The Varieties of Japanese Chisels Part 1 – The Main Categories

“Electrical tools are consumables; our tools are part of our bodies. Do not treat tools as just things. It is a mistake to think of tools as just your own. The shape of every tool was not decided recently. Over a long, long time it was decided that this form would be most useful.”

Nishioka Tsunekazu, Temple Carpenter in charge of the Horyuji and Yakshushiji Temple Restorations
Ichimatsu Tsukinomi – Kiyotada

There are many varieties of Japanese chisels, and most people, including Japanese, are confused by the meanings of their names, and their various applications. I am not an historian or archaeologist, but I have been using them for over 40 years both professionally and for the fun of it and like to flatter myself I know a bit about them. Perhaps this and future posts will help de-muddle a little of the confusion.

In this first post in the series I will explain the components of Japanese woodworking chisels, and the two main categories. In later posts I will explain the various types of chisels included in these categories in some detail. But let’s begin with some language matters.

Terminology and Translation

Where a suitable English word is available, I will use them, but for the most part, I will employ the Japanese terms converted from Kanji (Chinese pictogram characters) and Hiragana (phonetic Japanese characters) to the Roman letters used in most English-speaking nations.

The word for “chisel” in Japanese is “nomi” (鑿). The Chinese character used to write this word is complicated, so it is normally converted to the phonetic hiragana letters as “のみ.” You will notice that nomi is part of every chisel’s name, so I will use it too.

Structure and Components of Japanese Chisels

The design of Japanese chisels is a little more complicated than their Western counterparts, but the basic components are generally the same. So let us examine the similarities and differences.

Blade and Neck Construction

42mm Hidarino Ichihiro Oirenomi – Face View

Traditional Japanese chisels have laminated blades with a body, neck and tang made of iron or very low-carbon steel that remains relatively soft during heat treatment. A layer of high-carbon steel is laminated to this iron body at the blade to form the cutting edge. During the quenching process, this layer becomes very hard, typically 62~67 Rc versus the typical hardness of 58~60 Rc found in Western chisels. The two layers are most visible at the bevel. This additional hardness has both advantages and disadvantages, depending on the crystalline structure of the steel after heat-treating and the skill with which the tool is used and maintained.

In the case of hand-forged (teuchi 手打) blades, this lamination is made by forge- welding the two types of metal over several heats using hammer, tongs, and anvil.

European chisels were also fabricated using this technique before the advent of mass-produced inexpensive steel. Unfortunately, this once-universal excellent technique has been all but forgotten outside of Japan.

Materials & Process

The best professional-grade chisels are made of high-quality iron and the purest plain high-carbon steel. These ancient metals are difficult to work, being very sensitive to temperature and thermal shock and tending to warp and crack badly in less than experienced hands. Many alloys and processes have been developed over the last 60 years to make tool production more profitable using unskilled labor, but for simple cutting ability and ease of sharpening, nothing rivals this combination.

The blacksmithing process involves forge-welding the two types of metal to form a laminated blade, then shaping and hand-forging over multiple heats, followed by carbon soaking and annealing, a coating of secret mud sauce after which the blade is heated to just the right temparature and subject to multiple quenches followed by multiple temperings. The process varies from blacksmith to blacksmith with each craftsman using different formulas and procedures. Of course, warpage must be compensated for by shaping a curve in the blade that straightens out during heat treatment. Learning these skills takes years of hands-on training from a young age under the eye of a master, and decades of dedication to quality. It certainly cannot be accomplished in a mass-production situation, much less by Chinese peasants or even CNC robots.

Mass-produced consumer-grade Japanese chisel are made of pre-laminated strip steel manufactured in steel mills by either cold-rolling or hot-rolling a layer of high-carbon steel to a layer of mild-steel. This material, called ” rikizai” (利器材)or ” fukugozai” (複合材)was originally developed for mass-producing inexpensive kitchen knives as a labour-saving material to reduce manufacturing costs.

Blades made from rikizai typically perform adequately for most consumers, but many professionals seek the higher performance of so-called ” fine-grain” steel’s smaller and more uniformly-distributed carbides found in hand-forged, expertly heat-treated blades. Those who develop the skills necessary to discern the difference between such professional-grade and consumer-grade blades, can never be satisfied with the inferior tool.

Hollow-Grind

42mm Hidarino Ichihiro Oirenomi – Back View

Japanese chisel blades have a hollow-ground back (the so-called ” flat” on Western chisels) which makes the harder steel easier to sharpen and keep flat. Without this hollow-ground ura feature you would find sharpening a chisel blade of similar hardness time consuming and almost impossible to keep flat over many sharpenings.

Tang and Ferrule

Japanese chisels appears at first glance to be socket chisels, but they are definitely tang chisels. The handle incorporates a steel ferrule shaped like a truncated cone and called the “ kuchigane” (口金) which translates to “mouth metal.”

The Four Components of a Tatakinomi: Blade, Handle, Kuchigane, Crown

This component receives the reaction forces of hammer impacts from the blade’s shoulders converting these thrust forces acting in the handle’s long axis to compression forces acting on the handle’s end thereby preventing splitting and locking the tang tightly into the handle. It is a subtle but clever and effective design that combines the best features of both tang chisels and socket chisels without any of the downsides.

The Crown

The “Keima” Chess Piece

Chisels intended to be struck with a steel hammer have a sturdy steel hoop called a ” katsura” installed at the handle’s end to prevent the wood from splitting. The characters used for this word include 冠, pronounced “kan” or “ kanmuri” meaning “crown” or 桂 meaning Judas Tree or “ knight” (桂馬)as in the chess piece. The word Katsura can also mean “ wig” a term that does not quite work in this case because chisel handles are as bald as I am.

I have the bad habit of anthropomorphising my tools. They hate that, so to avoid giving further offence (they sometimes bite, donchano), I prefer to translate katsura as the more elegant word “crown” instead of the more constrictive word “hoop” or follically-challenged word “wig.”

Just in case you aren’t entirely confused, please note that this same steel hoop is also called a ”sagariwa” (下り輪) which translates to ”drop hoop, ” a term that is accurately descriptive because, over many years of hammer blows, the handle gradually shortens and the hoop “drops,” shifting its position down the handle.

The crown is made of relatively soft but still strong mild steel. In use, it may occasionally be struck by a steel hammer. This choice of material is not based on economics or convenience but on the practical reality that the face of a steel hammer impacting the edge of a hardened steel hoop would get dinged and even deform after enough hits.

But this creates another problem, namely that the crown may eventually become deformed by hammer strikes unless preventative measures are taken. This is not a trivial cosmetic matter because the hoop’s edge may deform to the point it curls back inside itself. Then, if the user continues to beat on the chisel, the hoop will gouge and eventually split the handle.

Damaged Crown and Handle

The best way to avoid this grief is to use a hammer with a flat instead of convex face and to properly setup the chisel when new. For instructions on doing this, please see my earlier post about Setting-up Japanese Chisels.

Another downside to the crown and steel hammer arrangement is that the end of Japanese tatakinoni are far from smooth and can be uncomfortable to use when paring. The solution to this is three-fold. First, setup the crown properly and chamfer and smooth its edges. Second, avoid hitting the crown with hammer so it doesn’t become rough and gnarly. And finally, use a tsukinomi chisel for paring. Life is good.

Handle Materials

Chisel handles can be made of a variety of woods, but strong hardwoods such as oak are commonly fitted to chisels designed to be motivated with hammers.

Chisels not intended to be struck with a hammer can be fitted with more brittle but decorative wooden handles such as ebony or rosewood.

The Two Categories: Tatakinomi and Tsukinomi

Tsukinomi

There are two primary categories of Japanese chisels. I think these same categories apply to other traditions, but in the difference is especially clear-cut in Japan.

The first category is the “tsukinomi “ (突き鑿). Tsuki means “to push,” so tsukinomi refers to push, or paring, chisels. Standard widths range from 1.5mm to 48mm. Handle lengths and materials vary with the type of tsukinomi, the intended purpose, and personal preferences.

30mm Mitsuura Tsukinomi – Sukezane

Tsukinomi are pushed by hand and sometimes by shoulder in the case of the large ootsukinomi, known in the West as “slicks.” Most tsukinomi have relatively longer, more slender and elegant necks. They incorporate the same kuchigane ferrule at the blade end of the handle, but do not have a steel crown hoop reinforcing the opposite end.

Standard Ootsukinomi Set: 24mm and 48mm
Paring the Cheeks of a Beam Splice Using an Ootsukinomi
Paring a Rafter Post Seat Using an Ootsukinomi

By definition these chisels are not intended to ever be struck with a hammer. Even if the handle does not split, their more slender necks will not endure impact forces gracefully. More often than not they are used to clean and pare to final tolerances joints cut using other chisels.

Tatakinomi

The second main category of Japanese chisel is called the “tatakinomi” (叩き鑿)meaning “striking chisel.” This is the style of Japanese chisel best known outside Japan. These chisels are stronger and tougher than tsukinomi and are intended to be struck with a steel hammer.

42mm Atsunomi Ura – Sukemaru (300mm (11.8″) Overall Length)

Wooden mallets are not typically used with Japanese chisels. The logic for this practice is simple: A steel hammer is the smallest, lightest, and most energy-efficient way to motivate a chisel. The physics of this are self-evident. Accordingly, the logic behind the tatakinomi design is that, since it must efficiently remove lots of wood, and a steel hammer is the most efficient way to motivate a chisel, the tatakinomi’s handle must be designed and made strong enough to endure being struck by a steel hammer from sunrise to sunset. A simple calculus.

250 Monme Kosaburo Gennou (938gm, 330z) Black Persimmon Handle

By contrast, the Western tradition of using chisels with inherently fragile handles requiring users to obsessively baby them with relatively soft, energy-wasting, un-aerodynamic, big-ass mallets is illogical and inefficient. But to each his own.

Some people stubbornly insist on using mallets even to strike their Japanese tatakinomi. This reminds me of the country bumpkin that bought a newfangled chainsaw from a hardware store in town to cut firewood only to bring it back the next day complaining it was slower and more work than his old axe and handsaw. The puzzled hardware store owner checked the fuel and spark plug, but found no obvious problems. With a perplexed look he yanked the starter rope. The chainsaw’s motor started right up with a roar and a cloud of smoke. The shocked customer almost jumped out of his overalls in wide-eyed surprise, screeching “ what the hell’s that racket!?!”

According to the Takenaka Carpentry Tools Museum located in Kobe, there are 9 varieties of tatakinomi. https://www.dougukan.jp/tools/20

In Part 2 of this series I would like to describe some of these beginning with the “Mentori Oiirenomi.”

YMHOS

YMHOS

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9 thoughts on “The Varieties of Japanese Chisels Part 1 – The Main Categories

  1. Thank you for doing this! I did a turn as a Canadian diplomat back in the 80s and picked up quite a few tools on my various trips to Japan, mostly garden variety from Tokyo Hands although I did get a couple from local makers in Osaka. I look forward to future articles!

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      1. I have a 1/4″ dovetail chisel made by Teruo Miyanaga. I would be interested to know if you are aware of him or have any insight into the merits of his craftsmanship with forging blue steel chisels?

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      2. Ron, Thanks for stopping by.

        I am familiar with the name. He is a Miki blacksmith. Not aware he made chisels from Aogami steel. He has a good reputation among some, but I have not used his tools.

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  2. Hi Stan Thanks for providing the great information as I have not found it to be readily available. Looking forward to the next installment. Think I have worked with the guy who bought the chainsaw.
    Regards
    Randy

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  3. Kind of late to the party but enjoying all the threads. Some questions: I’ve seen the term “hidari” here and in other places. What does that mean? The crown on the Sukemaru nomi does not look as robust as those on others. Should one draw any conclusions from looks alone?

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    1. Dmikulec: Thanks for reading the blog and for your excellent comment.

      The Japanese word “Hidari” means “left” as in left hand. It’s use in this way is unfortunate in that it is necessitated because of legal theft and lies. Ichihiro (Yamazaki-san) is not the only famous blacksmith to turn to this rebranding.

      What happens is someone copies the unregistered brand name and stamp of a famous product, typically one that has been used properly for decades and even centuries in some cases, then registers it. They then mark inferior products with the brand and deceitfully sell them as originals. Dishonest but legal.

      The original owner of the brand/ trademark must either abandon the brand/ trademark or modify it to avoid legal problems with the thief. One way is to use a mirror version of the brand, in Yamazaki-san’s case, the characters 市弘 (written with the first character located above the other). Same characters in the same location but mirrored. A character written this way is said to be written “left” or “hidari.”

      Interestingly, in the case of simple, very common characters like these, most people can read them written left handed without a problem.

      Yamazaki-san also registered another brand name to deal with this despicable liar. He added a crescent moon mark in front of his normal brand. This is called “Tsuki Ichihiro” with tsuki meaning moon.

      Sadly, the theft and fraudulent use of brand names and trademarks has a truly ancient history in Japan. Swords are an excellent example. There are many Ichihiro and Kiyotada brand chisels and planes sold on the internet ( especially auctions) and even in Kezuroukai in Japan that are pure-d fakes. Caveat emptor.

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