It is well with me only when I have a chisel in my hand
This is the first in a five-part series about the Mortise Chisel, especially the Japanese version.
Also called the “Joiner’s Chisel” in Japan, this is a specialized chisel used by specialist craftsmen to cut precise, smallish joints when making furniture, cabinetry and joinery. Carpenters don’t use it, and few have in that august trade have even seen one.
In this post your humble servant will introduce a tiny bit of the terribly long history of the mortise and tenon joint, and give a description of this specialized chisel.
In future posts we will look at how to evaluate, adjust and even how to use the Mortise Chisel in general and the Japanese Mortise Chisel in particular. We will also touch on bevel angles and blade hardness problems.
We will discuss what to look for in a good mortise chisel and how to examine it with an eye to increasing its performance. This is something most users of chisels never consider, but it can make a big difference in the case of mortise chisels. Indeed, I daresay most Gentle Readers will mutter the equivalent of “Bless us and splash us” when they read it.
Of course we will also discuss how to effectively correct irregularities in our mortise chisel that negatively impact performance, irregularities most people never notice.
After our Mortise Chisel is properly fettled (they almost always have some problems) we will take our racing chisel out for a few laps, but prior to that we will consider how to effectively use this specialized tool. Too few receive proper training nowadays in chisel work, but here are C&S Tools we feel it our duty to help our Beloved Customers improve their skills.
We will conclude this series by taking the “Old Master’s Test,” just to make sure both our Mortise Chisel and our skills are improving.
While focused on the Japanese Mortise Chisel, the principles and improvements discussed in this series of articles are applicable to any chisel used to cut mortises.
While all Gentle Readers with eyes to see, ears to hear, and hands that love wood are welcome to share this hard-earned knowledge, it is intended primarily for our Beloved Customers, especially those who use chisels professionally to keep body and soul in close proximity.
Your humble servant drafted this series of posts years ago, and has shared bits of it with Beloved Customers from time to time when requested, but the information has not always been well-received for a number of reasons.
There is an old Japanese saying, one which probably originated in China, written 「馬の耳に念仏」and pronounced “Uma no mimi ni nenbutsu,” which translates to “Prayers in a horse’s ear.” Why are Buddhist prayers relevant you ask? Good question. You see, some of the principles I will present in this series directly contradict doctrine taught by some of the Holy Woodworking Gurus in the West. Like vespers to a beast of burden, wisdom is wasted on the willfully, woefully ignorant (wow, that almost sounds like iambic pentameter!).
But our Beloved Customers are neither horses nor asses nor politicians but shockingly intelligent human beings to whom your humble servant is convinced the time has come to expound the gospel of the Mortise Chisel as it was taught to me by Masters who have since abandoned this impure world for more ethereal realms.
This series of posts is equivalent to a graduate school course in chisels, something like “Mortise Chisels 701.” And just like a course in advanced differential equations, most Gentle Readers will never need it. But never let it be said that your humble servant didn’t do his best to improve both the skills and the tools of our Beloved Customers.
Some History of the Mortise & Tenon Joint
Mortise chisels are used for cutting rectangular holes in wood usually intended to accept tenons to form a structural connection called the “mortise and tenon joint” between pieces of wood.
No one knows how long humans have been using the mortise and tenon joint, but it has certainly been longer than nails, and many thousands of years longer than screws, although modern humans with their lithium battery-powered, made in China, landfill-bound, multicolored plastic and rubber screwdrivers may find it difficult to imagine. So let’s begin the journey by briefly examining just two well-documented extant physical examples that may provide motivation for using this enduring joint.
The oldest known wooden structure is a neolithic well liner discovered near Leipzig Germany, constructed from oak timbers shaped by stone adze and joined at the corners with half-lap joints and pinned tusk-tenons at through mortises. Tests indicate the trees the timbers were split from were felled between the years 5206 and 5098 BC, making the assembly at least 7200 years old.
Next, let’s look at a less soggy but more recent, complicated and elegant example.
The oldest existing wooden building in the world is a Buddhist Temple named Horyuji located in Nara Japan. Originally constructed around 600 A.D. and rebuilt around 700 A.D. after a fire, this huge 1300 year-old temple and pagoda complex was reconstructed using hundreds of thousands of hand-cut mortise and tenon joints, testifying to the longevity of wooden structural systems and the value of this universal connection technique.
Horyuji is far more than just a temple to Buddhism, it is a temple to woodworking. If you haven’t yet visited it, you’re truly missing something.
I mention these two examples to illustrate the universality, strength, and durability of the mortise and tenon joint. Anyone serious about woodworking must master this most ancient and essential connection.
The mortise chisel is the best handtool for the job of cutting mortises less than 15mm in width. For wider mortises, well-fettled oiirenomi or atsunomi are more efficient.
Japanese Mortise Chisels
In the Japanese language mortise chisels are called “mukomachi nomi” (向待鑿), with “nomi” meaning “chisel.” Don’t ask me the origin of the rest of the word because I don’t have a clue, and have heard few plausible explanations. There is another post linked to here that contains more information about this chisel.
I will use the term mortise chisel in this article to refer to mukomachi nomi.
For our Gentle Readers interested in the Japanese language, there are several combinations of Chinese characters used to write mukomachi, none of which make much sense or seem related in any way to either tools or woodworking. The most common characters used are “向待” with the first character meaning “there” or “direction,” and the second character meaning “wait.” Combined, they seem to mean “Waiting over there,” or something like that.
I assume the name was originally phonetic and somebody decided to use these kanji because their pronunciation matched the phonetic name. This sort of linguistic contortion is seen frequently in Japan, and has been a source of confusion for all and sundry for many centuries. I blame it on elitist Buddhist priests going back and forth between Japan and China over the centuries, but it is typical of the Japanese people in general and priests in particular to take a perverse pleasure in intentionally making and using terms others can’t figure out.
This confusing practice is not unique to bald priests. When I was an engineering student, I recall the professors insisting we never attempt to simplify or too clearly explain the technical jargon of the trade to non-professionals because it was essential to job security for them to never quite understand it.
If you are familiar with Japanese architecture, you have seen the wooden lattice work that defines it in doors, windows, dividers, shoji, fusuma, koshido, glass doors, ceilings, and even fences, all items made by “tategushi” or “joiners” in Japan. Each piece of any lattice needs two tenons and two matching mortises to stay in-place, so a single piece of traditional Japanese joinery may have literally hundreds of small, very precise mortises, indeed thousands in the more complicated pieces. The Japanese mortise chisel was developed specifically at the request of joiners for this type of work. Therefore, it is also known as the “Tategu Nomi” which translates to “joinery chisel.” Few carpenters use this chisel.
Japanese mortise chisels are similar to other Japanese chisels in having a laminated steel structure with a hollow-ground ura (flat), an integral tang, wooden handle, and steel ferrule and hoop. Unlike most other chisels it has a rectangular cross-section with sides usually oriented 90˚square to the hollow-ground ura, and either flat or just slightly hollow-ground to better keep the blade aligned in the cut and to dimension and smooth the mortise’s walls.
Western mortise chisels do not typically share this detail, although unusually intelligent and observant Western woodworkers of course modify their chisels to gain similar benefits.
If speed and precision are important to you, then the sides of the chisel being oriented at 90° to the ura absolutely provide a serious advantage when cutting most mortises because the sides, and especially the two sharpish corners where these three planes meet, will effectively shave and precisely dimension the mortise’s side walls as the mortise is being cut without the need to pare them later.
Unlike most mortise joints cut with oiirenomi or atsunomi, so long as the mortise is the same width as the mortise chisel, and the user has the ability to maintain the chisel at the right angle while striking it with a hammer, the width of mortises cut with this chisel are usually quite precise and seldom if ever need be cleaned with a paring chisel. This functionality means that you can cut mortises, and especially small ones, both precisely and quickly with great confidence. It’s not called the “joiner’s chisel” for nothing.
The mukomachi chisel does not work as well in wider widths because of the increased friction between the chisel’s sides and the mortise’s walls. For joints wider than 15mm, please use a trued oiirenomi or atsunomi. And don’t forget to use your oilpot.
In the next class in our graduate course on the care and feeding of the wild mortise chisel, we will examine the various details to look for in an effective mukomachi nomi. Most of these details are applicable in the case of other chisels such as oiirenomi and atsunomi too, indeed any chisel intended to be used to cut mortises including Western mortise chisels.
But wait a minute! Before ya’ll run out of the classroom like a caravan of crazy stoats chasing a pixie, please pick up your homework assignments from the table by the exit doors. And please, don’t leave your empties behind on the floor. Paper coffee cups are one thing, but diascarded aluminum beer cans attract out-of-work divorce lawyers and other such desperate vermin.
See you next time.
If you have questions or would like to learn more about our tools, please click the see the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.
Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google, fascist facebook, or thuggish Twitter and so won’t sell, share, or profitably “misplace” your information. If I lie may Mama Shishi bite my head off.
Other Articles in “The Care and Feeding of the Wild Mortise Chisel” Series
You can lead a horse to water, but a pencil must be led.
In previous articles in this series about hammers to use with our chisels, your humble servant discussed the varieties of suitable hammers, the appropriate faces on those hammers, and recommended some weight ranges. In this article I will examine some important hammer and chisel techniques Beloved Customer should consider to make your chisel work more efficient and help your chisels last longer.
The Chisel Wiggle
Something to keep in mind about our chisels when beating on them is that their cutting edges are intentionally and carefully hand-forged and heat treated by experienced blacksmiths (none with less than 40 years independent experience) to be especially hard to meet the demands of professional craftsmen for the extra sharpness and cutting longevity only hard, fine-grained steel makes possible. They are not the sharpened Chinese screwdrivers sold by the big corporations that amateurs are accustomed to using nowadays.
To maximize the advantage such excellent steel affords, Beloved Customer must avoid driving the chisel so deeply into the wood when cutting mortises, for example, that the extreme cutting edge binds in the wood forcing the user to wiggle the chisel forward and back to loosen and extract it from the cut. I call this undignified movement the “chisel wiggle.”
Your humble servant realizes this is contrary to what many woodworking gurus teach, but I unabashedly assert that it is careless habit in the case of our professional-grade tools because binding the blade in the wood this way creates what I call a “high pressure cut” placing a tremendous amount of clamping force on the thin metal at the extreme cutting edge. Doing the “chisel wiggle” in this situation will damage the cutting edge dulling it quickly. If you doubt this, please dig out your hand-dandy loupe and do a before-after comparison.
In addition, the time lost extracting the chisel and the resulting interruption in the workflow caused by repositioning one’s hands, and perhaps even setting aside the hammer (egads!) while doing the chisel wiggle, makes it impossible to maintain an efficient cutting rhythm. If you doubt this, we double-dog dare you to do timed comparative tests. The difference in efficiency will become instantly clear.
People accustomed to using Western chisels with their softer, more plastic blades made from high-alloy high-scrap metal content steel with higgledy piggledy crystalline structure are actively taught to use the chisel like a crowbar to lever waste out of cuts. This is another type of “high-pressure cut” that damages the tool’s cutting edge at the microscopic level.
The mass-produced screwdrivers sold as chisels in the West nowadays are relatively soft, can’t be made that sharp to begin with, and they dull significantly during the first few hammer strikes anyway, so most people can’t detect the edge degradation the chisel wiggle and prying create. Those who are satisfied with sharpened screwdrivers don’t buy our chisels so I have no advice for those poor benighted souls, only prayers: Namu Amida Butsu. But it is of little matter: they seldom have the sharpening and tool skills required to tell the difference anyway. Horse, meet water; Ah… not thirsty I see.
The Chisel Cha-Cha
Now that we have explained what not to do, let us examine what we should do instead.
Here is wisdom: A more efficient, more craftsman-like way to remove waste when cutting a joint is to stop striking the chisel with hammer during each cut just before the chisel binds, or just before waste clogs the joint, and then, without changing your grip on its handle, or losing a beat in your cutting rhythm, flick your wrist forwards or backwards so the chisel blade flips the waste out of the joint you are cutting. And Voila! No time lost extracting a stuck blade or setting down and picking up your hammer; and no repositioning your grip on the chisel. And the cutting work can continue uninterrupted without the process of extracting a bound chisel damaging the cutting edge.
Its very much a crisp dance step performed by hammer and chisel with a rhythm something like: “chop, chop, flick, (reposition chisel for next cut)… chop, chop, flick, (reposition chisel for next cut) … chop chop flick.” With each “flick” bits of cleanly cut wood fly out of the joint. But please use your hands for this dance, not your feet.
Next let’s examine the nexus between hammer weight and avoiding the dreaded chisel wiggle.
The Dance of the Hammer and the Chisel
As mentioned above, the way to avoid the chisel wiggle and instead dance the more graceful chisel cha-cha is to avoid banging the chisel into the cut too deeply/tightly. You need to stop hammering just before the blade binds in the cut, precisely controlling the depth to which your hammer drives your chisel, stopping just before the blade binds. Easy to say but difficult to accomplish if the hammer is too heavy. On the other hand, too light a hammer is also inefficient. Therefore, there is no one-size-fits-all-situations hammer weight.
A well-balanced, stable hammer with a handle that fits your hand/arm, and of a controllable weight makes it easier to develop and maintain this precise, unconscious control. Lots of factors are involved but the weight of the hammer/chisel combination is the most important one of the bunch.
How to determine the best weight? It changes with the work and tool and material and the nut holding the hammer so trial and error is the only practical solution. But generally, a hammer that feels a bit on the light side is best. And a good handle makes a world of difference. More on that in future posts, so stay tuned.
The following summarizes the points you should take away from this series of articles so far.
Select a hammer weight that balances well with the width and weight of the chisel, the hardness of the wood you are cutting, your body, and the type of cuts you are making.
The hammer should not be so heavy that you cannot precisely control the chisel’s depth of cut while maintaining an efficient cutting rhythm close to the natural frequency of the hand/arm/hammer assembly;
Don’t drive the chisel so deeply into the wood that it binds forcing you to wiggle the chisel, or heaven forfend, set down your hammer to extract it;
Use your sharp chisel for cutting wood, not for prying out waste like a screwdriver. Instead, use your sharp blade to cut the waste loose and then remove it from the joint by flicking your wrist without stopping, disrupting your cutting rhythm, or setting down your hammer.
There is nothing to stop you from using your hammer and chisel as a graceful but oh so violent dance team, so enjoy!
In the next installment in this tale of bold hammers and graceful chisels we will examine in more detail the rhythmical motions involved in doing chisel-work efficiently and the role of the hammer in that dance. Sorry, no champagne or pretty girls but there just might be a song or two. Until then, I have the honor to remain,
If you have questions or would like to learn more about our tools, please click the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.
Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google, fascist facebook, or thuggish Twitter and so won’t sell, share, or profitably “misplace” your information. May my chisel forever wiggle if I lie.
Other Posts in the Series “Hammers to Use With Our Chisels”
“Do not wait; the time will never be “just right.” Start where you stand, and work with whatever tools you may have at your command, and better tools will be found as you go along.”
The oldest style of oiirenomi currently available nowadays is called the ”kakuuchi oiirenomi” （角打追い入れ鑿）which means ”square-forged oiirenomi,” referring to the squarish shape. In cross section, the blade is rectangular with 4 more-or-less square outside corners. Other than this cross-sectional detail, it is identical in appearance to the mentori oiirenomi we discussed in my earlier post here.
Where the Shinogi Oiirenomi in the previous post is thin and light, the Kakuuchi Oiirenomi is bulkier and heavier. They are also stiffer in the blade and even in the neck, which can be an advantage in narrower widths.
This added stiffness is not due to the extra mass of metal alone, but also to the fact that the steel layer is wrapped further up the blade’s sides than is possible for the thinner beveled sides of the mentori oiirenomi, as you can see in the photos above. Wrapping the high-carbon steel cutting layer up the blade’s softer low-carbon steel sides in this way creates in effect a hardened steel “U” channel with an increased moment of inertia, which makes the blade much stiffer. The thicker the chisel’s sides, and the deeper the U channel, the stiffer the blade will be.
The U-channel construction of Japanese chisels is a clever but subtle structural detail unique in the universe of chisels and one few are aware of.
Carving chisels do not have this U-channel detail and therefore are not as stiff or as tough as chisels that do. When you are considering buying a chisel, this is an important feature to confirm.
This style of chisel is better suited to cutting mortises than mentori oiirenomi (beveled oiirenomi), not simply because they are stronger, but because the squarer side edges tend to keep the blade better aligned in the mortise hole leading to a cleaner cut with a little less effort, especially in contrary wood.
The following are some pictures of two of our Kakuuchi Oirenomi by Nagamitsu, hand-forged, of course, from Hitachi Yasuki Shirogami No.1 Steel (aka “White Steel).
Kakuuchi chisels take less time for a blacksmith to shape than the mentori oiirenomi we discussed in Part 2 of this series. The difference in shaping these two styles of chisels is the added step of grinding the extra bevels that make the mentori oiirenomi sleeker.
Indeed, most styles of Japanese chisels can be obtained with a kakuuchi cross section, including the oiirenomi version shown in my previous post, as well as atsunomi and usunomi, chisels we will examine in future posts.
Kakuuchi-style chisels take a little more effort to sharpen because the area of the bevel is larger, and more significantly, the area of the hard steel layer is greater, but on the other hand, they feel more stable on the stones.
More than a preference for greater weight, stiffness and stability, I suspect most individuals who prefer this old-fashioned chisel are making a fashion statement, something like “brogues not oxfords,” if I can adapt a movie quote.
In my opinion, they are not as elegant in appearance nor as handy as either the mentori oiirenomi or shinogi oiirenomi referenced in previous posts, but they do have undeniable dignity and presence.
What do you think?
If you have questions or would like to learn more about our tools, please click the see the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.
Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google, fascist facebook, or thuggish Twitter and so won’t sell, share, or profitably “misplace” your information. May my dignity perish and my diapers leak.
“The best investment is in the tools of one’s own trade.”
The next variety of oirenomi we will look at is called the ”shinogi oiirenomi” (鎬追入鑿).
Shinogi (鎬) means ”ridge” as in the angled ridge of a rooftop or mountain. It is pronounced “she/noh/gee.” I believe the word was borrowed from the sword world where it refers to an angled ridge design on the back edge of Japanese swords (shinogizukuri 鎬造り). This detail is used not only in tatakinomi but in tsukinomi as well.
Shinogi oiirenomi are beveled like mentori oiirenomi but are different in that the bevels extend all the way to the center line of the blade’s face creating a definite ridge. The thickness of the blade’s right and left edges is typically thinner than oiirenomi making it easier to get into tight corners.
I am very fond of this handy, lightweight style of oiirenomi and keep a 10pc set mounted to the inside of my toolchest’s lid.
The downside to this design is that the chisel blade loses some stiffness compared to other styles, so they are less than ideal for heavy-duty wood hogging.
Some call these ” umeki” or ” dovetail” chisels. Indeed, some blacksmiths will grind the bevels to a very thin edge for this purpose.
My blacksmiths will not create these thin edges for three reasons: First, shinogi oiirenomi are not all that rigid to being with, and thinning the sides further is inviting breakage. Second, warpage is especially difficult to control in thin cross-sections resulting in more rejects and increased costs. And third, people always cut themselves badly using chisels with sides made thin enough to actually fit dovetails. Neither my blacksmiths nor I want that responsibility.
Most umeki chisels do not have the thin sides most people expect.
If you need very thin, sharp sides, you should grind and polish the side bevels yourself. Don’t forget to keep a first-aid kit close by, one you can use with just one hand. Seriously.
Shinogi oiirenomi are available in the same widths as oiirenomi.
In the next post I will introduce an old-fashioned but still useful oiirenomi called the “kakuuchi oiirenomi.” Stay tuned.
If you have questions or would like to learn more about our tools, please click the see the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.
Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google, fascist facebook, or thuggish Twitter and so won’t sell, share, or profitably “misplace” your information. May all my blades dull if I lie!
This article contains information for the Beloved Customers of C&S Tools to reference when setting up their new chisels.
All of C&S Tools’s chisels are professional-grade, hand-forged tools intended for professionals that will use them to make products for their customers. In this article and elsewhere in the C&S Tools Blog we share professional techniques, including chisel setup instructions, with our Beloved Customers so they will know how to improve their tools to provide excellent lifetime service under the hard conditions to which professionals are likely to subject them. These are advanced techniques that even many Japanese professional woodworkers don’t know.
By publishing these instructions C&S Tools is not suggesting our chisels are incomplete or require work by the purchaser before they can be used. To the contrary, our chisels are entirely usable and will provide fine service when new as-is without performing the procedures described below. Indeed the condition in which we supply them is standard for tools sold in Japan, where they were handmade.
Some may find these procedures to be too heavy a burden of time and effort. If, Beloved Customer, you don’t require professional levels of performance and durability, then there is no need to bother with these setup procedures. But please don’t tell anyone that we at C&S Tools agree with the abuse of chisels through amateurish techniques like kigoroshi, or soaking handles in water, or micro-bevels, or using grinders. BS is piled so widely, deeply, and fragrantly on the internet that there is no need to add more.
While your C&S Tools chisels will give satisfactory performance even without executing these setup procedures, they will ensure your chisel’s handles will endure hundreds of thousands of hammer blows and provide trouble-free service for many decades. They may also help your chisels perform more efficiently. And they will protect your warranty. The choice is yours.
Which Chisels Require Setup?
There are several general categories and many types of Japanese chisels. Your humble servant will delve into this subject in greater 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.
Steel hammers are not gentle, so takinomi always have steel hoops or crowns (katsura) on the handle’s end to reinforce and prevent them from cracking and splitting. This crown, as well as the ferrule (kuchigane) installed at the blade end of the handle can be highly stressed in use and failure can occur with unpleasant results, so we highly recommend the setup of these kinds of chisels in accordance with the procedures described below. Indeed, it is a condition of our warranty, as was noted in the invoice you reviewed and approved before purchasing your C&S Tools.
Why Should I Setup My Chisels?
C&S chisels are professional-grade tools, not mass-produced consumer-grade tools. They will serve you best if you treat them in a professional manner, including performing proper setup.
In fact, Japanese tatakinomi chisels are designed and manufactured assuming the end user will perform some setup work before using them. This is traditional. It was not that long ago that craftsmen in Japan purchased chisels as components and made the handles themselves.
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 example chisel we will use in this article and pictured below is a variety of tatakinomi called an Atsunomi.
This chisel was forged by a famous Japanese blacksmith named Shimamura Kosaburo (RIP) who used the brand Kiyotada, written 清忠, meaning “pure and faithful.” A founding member of the Tokyo Chisel Guild, during his lifetime Mr. Shimamura was lauded by experts in the fields of blacksmithing and metallurgy as the finest chisel blacksmith in Japan. I agree with their assessment.
The Purpose of these Procedures
Unlike western chisels, Japanese tatakinomi chisels are designed to be struck with a steel hammer. These impact forces tend to cause the handle to mushroom and even split, but the crown (hoop) contains and compresses the wood fibers preventing this damage. Even then, these impact forces do crush and break fibers at the handle’s end such that over decades of hard use the handle will gradually become shorter.
For the crown to continue to protect the handle properly as it becomes gradually shorter, the crown too must be able to travel down the handle in tiny increments without gouging and/or splitting the handle. A primary goal of these procedures is to ensure this natural progression occurs without the crown damaging the handle.
Occasionally your steel hammer may strike the end of the handle a bit off-center impacting the mild-steel crown. After this occurs a few thousand times the crown may mushroom preventing it from traveling smoothly down the handle without gouging it. Another goal of these procedures, therefore, is to prevent, or at least minimize, this deformation of the crown thereby avoiding damage to both handle and hammer.
The truncated metal cone or ferrule that fits between the handle and blade is called the kuchigane (口金), which translates to “mouth metal.” This bit of hardware is key to the handle design of Japanese chisels because it serves to keep the hammer’s impulse forces from splitting the handle by compressing the handle against the tang under great pressure. This is a genius-level design feature critical to the wooden handle’s durability.
But if the fit between the kuchigane, the blade’s tang, and the wooden handle is a bit off, strange harmonics may develop that may cause the chisel to behave skittishly. Also, if the fit between handle and kuchigane permits the kuchigane to ride-up and dig into the handle after many hammer strikes the handle will be weakened. Therefore two additional goals of these procedures are to ensure the handle, ferrule and tang fit properly to provide efficient transfer of impact forces to the blade, and to ensure the kuchigane will not damage the handle during the hard work to which professionals routinely subject their chisels.
The following pictures show what these measures will help avoid.
Tools and Materials Needed for Performing Setup
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
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)
Step 1: Safety first. You will need all your fingers for this process, and leaking red stuff is sticky, so please tape some cardboard around the cutting edge to ensure your digits remain fully attached to your hands.
Step 2: 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 or other designation on the handle’s end to avoid confusion later.
Step 3: 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 tang 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!
Step 4: Remove the crown (hoop). Now that the blade and handle are separated, grip a block of hardwood tight against the handle in one hand, with one end butting up against the crown, and strike the opposite end of the block with a hammer. Work the block around the crown and repeat until the crown comes off.
Step 5: Disassemble the handle and kuchigane. If you are setting-up multiple chisels at the same time be sure to mark/label each chisel’s components to ensure they can be matched for reassembly. I usually write the blade’s width on the handle’s end with a marking pen and scratch it inside the kuchigane and crown with a pointed scribe.
True the Tang and Shoulder
Step 6: True the Tang and Shoulder: The tang and neck/shoulder should meet at a clean 90° angle, however a slight filet is acceptable. The shoulder should be clean and flat. If necessary, true it up carefully with a flat file, but be careful to only true the shoulder without filing gouges into the tang. Also, use the file to remove burrs and gross irregularities on the tang as necessary. Please remember that the tang will always be hidden, so please don’t weaken it by trying to file it to perfection.
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 loosen 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 Kuchigane: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 the End of the Kuchigane: Flatten each end of the kuchigane with a flat file without removing more material than is absolutely necessary. Be sure the ends are in planes perpendicular to the kuchigane’s centerline
Step 9: Chamfer the Kuchigane: 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 such clamping tools tend to deform kuchigane, so please exercise caution.
Be extremely careful not to cut yourself. They may be beautiful and very useful, but many chisels and knives are cold vampiric geniuses 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 life-changing surprise.
Step 10: Refinish the Kuchigane: If you decide to refinish the kuchigane, remove the existing chemical bluing with sandpaper at this time.
Prepare the Crown(Hoop)
Step 11. Chamfer the Crown: Chamfer both inside corners (top and bottom edges) to a nice round 45° angle with a knife or a rat tail file. This step is very important.
Step 12. Debur the crown:Debur and clean up the crown’s inside surface. However, be careful to not remove too much metal or the crown may fit too loosely.
Step 13: Clean the crown’s exterior surfaces: Lightly file and sand the crown’s exterior surfaces to remove major irregularities. However, 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 the hole in the handle which receives the tang is too shallow, the pointy end of the tang will bottom-out and can cause the handle to split. Measure it’s depth 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.
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 tightly 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. Place a Guide Around the Handle: Wrap a piece of paper or light cardboard 3/16″ to 1/4” above the line of the shoulder, 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 or chisel, 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 uniform and attractive, but perfection is neither attainable nor desirable in a handmade tool. 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 your humble servant’s 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 could achieve. 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. Do not heat the blade! This is an ancient steel-finishing technique, indeed one routinely used to colorize plate armor in medieval times.
Oil Black: Coat the metal with motor or transmission 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. Do not heat the blade!
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 steel finishes that are much more durable than chemical or heat bluing. However, the process requires dangerous chemicals, a fine-bristle stainless-steel brush and time. A description of the process is not possible here.
Burnt Silk Finish: This is one of my favorite finishing methods 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. Do not heat the blade!
Reassemble the Chisel
If this is a new chisel, it may be convenient to true the blade’s ura and sharpen it before final assembly. These tasks are a little easier with the handle removed.
Step 23: Install the Crown: To begin assembly, hold the handle in the air by one hand and drive on the crown using a wooden, plastic or rawhide mallet, not a steel hammer. You should always remove your wrist watch before wacking chisels if you want it to keep working. A word to the wise.
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 must have one. But a hammer 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 wooden mallet or steel hammer driving it further onto the handle. You only need to be drive it down far enough 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, for Pete’s sake!
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 soften the ends making it easier to mushroom. Convenient for them, but bad for the chisel because 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 Kuchigane: 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 by the handle in the air and striking the end squarely with a mallet or hammer until it seats tightly.
Step 26. Final Check and Adjustment of Kuchigane to Shoulder Fit: Now that the chisel is assembled, there is one last check to make. The fit between the blade’s shoulder and the narrow end of the kuchigane need not be perfect (perfection is unattainable for mere mortals) but it does need to be fairly uniform because most of the impulse energy from the hammer flows through this tiny interface. Therefore, if there is a big gap, or if half the kuchigane on one side, for instance, is not contacting the shoulder, the flow of energy will not be smooth and the chisel will feel “skittish.” Examine this fit for gaps and irregularities, and correct them by filing the kuchigane. You will need to loosen the blade and handle enough to insert a small file, but you don’t necessarily need to completely disassemble the chisel.
Congratulations! Your chisel is now setup for professional use.
Use the Right Hammer
When cutting wood with a tatakinomi, 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, may 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 hardware-store 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 60~80 monme ( 236gm (8.3 oz) to 300gm (11 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 non-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.
We will dive head-first down that rabbit hole, screaming like a banshee on fire, in future posts.
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, spilled beer, and paint overspray. Convenient though it may be store chisels in an exposed rack or bare on a shelf, unless your workshop is a temperature and humidity controlled cleanroom, or you use chisels stored this way nearly everyday and clean and oil them frequently, such storage methods are guaranteed to 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.
A Final Note
Since we wrote this tutorial ten years or so ago, we have frequently received questions from Beloved Customers and Gentle Readers about the fact that the chisel setup procedures described therein differ in important ways from those taught by most retailers of Japanese tools in the USA and Europe, as well as those expounded in videos on NoobTube, or posted on the woodworking internet forums.
This Final Note is intended to dispel confusion among Beloved Customers and Gentle Readers on these points.
A question we frequently receive is: “Why does your description of how to setup Japanese chisels vary so much from those in online videos and the woodworking forums?”
A knee-jerk response to this question might be that the questioner should take a big, heaping spoonful of that online advice, then hold their nose and swallow it down, yes, all the way down, …. keep swallowing now, and learn for themselves if it is sugar or BS. As the saying goes: “the proof is in the pudding,” or was it “laughter is the best medicine?” I forget. In any case, while such a hasty reply would be entertaining, it would also be crude and unrefined, and since your humble servant is nothing if not always gentle and elegant, I will instead try to provide a more palatable explanation.
The Long Answer
Yes, Virginia, we have seen the various online videos about setting-up Japanese chisels. The creators of most of them are simply parroting instructions that a long-gone employee of a wholesaler, probably some soft-handed office worker who had never used a chisel professionally, heard from another guy working at a chisel factory assembling hundreds of chisels everyday as quickly as possible from cheap parts, some of which may have been imported from China.
Some of our Gentle Reader are now saying to yourselves: “Wait just one frickin minute there! What do you mean, “made in China!?” Please take a deep breath, smell the napalm, and realize that too many of the components assembled into products in advanced countries are actually made in China at low cost. Poor quality is the natural consequence of procurement policies intended to maximize profits, all other considerations be damned. The components used in C&S Tools’s chisels, however, are all made in Japan of quality materials and to reasonable tolerances.
Here’s the problem: Imagine a chisel handle and/or crown manufactured to such careless tolerances that one must beat the heck out of the handle with a hammer (kigoroshi) to reduce the handle’s diameter enough so the poorly-matched crown or ferrule will fit.
Now ask yourself two questions: (1) How difficult can it be to control the tolerances of wooden handles and mild steel rings? And (2) will permanently crushing the hardwood handle’s cells improve its durability and/or longevity?
Or imagine, if you possibly can (difficult, we know), a handle and its crown or ferrule so poorly matched that one must swell the wood with water to get the crown or ferrule to stay attached long enough to ship the chisel overseas. Is your mind not boggled yet?
Do you think these poor tolerances or either of these ham-handed techniques make for a better chisel, one that will provide good long-term service in the real world? Sadly, this is the grade of chisel with which the PooTube “Creators” and the so-called “experts” on the orc-infested forums have hands-on experience.
The manufacturers of these shoddy tools provide zero warranties. Their products disappear into overseas markets where consumers are accustomed to being deceived as a matter of course, and the quality of most of their competitor’s products in the local markets, essentially sharpened Chinese-made screwdrivers, are of even poorer quality, so there is no backlash, only profits.
If any of this sounds to you like proper quality control or good value for the consumer, then there’s some swamp land located next to an abandoned chrome plating plant in North Korea, shovel-ready for resort development, that’s for sale at an amazingly low price. We read about it on an internet forum, so it must be true. All you have to do is send US$3,000 in small unmarked bills via FedEx to a private P.O. Box in Abuja, Nigeria belonging to Prince Musa Adebayo. It’s a limited time offer, so you’d better hurry ( ͡° ͜ʖ ͡°)
Most of our Beloved Customers are not new to Japanese tools. They have bought the sizzle before, found the flavor revolting, and came to us for real bacon. They want honest handmade tools that meet the rigorous demands of advanced Japanese professional woodworkers. That is what C&S Tools routinely delivers.
The Short Answer
Let’s wrap this up by concisely answering the original question.
First, we promote different chisel setup techniques because the tools our Beloved Customers need to setup are different from those with which the “Creators” on Gooble’s SpewTube and the trolls on the internet forums are accustomed. They are made by true craftsmen, not unskilled factory workers using Chinese components.
Our craftsmen are Japanese gentlemen living and working in Japan using crowns, ferrules, and handles made by them to reasonable tolerances, and the highest-quality hand-forged blades, also made by real Japanese blacksmiths working in their own smithies. Kigoroshi and water soaks are not necessary to setup these chisels, and will in fact harm them.
Second, because our Beloved Customers selected C&S Tools, we assume they are more advanced woodworkers than the easily-deceived amateurs that typically buy hardware store-grade mass-produced chisels, and therefore actually want to do initial setup in accordance with the highest standards, not the lowest. It’s their choice, of course, but it would be unimaginably irresponsible of your humble servant to advocate lesser techniques just to match the posers on GuberLube.
And third, unlike the wholesalers and distributors that peddle hardware store-grade tools overseas at inflated prices, we take our warranty seriously, and therefore actually care about the performance and longevity of the tools we sell. We need our Beloved Customers to set them up properly using the advanced techniques we promote because we have a reputation to protect and a direct financial interest in customer satisfaction.
Five Potential Solutions
We hope this explanation clears up the original question. In addition, the following list describes five solutions to the other problems we touched on above. Sorry, but you’re on your own in the case of Prince Musa:
Purchase only high-quality tools made to reasonable tolerances from quality materials by genuine professional craftsmen and blacksmiths that have long-term relationships and reputations that might be damaged by shoddy quality, not mass-production factories filled with low-wage workers.
Buy chisels and other edged handtools only from retailers (like C&S Tools) that both offer and honor a full international warranty on materials and workmanship, one that doesn’t require you to expend additional funds to benefit from. Good luck finding anyone else;
Beware the posers on Yoogle’s GoobTube (or is it Toogle’s YoobGube? We forget) who enjoy spinning an ounce of BS into 7 minutes of visual entertainment, all without any responsibility for the accuracy, completeness or honesty of their representations;
Beware the howls of the pustulous trolls and the chittering of the execrable orcs scuttling about in the fetid darkness of the internet forums;
And last but not least, always remember the most reliable litmus test for veracity: Money Talks and BS Walks (see point 2 listed above).
Or, you can always try the big spoon test described above (ツ). After all is said and done, bitter lessons stick best.
If you have questions or would like to learn more about our tools, please click the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.
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