About Japanese Tools


The essence of the Japanese woodworking tool is an incredibly sharp cutting edge which leaves the wood with a satin smooth finish. Mastering the use of fine Japanese woodworking tools requires a great deal of patience, and years of practice. Yet, the warmth of wood, the delicate balance of the tool, and the mirror finish of the edge makes it worth the effort.

The forging techniques used to make the tools are known to most people in connection with the samurai sword. These techniques involve the repeated folding and hammering out of steel, over and over again. This process imparts in the steel certain “toughness” (it is flexible, yet hard). Use of this process (rather than the simple addition of alloys to greatly increase carbon content) gives the tool an easily sharpened, long-lasting, and resilient (not brittle) edge.

The traditional Japanese forging techniques are complicated and take great skill and determination to master. Hence, there are tools of greatly varying quality on the market.



Basic information on Japanese saws:
Japanese saws cut with a pull stroke. Compared to a push stroke saw, less force is required to cut, and a cleaner cut is created because the saw blade is thinner than its Western counterpart. To make a smooth cut, hold the handle near the end and apply only slight pressure while pulling, but not while pushing. Applying too much pressure while pushing can cause the blade to snag and bend, and in the worse case scenario it can break. After use, saw teeth should be cleaned and wiped dry. Removing moisture and sap reduces rust and helps maintain a sharper blade.


Basic information on Japanese planes:
Traditional Japanese woodworkers depend on planes rather than sandpaper to create finished surfaces. Planed wood achieves a far smoother surface than those finished with sandpaper because the plane blade cuts all of the wood fibers at exactly the same level. Thinner and longer shavings leave smoother and flatter surfaces. Western planes cut when pushed, but Japanese planes cut when pulled, just like the saws.

A Japanese plane is in its purest form, simply a wooden block*1 and a blade (usually with a chipbreaker*2 also). It looks deceptively simple, but its adjustment is a delicate task and requires time and dedication. The effort is worth it and the pay off is immensely rewarding. Wood finished with a well-adjusted Japanese plane will be so smooth that the surface will actually show reflections like a mirror. For this to happen, the plane needs to be sharpened and precisely adjusted frequently.

*1 Plane block (dai): The body of a Japanese plane is made of solid wood. Usually oak is preferred. The blades are held securely by the grooves cut in the block and the tapering thickness of the blade, not by a wedge. The block needs to be adjusted so the blade will fit snugly, but not tightly. How much the blade protrudes from the sole can be adjusted by tapping on the blade or body of the plane with a hammer.

*2 Chip breakers: Many planes have a second blade called a chip breaker, which breaks the wood fibers immediately after they are cut to reduce tears. A single-blade plane can create a smoother surface than a plane with a chip breaker, but requires greater skill to be able to smooth the surface without tear-out. It is possible to reduce tearing without a chip breaker by raising the angle of the blade, but the finish will be rougher.


Basic information on Japanese chisels:
When katana (Japanese swords) were outlawed by the government at the beginning of the Meiji era (1868-1912), the skills of sword smiths were no longer in demand. Some sword smiths decided to use their skills to make chisels and plane blades. One of the skills was to make chisels by laminating hard steel to softer iron. The hard steel is for the sharpness of the cutting edge and the soft iron is for strength and flexibility. After the two metals are combined and shaped, the steel is hardened and tempered. The back of the blade is hollowed* so that flattening can be done faster. The same thing is done for plane blades. It is said that a blade cuts well when the flat distance between the hollow and the edge is minimal.

*Single hollow vs. multiple hollow: The back of a chisel has a hollow to make the flattening process easier by minimizing the area that needs to be flat. Whether a chisel comes with a single or multiple hollow, it will not have an effect on the cutting edge. A multiple hollow chisel has extra flats so it will be slightly easier to make straight cuts, particularly when paring past an edge. But because there are extra flats, it takes a bit more time to flatten the back. Some woodworkers like the multiple hollow style simply for its beautiful design.


Basic information on hammers:
Carpenters in Japan use several different hammers, each designed for a specific purpose, such as hammering nails, adjusting planes, and striking chisels. Unlike framing hammers, a traditional Japanese hammer does not have a nail puller, but is flat on one face and slightly curved (convex) on the other. To pull out nails, carpenters use a separate nail puller. The flat face of a hammer is used for most of the hammering and the curved side called a “kigoroshi-men” is used for the last blow. The kigoroshi-men is designed to drive a nail into the wood without damaging the surrounding surface. Also, furniture makers use the kigoroshi-men to temporarily compress a tenon to fit it into its mortise. After assembly, the wood gradually expands to its original size for a tight fit. In this process the kigoroshi-men can dent the wood without tearing its fibers, but the edges of the flat face of the hammer will tear the fiber and the wood will not expand even if water is applied.


Japanese square (sashigane): It is an L-shaped tool used to draw layouts, measure lengths, and calculate angles. Traditional Japanese carpenters used squares for practically everything related to layouts and calculations when they had to build houses and complex buildings such as temples. The knowledge of squares evolved to a special skill called “kiku-jutsu,” and its complexity makes it one of the hardest, but most important, skills used in Japanese architecture. In Japan there is even an old saying expressing the sorrow of a carpenter struggling to master a square—“Like a sparrow crying on the corner of the eaves, so does the carpenter cry over the corners”. But although a Japanese square is designed to meet the most rigid demands of professional carpenters, its practicality can be enjoyed regardless of your woodworking style. It is definitely worth your time to understand at least the basics of a Japanese square.

A Japanese square has measurements on both front and back. When the long blade is standing vertical and the short one is facing right, you are looking at the front. There are many different markings on a square, depending on the measuring system you are using, but all Japanese squares have a standard scale on the front and one based on the square root of 2, called “kakume,” on the back. There is also a circle circumference scale called “marume” on the back.

Hida Tool & Hardware Co., Inc. © 2019