The Varieties of Japanese Chisels Part 2 – The Mentori Oiirenomi (面取追入鑿)

42mm Hidarino Ichihihiro Mentori Oirenomi

The Oiirenomi (pr0nounced Oh-ee-reh-no-me) is the most common variety of Japanese woodworking chisel, and the style best known both inside and outside Japan. There are several types of oiirenomi. In this post we will look at the most popular type of oirenomi called the ”mentori oirenomi” ( 面取り追入鑿) meaning ” beveled” oirenomi.

DESCRIPTION

As mentioned in my previous post in this series, nomi means ” chisel, ” but the term ”oiire” 追入れ” is not so straightforward. It is composed of two Chinese characters: ”Oi” 追いmeaning ”to chase” or ” to follow,” and ”ire” 入れ meaning ” insert” or ”place in.” I am uncertain of the origin of this word, but some hints of the original meaning may perhaps be deduced from the characters.

As the name suggests, this chisel’s face is beveled at both sides making it lighter and better able to get into tight locations than the older-style kakuuchi, which we will examine in a future post.

I think most people agree that the two bevels moving up the blade, curving around the shoulder, and feathering into the neck give this chisel a sculptural, elegant appearance. The bevels do sacrifice some stiffness and authority compared to the kakuuchi style, but clearly, these compromises are acceptable to most consumers.

APPLICATIONS

A member of the tatakinomi family, it is designed to be struck with a steel hammer and has a hoop (called a “katsura” in Japanese which means “crown”) on the handle’s end to prevent splitting.

There are larger types of tatakinomi called atsunomi better suited than the oiirenomi to heavy cutting and wasting wood in applications such as timber frame joints, and most of those share the same mentori bevel detail, but oiirenomi are better suited to lighter tasks such as furniture work and interior installation work the same as Western bench or butt chisels.

Oiirenomi in general and mentori oiirenomi especially are light-weight, relatively inexpensive, and handy to use. All woodworkers in Japan own at least a few of these. They are sold separately but 10 piece sets are the most common arrangement.

YMHOS

© 2019 Stanley Covington All Rights Reserved

Please share your insight or comments in the section below. If you have questions or would like to learn more about our tools, please use the contact form located directly below.

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

© 2019 Stanley Covington All Rights Reserved

Please share your insight or comments in the section below. If you have questions or would like to learn more about our tools, please use the contact form located directly below.

The Essential Oilpot

If set up and maintained properly, the blades of quality chisels and planes will endure many decades of hard daily use. Maintenance is the hard part. This blog is about a tool that will not only make the chore of constant maintenance easier and more efficient, but will also make your other tools work better.

It is a sad truth that the blades of woodworking tools often receive more damage while they are waiting to be used than when they are actually being used.  Thankfully, corrosion of the sort that creates microscopic pits at the cutting edge can be easily avoided with common-sense solutions.

When not in use, store your chisels and planes where they will be protected from dust and large temperature swings. And oil your blades after every use to keep away oxygen, moisture, and chemicals that might make your expensive blades “turn red and go away.” I suggest you plan ahead to make it as easy as possible to apply good oil to your blades. An oilpot, or aburatsubo (油壺)as it is called in Japan, is a very useful, inexpensive, easily made, and time-proven tool for this purpose.

But oil pots are not just for the important job of keeping away corrosion. An oilpot close at hand will help to minimize the friction your chisels, saws, planes, and knives generate when cutting wood. The most striking benefit of this is that you won’t need to expend as much energy when working wood and your apparent strength and endurance will increase.  Perhaps more importantly, the wood being cut will be less able to deflect your tool’s blade away from the intended line of cut, increasing the precision of your work.

Besides chisels, planes and knives, the oilpot can be used to lubricate drill bits and augers.

You only need to look back in history a little way to see that these benefits are well established.

We know from the archaeological record that tallow, just rendered animal fat, was placed in grease pots and used as a tool lubricant in Europe from medieval times right up until petroleum products became widely available. It was also used in the Americas until the same time. Vegetable oil was used in Asia, and probably in Europe as well. I am told that the black crust found on many antique plane bodies (wood planes not aeroplanes) is oxidized and hardened tallow combined with dirt.

Indeed, I can recall my father, uncles, and grandfather using sticks of caning wax (a petroleum product) for the exact same purpose when I was a child, and before that my English ancestors probably used beeswax and tallow candle stubs. I haven’t tried soft tallow as a lubricant and probably never will since rancid fat has even less appeal to me than rancid vegetable oil, but the method I will describe in this post is a serious improvement over the ancient methods, in my opinion.

In Japan, an oilpot is made by cutting a joint of well-dried bamboo into a cup 3 to 4 inches deep. If you do not have bamboo where you live, a hollowed-out piece of close-grained barrel-making wood like White Oak, or a plastic mug, or even a segment of capped PVC pipe will work just as well. The important thing is the container not be made of metal, glass or ceramic or any other material approaching the hardness of a chisel blade.

Shape the cup so the bottom is very stable. Some people scallop the bottom so it essential rests on four or five spots at the perimeter. And a piece of sandpaper glued to the bottom will prevent your planes from dragging the oilpot around when pass their soles over the wick.

If you use bamboo or wood, prime and paint the inside of the cup, and underside of the foot, with a high-solids urethane or polyurethane paint. I used a natural urethane extracted from the cashew tree called “Cashew” on the bamboo joint in these photos. The gaudy orange color makes it easy to differentiate my oilpot from others on a jobsite

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Line the inside of the cup with an unbroken sheet of aluminum foil to prevent the oil from soaking through. The paint alone will slow down the oil’s movement through the wood’s fibers, but sure as hogs are made of bacon, without a reliable liner of some sort, it will eventually seep out making a mess.

Next you will need clean, white, cotton T-shirt fabric. Used clothing is fine. White because you want to be able to tell how dirty the fabric is at any time. T-shirt fabric because it sheds the least fibers. Clean because pixies hate it. If you don’t believe me, just ask them.

Roll it up very tightly, and bind it with string or thread. It will take several tries to judge just the right amount of fabric. You should be able to force this dense cloth wick tightly into the cup with  ¼” to ½” projecting above the lip. It must be a tight fit to prevent the wick from falling or pulling out accidently. Then, soak the cloth with your favorite lubricant and you’ll be ready to rock-n’-roll like Zeppelin. It will take some time for the oil to saturate the dense wick, so be patient.

In Japan, I was told to use vegetable oil and change the wick when it became rancid.  But I recommend you save yourself some trouble and at least one stinky wick and use a non-organic oil from the start.

Some people prefer straight mineral oil or scented furniture oil, which is just scented mineral oil. The lemony smell is nice. But carefully avoid any furniture polishes or oils that contain silicon because these will weaken glue bonds.

Some people prefer camellia oil, but be aware that the so-called camellia oil available commercially for rust protection is actually just mineral oil with a bit of yellow dye and some fragrance added, sold at ridiculously high price tag, much like commercial furniture oil. Caveat emptor, baby. But in truth, mineral oil is not only cheaper (sold as lubricant laxative in pharmacies), but performs better than genuine camellia oil because it will not become rancid and gummy.

While it sounds strange, the best lubricant in my experience is a lightweight, light-colored synthetic motor oil such as 5W Mobile 1. I have tried regular motor oil too, but the synthetic variety smells better, lasts longer and seems to perform better.

Store your oil pot in a metal or plastic container with a lid when not in use to prevent abrasive dirt from contaminating it. Some people make a container from a segment of PVC pipe with a flat end cap glued on to make the bottom and domed one left lose as a lid. Place some newspaper in the bottom of your container to absorb oil and stop the rattling noise.

Even a plastic bag will do until you find something better.

When you are cutting a mortise with your chisel, make it a habit to occasionally jab the cutting edge of your chisel into the oil pot, and even wipe the sides and ura (flat) on the wick to lubricate the blade. You will be pleasantly surprised to find that this bit of oil will make your chisel work not only go faster, but more precisely and with cleaner results. The oil will not weaken glue bonds.

Likewise, when using either a metal-bodied or wooden bodied plane, occasionally swipe its sole over the oil pot. This will greatly reduce friction and give you more control. But if you value your public dignity, be forewarned that the first few cuts after doing this will make you smile like a lunatic.

The same benefits of reduced friction and increased precision can be found in the case of handsaws too, although the difference may not be as noticeable.

Before you store your tools away for the day, a quick bit of oil from your ever-present oil pot will prevent rust and frustrate corrosive pixies.

During use, the cloth will naturally become frazzled and covered with sawdust and wood chips, and will discolor accordingly. No problemo.

If you drop the oilpot and it hits the ground, heaven forbid, Murphy’s Law of Buttered Toast dictates it will land oily-cloth down contaminating it with abrasive grit. If ignored, frikin Murphy will smugly use your oilpot to damage your tools and ruin your work. But never fear: If you simply brush the cloth vigorously with a steel-wire brush, sawdust, wood chips, dust and grit are easily removed.

Of course you always have a steel-wire brush close at hand to remove embedded grit from boards before planing them, right?

When necessary, you can re-roll or replace the cloth wick to expose a clean surface. As the cloth wears and stops projecting from the oilpot’s mouth, remove the wick and place some clean rags in the bottom to elevate it.

The oilpot is an ancient, dirt-cheap tool you will find to be a invaluable addition to your woodworking tool kit.

YMHOS

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Welcome to the C&S Tools Blog!

In this post I will introduce this blog’s purpose, my qualifications and motivations for writing it, and a description of the sort of subjects that will be posted.

It’s purpose is simply to share sound information regarding woodworking techniques, woodworking hand tools and construction work with an emphasis on Japanese hand tools and techniques

Although woodworking and construction are universal human activity, Japan has unique history and traditions and has developed techniques many find interesting. Indeed, most Japanese woodworking hand tools are different in some ways from their Western counterparts, and must be setup, maintained and used differently.

Unfortunately there is a lot of blather on the internet and even in print on these subjects that pound for pound is valuable as road apples and smells as sweet. I intend to provide a more professional viewpoint.

The content of this blog will not be a regurgitation by an amateur of things learned or plagiarized from books, magazines, YouTube videos, or heaven forfend, troll-infested woodworking forums, but will be based on real-world professional experience.

What relevant professional experience do I have, you ask?  To begin with, I worked as a joiner, cabinetmaker and carpenter for many years. I have worked in the construction industry most of my life as a contractor and direct employee of some of Japan’s largest general contractors. You could say I know the trade.

Much of what I know about woodworking and tools I learned directly from the professionals I worked with and tool makers whose opinions I sought out, most of whom have gone to the big woodpile in the sky. You could say I had good teachers.

I no longer use tools on the jobsite, but I am still involved in the Japanese construction industry. I have lived, studied and worked in Japan off and on for around 24 years since first coming here 43 years ago. You could say I know the neighborhood.

I have a masters degree in architecture and engineering from a prestigious Japanese university and am bilingual in both written and spoken English and Japanese languages, so you could say I know how to research and ask intelligent questions about technical subjects and understand the answers.

But what about the quality of the information? As in all things, you must judge the quality of the content for yourself. But here are a few things you should keep in mind when doing so.

We live in a confusing era of fake internet experts, absolutely corrupt journalistic standards, and blogs and publications authored by lazy opportunistic shills. Is this evaluation too harsh? I don’t think so. But whether opinion or scientific research results, a wise man will consider the writer’s motivations which inevitably skew the focus, quality, and sometimes even the veracity of information he presents.

I think there are three common and not mutually exclusive motivations for people to write blogs. One is a desire to share useful, interesting information. I like to think this is my motivation.

Another motivation is a desire to be popular and make money in the process. For these fellows, success is partly measured by the number of “clicks,” “likes,” and subscribers they get, and of course the acreage of banners and adverts on their webpage. Both their self-worth and income relies on infrastructure controlled by monstrously unethical companies like Google, Facebook, Instagram, Twitter, YouTube and Patreon, and the funding of viewers and sponsors. I pity them.

I have no problem with people touting a product or service or belief. Who knows, the information may be useful, so long as it doesn’t include too many lies or exaggerations and the touter is honest about his relationship with the item or service, as I am with my products. Sadly, too many bloggers, YouTubers, and politicians don’t reveal sponsor contributions in cash or goods but pretend their opinions and reviews are unbiased. Such behavior is indisputably unethical. I think a famous French soldier expressed my thoughts about such dishonest people well when he said: “I don’t want to talk to you no more, you empty-headed animal-food-trough wiper! I fart in your general direction! Your mother was a hamster, and your father smelt of elderberries!”

I will never accept sponsorships, contributions, banners, or freebies. I have no SEO goals. Those who want to read the things I have to share must find this blog without guidance from the Silicon Valley decepticons.

Perhaps the third blogger motivation is a disease called “writer’s dysentery.” This horrific affliction makes the victim feel sick in their guts unless they write and post something, anything, everyday regardless of relevance or quality. Many scribbler-types suffer from this frightful disease and practically gush like a trash pump. Thankfully, I am not infected with this malodorous malady. I spend too many hours every working day writing necessary documents for my company and clients and the construction projects I run, so I feel no compulsion to spend my free time writing for free.

Therefore, I will not subject you, Gentle Reader, to diarrhetic descriptions of my vacation, hobbies, boat, motorcycle, kids, grandkids, pets, my grandkid’s pets, or rambling step-by-step descriptions of landfill-ready woodworking projects imitating those eternally recycled in woodworking periodicals, subjects which make up 80% of the content of most blogs.

Now that it’s clear what I won’t write about, let’s look at what I will.

The craftsmen that make and use the tools that are a major subject of this blog are located far from most English-speaking readers, both culturally and as the crow flies. Communication with these people on technical subjects can be challenging. During my years in Japan I have built relationships with these craftsmen and learned much from them. I will share that knowledge in this blog.

I also plan to post interviews with Japanese craftsmen along with photos of their smithies, workshops, and jobsites as time and opportunity permit. Perhaps we can even do a few Q&A sessions with them. Please let me know what interests you in the comments below.

As a construction-industry professional in Japan, I routinely evaluate and hire Japan’s top general contractors and subcontractors for my Client’s projects. I will share some of those stories too (non-disclosure agreements permitting).

Some of the how-to subjects I intend to discuss will include tool setup, sharpening, maintenance and proper usage, as well as how to make some tools. And of course, woodworking techniques.

Regarding the frequency of posts, I am a busy man and dislike wasting time with pointless drivel. I will post only what I think is worthwhile, measured by my standards and your requests, when I can. And I will make no schedule commitments.

The one thing I do promise is the content of this blog will be worth more than you pay for it. You won’t find a better deal anywhere at twice the price.

If you have relevant questions, please ask. If you have suggestions or corrections, I am willing to learn. But to those who would use the internet’s anonymity to morph into snapping orcs or bellowing trolls, I say Go back to the Shadow!

Wanted: Hair Stylist, Esthetician, Ear Manicurist and Tooth Sharpener. Must like caves.

All others I welcome with bunny hugs.

Stan

Do I Need a Shave?

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Setting Up Japanese Chisels

This post contains information for the Beloved Customers of C&S Tools to reference when setting up their new chisels. While you don’t have to do it before giving your chisels a ride around the block, performing these setup procedure is essential to ensure your chisel’s handles will endure hundreds of thousands of hammer blows and provide trouble-free service for many decades. Please, don’t put it off.

Which Chisels Require Setup?

There are several general categories and many types of Japanese chisels. I will delve into this subject in great detail in future posts, but the two general classifications are Tatakinomi (叩鑿)meaning “striking chisel,” which are designed to be motivated with a steel hammer to cut larger quantities of wood, and Tsukinomi (突き鑿), which translates directly to “thrusting chisel,” the equivalent of “paring chisel” in the Western tradition, and are designed to be pushed by hand for paring operations. The setup measures described herein are not entirely irrelevant, but are normally unnecessary for tsukinomi.

Tatakinomi, including oirenomi (bench chisels), atsunomi (oirenomi on growth hormones), and mukomachinomi (m0rtise chisels) are the focus of this post.

Steel hammers are not gentle, so takinomi always have steel hoops or crowns on the end to reinforce the handle and prevent them from cracking and splitting. This crown, as well as the ferrule installed at the blade end of the handle (kuchigane) can be highly stressed in use and failure can occur with unpleasant results. In this post I will explain how to setup your tatakinomi to ensure they are happy and provide you excellent service for many decades of hard use.

Why Should I Setup My Chisels?

C&S chisels are professional-grade tools each hand-forged by a single blacksmith in the traditional manner from plain, pure, high-carbon Shirogami steel. They are not mass-produced consumer-grade tools and will serve you best if you treat them in a professional manner.

Japanese tatakinomi chisels are designed and manufactured assuming the end user will perform some setup work before using them. Performing setup will probably help your chisels perform a little better and will absolutely ensure the handles last longer. And by avoiding the deformation and damage that typically develops without proper setup, you will preserve your reputation as a professional woodworker in the eyes of other professionals.

The chisel shown in the photographs in this post is a variety of tatakinomi called an Atsunomi, written 厚鑿 in Chinese characters and which translates to “thick chisel.” Not a romantic name, but certainly accurate at least in comparison to the smaller, more common oirenomi. It is intended for heavier work such as timber framing. I chose it for this blog post because it is easier to photograph.

This chisel was forged by a famous Japanese blacksmith named Shimamura Kosaburo (RIP) who used the brand Kiyotada, meaning “pure and faithful.” During his lifetime Mr. Shimamura was lauded by experts in the fields of blacksmithing and metallurgy as the finest chisel blacksmith in Japan.

Kiyotada Brand Atsunomi Chisel

Does Chisel Setup Help?

Unlike western chisels, Japanese tatakinomi chisels are designed to be struck with a steel hammer. These impact forces tend to make the handle mushroom and split, but the crown (hoop) contains and compresses the wood fibers preventing this damage. Even then, however, the force of impact does crush and break fibers at the handle’s end so that after decades of use the handle will gradually become shorter.

For the crown to continue to protect the handle properly, it must be able to travel down the handle in tiny increments without gouging and splitting the handle. Also, your hammer may occasionally strike a bit off-center mushrooming the end of the metal crown over time and preventing it from traveling down the handle. If this deformation becomes too great, the mushroomed crown will dig into the handle damaging and weakening it. The crown must therefore be chamfered to prevent deformation and to allow this travel to occur without gouging and splitting the handle

The truncated metal cone or ferrule that fits between the handle and blade is called the kuchigane (口金), which translates to “mouth hardware.” It serves to keep the hammer impulse forces from splitting the handle, but if it does not fit tightly, or if it digs into the handle, it can weaken it, so the wide end of the kuchigane must be deburred and chamfered. In some cases, the handle may need to be shaved to properly accept the kuchigane. The following pictures show what these measures will help avoid.

Split Handle
Mushroomed Crown and Handle Crack

Tools and Materials

  • Masking tape
  • Fine point marking pen or ball pen
  • Sharp knife for cutting wood
  • Sharp knife or deburring tool for deburring and chamfering mild steel (an inexpensive kiridashi kogatana with an edge sharpened to 45 degrees shaves metal faster and cleaner than a file)
  • Rat-tail file or chainsaw file (can also be used for deburring)
  • Flat mill file
  • Pliers
  • Block of hardwood for driving off crowns
  • Wet/Dry sandpaper (220, 320, 600 grit)
  • Satin varnish or polyurethane and thinner
  • Gas stove or propane torch (optional; outdoors use)
  • Silk cloth (optional)

Disassembly

Step 1: Safety first. You will need all your fingers for this process. Tape some cardboard around the cutting edge so they remain attached to your hands.

Step 2: Remove the crown (hoop). Grip a block of hardwood tight against the handle, with one end butting up against the crown. Strike the opposite end with a hammer. Work the block around the crown and repeat until the crown comes off.

Remove the Crown
Mark Orientation of Handle to Blade

Step 3: Mark the blade’s orientation on handle. Place a mark or arrow on the end of the handle in line with the flat of the blade to help you reassemble the handle in the same orientation. If you are setting-up multiple chisels at the same time, write the blade width on the handle’s end to avoid confusion later.

Step 4: Separate the blade from handle. If the process of removing the crown did not loosen the blade, hold the blade in one hand and strike the kuchigane against the corner of a wooden workbench or block of wood. The best locations to strike the kuchigane are at points in line with the corners of the square tang, as seen in the photos of the bare tange below. Notice how the tang’s flats are aligned with the top and bottom of the blade.

Strike each corner twice, then shift the point of impact 90° and repeat. The goal is to gradually rattle the handle off, so don’t be shy. If the blade and handle still refuse to separate, expand the kuchigane and shrink the wood using a heat gun or by placing the kuchigane nearly (but not quite) touching a hot incandescent light for a few hours. Do not place the chisel in an oven!

Rap the Kuchigane to Separate

Step 5: Disassemble the handle and kuchigane. If you are setting-up multiple chisels at the same time be sure to keep each chisel’s components separate and mark them.

The Chisel’s Component Parts

True the Tang and Shoulder

Step 6: The tang and neck/shoulder should meet at a clean 90° angle (although a slight filet is acceptable), and the shoulder should be clean and flat. If necessary, true it up carefully with a flat file. At the same time, flatten and smooth the shoulder, but be careful to only true the shoulder and not file gouges into it. Also use the file to remove burrs and gross irregularities on the tang as necessary.

The tang before cleanup
The tang after cleanup

As you can see in the photo above, the tang does not need to be perfect, just free of big irregularities and burrs that might cause the fit between handle and tang to lossen after hard pounding,

When you are done, there should not be a pronounced gap between the shoulder and kuchigane when the chisel is assembled.

Prepare the Kuchigane (Ferrule)

Step 7: Check the blade end of the handle with the kuchigane in place. If it is a sloppy fit, adjust the handle using knives, files, and sandpaper as necessary.

Step 8: Flatten each end of the kuchigane with a flat file. Be sure the ends are in planes perpendicular to the kuchigane’s centerline

Kuchigane before chamfering

Step 9: Chamfer the inside of the kuchigane’s wide end (not narrow end) with a knife or round file. Shave or file a a 45° chamfer 1/2 to 2/3 the thickness of the kuchigane’s wall on the inside corner of the kuchigane’s wide end. An inexpensive kiridashi kogatana knife or deburring tool with a blade angle of around 40 degrees will easily shave the mild steel used for crowns and kuchigane and works quicker and cleaner than a file.

A stopped hole drilled into a board works well to secure parts when deburring and chamfering them. Vise grips also work well for securing crowns if you pad the jaws to keep them from gouging the parts, but tend to deform kuchigane

Just be careful not to cut yourself. They may be beautiful and very useful, but many chisels and knives are cold vampiric geniuses (genii?) that fear neither sunshine nor spaghetti sauce and want to cut you, so beware! Hold parts in a way the blades absolutely can’t bite you no matter how hard they try. A severed tendon can be a tragic life-changing injury.

Kuchigane after chamfering

Step 10: If you decide to refinish the kuchigane, remove the existing chemical bluing with sandpaper at this time.

Prepare the Crown (Hoop)

The Crown Before Deburring and Chamfering

Step 11: Chamfer both inside corners (top and bottom edges) 45° with a knife or a rat tail file. This step is very important.

The crown after chamfering. This step is critical.

Step 12: Deburr and clean up the crown’s inside surface. However, be careful to not remove too much metal or the crown may fit too loosely.

Deburred, Chamfered, Filed and Sanded Crown

Step 13: Lightly file and sand the crown’s exterior surfaces to remove major irregularities. There is little point in trying to make these surfaces perfectly smooth since they will get banged up by hammers.

Prepare the Handle

Step 14: Check the Depth of the Tang Hole. If this hole is too shallow, the pointy end of the tang will bottom-out and can cause the handle to split. Measure it with piece of wire or a stick. If it is not deeper than the length of the tang, drill the hole just a tad deeper.

Step 15: Check/Adjust Blade Alignment. With the kuchigane removed, insert the tang into the handle correctly oriented, and sight down the handle. If the handle and blade do not line up properly, you may need to correct the misalignment.

To do so, first try fitting the blade to the handle in a different orientation (90˚). If this does not improve things, make thin slips of wood the width of the tang’s flat and fit one into the hole before inserting the blade. Slips made of cardstock, manila folder, or cotton typewriter paper work well too. If you feel a lot of resistance when inserting the tang, attach the kuchigane to prevent splitting.

Thinner or thicker slips can be inserted if more correction is necessary, but there is a point where too many slips will make it impossible to insert the tang without splitting the handle. In this worse case scenario, shave the hole a bit wider with a chisel or other slender piece of steel sharpened as a scraper to permit adequate shimming. Be careful to remove the absolute minimum amount of wood.

Step 16: Check/Adjust Crown Fit. It is acceptable for the crown to leave a shallow ring depression in the handle, but if the crown digs deeply into the handle, shave or sand the handle to ensure the crown will not gouge it.

The Handle’s Coned End Before Fitting

Step 17: Prep the Shoulder. Most chisels have a shoulder turned into the handle where the kuchigane terminates, making for a smooth, attractive transition between kuchigane and handle. This is most pronounced in chisels made in Western Japan. However, if the kuchigane butts tight up against this shoulder, over time the force of the hammer can drive the kuchigane into this shoulder damaging the handle.

Relieving this shoulder with scallops will provide some room for smooth movement of the kuchigane over time. To do this, first mark a line around the handle where the kuchigane ends. Then remove the kuchigane.

Step 18: Wrap a piece of paper or light cardboard 3/16″ to 1/4” above this line, secure it with tape, and using it as a guide, mark another line around the handle with a fine-point marking pen, ball pen, or knife. Remove the kuchigane and paper.

Step 19: Mark the Handle: Use a pen, pencil or marking pen to mark the cone at diagonals across the tang hole and extend these marks to the line you made in the previous step. This will leave four lines 90° apart. Now make similar marks at the flats of the tang and extend the lines. There should now be eight lines separated by 45°.

Step 20: Cut the Scallops: Wrap masking tape around the cone as shown in the picture below to protect the cone from cuts which might weaken it. With a very sharp knife, make four cuts in small increments centered on one of the lines and forming a concave scallop between the two adjacent lines. Repeat for the other four lines. These curved scallops should transition smoothly into the wooden cone, but should not cut into it. This may not be as easy to accomplish as it seems. If done properly, the scallops should appear very uniform and attractive. Finally, shave off the ridge between the scallops creating a total of sixteen scallops at 22.5°.

Finish the Handle

Some people prefer a handle without any finish, while others like a shiny finish.

Hand sweat tends to react with the tannic acid in Japanese White Oak handles turning them a dirty-looking grey. Japanese Red Oak, as in the handle in the pictures above, does not discolor as much.

Whether you refinish the handle, leave it as-is, or sand it bare is your choice. It makes no difference to the chisel’s performance.

Step 21: Sand the Handle. So at this point, you can either (1) Not sand the handle (unless it is damaged), and varnish the scallops and any areas shaved at the crown end of the handle to match the existing handle finish; (2) Sand off the existing finish entirely to bare wood; or (3) Refinish the entire handle.

Step 22: Apply a Finish: This step is applicable if you decide to apply a finish to the handle. Sweat may cause Japanese White Oak, a wood commonly used for chisel handles, to discolor, so a light finish (not a thick glossy finish) is appropriate in my opinion. The following is the method I recommend. First, sand off any remaining finish on the handle. Apply a coat of satin varnish or polyurethane diluted 100% with thinner. Allow as much of this mixture to soak into the wood’s fibers as possible. Rub the wet varnish mixture forcibly into the wood using wet-or-dry sandpaper. Thinned varnish will penetrate further into the wood than straight varnish, and the pressure of sanding will force it deeper into the fibers than just capillary action. In addition, sanding will create a wood/varnish slurry filling the grain.

Allow this mixture of varnish and wood dust to dry without wiping it off. It will look terrible, but never fear. Repeat these steps for a second coat and allow to dry. Apply a third coat, sand lightly, and then wipe off the varnish slurry with a cloth.

When dry, the result will be a non-slip surface free of lathe marks that does not appear to have any finish, but that will protect the wood from sweat and moisture. If a little bit of visible surface finish is desired, a final single coat of thinned varnish can be applied. To ensure the previously cut scallops remain nice and crisp, do not sand them.

Warning: Do not apply finish to the crown end of the handle because the finish will make the wood fibers too stiff to deform properly. If you want to go the extra mile, a bit of melted paraffin wax or beeswax allowed to soak into the end of the handle will protect it from water and make it more resilient over time than just bare wood.

Finish the Kuchigane and Crown

This is an optional cosmetic step, but will make your chisel more attractive. There are several ways of surface finishing the metal of the kuchigane and crown:

Heat Bluing: Simply heat the kuchigane and crown on a stove until it is blue-black. Not very durable.

Oil Black: Coat the metal with motor oil and heat it until the oil is burnt off. This method makes a lot of stinky smoke, so don’t do it indoors. Fairly durable.

Gun Blue (chemical bluing): Brownells’ cold blue formula works well. Birchwood Casey also makes a convenient chemical bluing product. Looks nice, but not very durable.

Rust Blue or Rust Black: These are classic, beautiful gun metal finishes that are much more durable than chemical or heat bluing. However, the process requires dangerous chemicals and time. A description of the process is not possible here. Extremely durable.

Burnt Silk Finish: This is my favorite finishing method because it is quick and easy and looks good. Simply heat the metal parts over a flame, and using pliers so you don’t burn yourself of course, wipe the metal in a wad of scrap silk. An old silk necktie works fine. The silk protein will char, coating the metal with a carbon finish with an interesting texture. Wipe the metal quickly but thoroughly to prevent globs of melted silk from sticking to the metal. Don’t do this inside the house because the smoke will set off the smoke alarm and the stink will endure for weeks. SWMBO will not be pleased.

Reassemble the Chisel

If this is a new chisel, it may be convenient to sharpen the blade before final assembly.

Step 23: Install the Crown. To begin assembly, hold the handle in the air by one hand and drive on the crown using a mallet, not a steel hammer. You should always remove your wrist watch before wacking chisels, and now is a good time too.

There is a specialty tool for this job, essentially a steel cone that fits over the crown, which you strike with a hammer. If you enjoy spending money on heavy tools that take up space and are seldom-used, then you gotta have one. But a wooden mallet works just as well and can do many more tasks.

Once the crown is flush with the handle, angle the handle and strike the crown with your mallet driving it further onto the handle. It only needs to be driven down so the top of the crown is below the end of the handle by 1/16”. More is wasteful. Then use a steel hammer to lightly mushroom over the corners of the handle securing the crown in place. Do not soak the handle in water.

Soaking the handle in water prior to fitting the crown is a method preferred by handlemakers and wholesalers that fit hundreds of crowns a day. They will soak 50 handles at a time in a shallow pan of water to make the wood softer and easier to deform. The problem with this technique is the water will also cause the wood to swell, and when it later dries and shrinks, the crown may become loose over time. Your handle deserves better.

Step 24: Install the Kuchgigane. Fit the kuchigane to the handle lightly and insert the blade’s tang oriented according to the marks you made previously. Tap the end of the handle to lightly seat the blade, but allow enough room so the kuchigane can be rotated by hand. Rotate the kuchigane to minimize any gaps between it and blade’s shoulder. If you see any big gaps, lightly file the kuchigane to match the blade’s shoulder. If any part of the handle projects past the kuchigane’s mouth, carefully shave it off with a sharp knife.

Step 25: Seat the Blade. Finish seating the blade by holding the chisel in your hand in the air and striking the end squarely with a steel hammer until it seats tightly.

Voila!

Use the Right Hammer

When cutting wood, please use a hammer with a flat face, such as a Japanese gennou, to strike your chisel. A hammer with a domed or convex face, as are almost all hammers sold outside Japan nowadays, will damage the chisel’s handle after enough strikes. Ergonomics aside, a ball peen hammer or claw hammer with its face ground flat will work just as well as a Japanese gennou.

And while we are on the subject of hammer faces, I recommend you smooth and even polish your hammer face so it will strike cleaner and reduce the wear on your chisel handles, counterintuitive as that may seem. Slipping will not be a problem, trust me.

I encourage you select a hammer weight that balances well with the weight and blade width of your chisel, the type of wood and type of cutting you plan to do, and your body and style of work. This decision will make a difference in the precision and speed of your work, the energy you expend, and the stress on your joints.

375gm (13.2 ounces) is a standard medium weight for gennou hammers in Japan, perfect for driving nails, general carpentry work, and motivating atsunomi. However, many find a lighter-weight head, perhaps in the neighborhood of 80~60 monme (300gm/11 oz to 236gm/ 8.3 oz), works better with smaller chisels, such as oirenomi, for furniture and joinery work.

I also encourage you to make a handle for your hammer that suits your body and style of work.

This post is already too long so I won’t go into details, but suffice it to say that commercial hammer handles are a one-size-fits-nobody design that confuses the hand, is un-aerodynamic (I bet you never thought about air-drag in relation to hammer handles), transmits excess vibration to your joints, and ignores obvious ergonomics causing the head to impact the chisel off-center and out-of-kilter. There is a better way, and you will love the results.

But we will dive head-first down that rabbit hole in future posts.

Kosaburo Gennou Head and Black Persimmon Handle

Rust Prevention & Storage

If set up properly, a quality set of Japanese chisels will endure decades of hard daily use with no maintenance beyond oiling and sharpening.

You should store your chisels where they will be protected from weather, water, sudden temperature changes, dust, fly-specs, and paint overspray. Convenient though it may be store chisels in an exposed rack or bare on a shelf, unless you use chisels stored this way nearly everyday and clean and oil them frequently, such storage methods reduce their useful lifespan and will waste your sharpening efforts and sharpening stones sure as eggses is eggses.

I recommend you make a wooden chisel box with a lid to store your chisels. I am preparing an article on how to design and make a chisel box, and will post it on the blog when it is ready.

After every use, oil the blade to prevent rust. An aburatsubo or oilpot is a critical accessory for chisels, and is easily made. You can find details here.

YMHOS

PS: If you have questions, please use the form below. Your information will remain confidential (we’re not evil Google or incompetent facebook).

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