate-noko-giri). The rip and crosscut are combined in one blade, known as a "ryoba" (lit. "dual edge":; 両刃). The rip and crosscut patterns are also made in single-edged saws, "kataha nokogiri" 片刃, both with stiffening back pieces and without. The stiff-backed saws, known as "douzuki"　（lit. "with guide"; 導付き) are typically used in cutting fine joinery. There are many other types of Japanese saws as well: "osae-biki" 押さえ引き鋸 (lit. "press-cut saw"), used for flush-cutting pegs to a surface without marring the surface. The saw teeth have no set to one or both sides to accomplish this feat. There is the "azebiki" (lit. ridge saw; 畔挽き), which has cutting both rip and crosscut teeth, and is short and rounded in profile. It is used for sawing in confined areas and starting cuts in the middle of surfaces. There are many other types and sub-types of saw. Most saws sold in the West are mass produced items with induction-hardened teeth and relatively cheap replaceable blades. The handmade forged saws are very laborious to make and involve more manufacturing steps in the forging to complete than planes of chisels.

Japanese plane ("kanna" 鉋), which is a wooden block, or "dai" (台) containing a laminated blade, sub-blade, and securing pin. This is similar in respects to the archaic type of European wooden plane, in which the blade is fixed in place by tapping down upon a wooden wedge. In the Japanese plane, the blade is fixed in position primarily by the confines of the plane's throat opening. Unlike a western plane, the support bed for the blade is not a flat surface in a Japanese plane - rather it is convex. The blade itself is tapered both in thickness and in width so as to wedge tightly into the dai when tapped down into place. Japanese planes are operated by pulling rather than pushing, and much work is done in the seated position or alongside a planing beam.

Japanese chisel ("nomi" 鑿). These come in a larger variety of types and gradations of than in Western chisels. There are bench chisels, paring chisels, striking chisels ,heavy timber chisels and slicks, and a myriad of specialized chisels made. Like the planes, the blades are of laminated hard steel/soft steel construction. Bevel angle varies from 20˚ to 35˚ typically, with mortising and heavy chisels featuring steep angles, and paring chisels having shallower angles. It is common in Japan to work with softwoods, so many chisels are made with that in mind, and require the bevels be steepened if employed for harder woods.

The blades used in the Japanese chisel and the Japanese plane are based on similar constructive principles as the "katana" or Japanese sword. A thin piece of extremely hard blade metal called "ha-gane" 鋼 (lit. "edge metal") is forge-welded to a softer piece of metal called "ji-gane" "(lit. "base metal" 地金)". The function of the softer base metal is to absorb shock, and to protect the more brittle "ha-gane" from breaking. This technology allows for the use of steels in the "hagane" which are harder than in use in Western chisels - typically Rockwell 62 and up.

There are many types of steel used for the "ha-gane" of Japanese planes and chisels:

-White steel, "shiro-gane"; a nearly pure steel that takes a very keen edge and resharpens easily. There are several types of white steel, #1 and #2 being the most common.

-Blue Steel, "ao-gane"; a steel with alloyed elements such as molybdenum to enhance the durability of the edge. This steel is a little more difficult to sharpen than the white, and does not take quite as keen an edge, but is more durable in use. The common blue steels used are #1, #2, and "Super-Blue"

-"Tama-hagane"; this steel derives from the smelting of a special iron-rich river sand and is normally reserved for use in sword-making, however some does find use in saws, chisels and planes.

-"Togo-Reigo": this steel was produced by the Andrews Company of Sheffield England in the 1920's and some found its way to Japan where it has been used for making plane blades

-Swedish Steel

The blades of both planes and chisels are distinguished by the scallop, "ura" in their flat side. This scallop has a number of functions. The primary function is that it ensures a high degree of flatness when sharpening, in that when the flat side is polished it cannot rock or develop a curve because it is only contacting the stone on either side of its width. This then improves the precision with which cuts can be made by the chisel, and in the case of planes ensures smooth contact with the wedge and therefore even support across the full width of its blade. The hollow also greatly reduces the amount of metal needed to be removed to achieve flatness on the back of the blade, which shortens initial set-up considerably. Secondly, in the case of chisels, it reduces the frictional resistance as the chisel is driven into or extracted from the wood. Thirdly, the interaction of the leading edge of the hollow with the edge of the blade is a changing relationship as the tool is re-sharpened. As the edge is sharpened down to the rim of the hollow, the edge can then be 'tapped-out' ("ura-dashi"), a process where a pointed hammer is used to depress the" ha-gane" downward slightly along the bevel of the blade. When the blade's back is re-flattened after "ura-dashi", the hollow is re-established; thus the hollow acts as a sort of gauge for sharpening as a means of prolonging the life of the thin piece of cutting steel as long as possible. This in turn tends to keep the geometry of the blade consistent over time,which keeps it fitting the "dai" over time.

Japanese carpenters known as "miyadaiku" are remarkable for their use of elaborate wooden joints. Japanese temples built according to these principles are among the world's longest surviving wooden structures. Teahouse and residential carpenters known as "sukiya-daiku" are famed for their delicate aesthetic constructions using a rustic materials. Furniture makers are known as "sashimono-shi", and interior finishing carpenters, who build "shoji" and "ranma", are termed "tateguya-shi".

Vise

The traditional Japanese vise was a wedge of wood tied to a post with a coil of rope. The wood was inserted under the wedge and the wedge hammered down.

Vises of any sort are used far less in traditional Japanese carpentry than would be the case for equivalent tasks in the traditional crafts of the West. Many tasks in Japanese carpentry associated with building, involve very large pieces of timber, and in general the weight of the timber and of the carpenter are used to stabilize the piece on which the carpenter is working. For this reason the carpenter's horses used in Japan are much lower than their Western counterparts, and carpenters must always position themselves over their work.Much of the work on smaller pieces of material can be done in the seated position, and relies on the fact that the saws and planes both cut on the pull stroke, enabling stabilization of the work using the body or shooting board.

ee also

* Japanese architecture
* Japanese handicrafts
* Housing in Japan discusses traditional and modern houses and their building materials.

References

External links

* [http://www.thesakebox.com/woodcrafts.html Chidorigoushi Japanese Lattice Screens & Puzzles] examples of traditional Japanese lattice, called Chidorigoushi (literally translated to Hounds-tooth check), that are found in numerous aspects of Japanese life. Wooden pieces are carved with grooves that allow them to fit together perfectly in a lattice without using glue or nails.
* [http://www.rothteien.com/topics/carpentry.htm Sukiya Living Magazine] publishes articles about Japanese architecture and Japanese carpentry
* [http://www.dougukan.jp/archive/eng/index.html Takenaka carpentry museum] in Kobe. Contains extensive material on the history of Japanese carpentry in sub pages.