The Japanese Gennou & Handle Part 4 – The Varieties of Gennou: Kataguchi, Ryoguchi & Daruma

It’s hubris to think that the way we see things is everything there is.
Lisa Randall

Varieties of Gennou: Ryouguchi Gennou

There are several types of gennou. The most popular is the standard, double-faced symmetrical gennou called the “ryouguchi gennou” 両口玄翁 pronounced ryoh/guchi/ghen-nouh. “Ryou” 両　translates to “both,” and ”kuchi” 口　means mouth, so a ryoguchi gennou is one with a striking face on both ends. This category includes its stumpy brother the daruma gennou, which is a shorter version of the ryouguchi gennou. One face of ryouguchi gennou hammer is flat, and the opposite face is slightly domed. The flat face is used for striking chisels and nails, while the domed face can be used for the last couple of hits on a nailhead to recess it below the wood’s surface. It can also be used for something called kigoroshi (“wood killing” kee/goh/roh/shee 木殺) which we will examine in a future article.

This most popular style of gennou head is symmetrical in all axis, an extremely stable shape making it well-suited for using at many different angles and at different swing velocities to make powerful hits where stability during the swing is important. And stability is often not just important but critical because a hammer that easily wiggles or twists out of alignment during the swing, or jinks upon impact, will make the user look like a child.

Varieties of Gennou: Kataguchi Gennou

Besides the ryoguchi, the other common variety of gennou is called a “kataguchi” (kah/tah/goo/chi 片口 or single-face gennou. “Kata” 片 in Japanese means “one” or “half” and again “kuchi” 口 means “mouth” but for some reason unknown to me this term is used to mean “striking face” in the case of hammers. It has a slightly domed face on one end with the opposing end tapering to a small square face for setting nails. Besides setting nails, the tapered end is handy for “tapping-out” (uradashi) the hollow faces of Japanese plane blades. The domed face of the kataguchi gennou is shallow enough to be used for striking chisels, but is not as good for kigoroshi.

Kataguchi genno include the yamakichi style common to Kyushu Island, the funate or Iwakuni style common to Western Honshu Island and Hokkaido way up north, and several variations thereof.

The hammer pictured immediately below is the “Funate Gennou” 船手 which translates to “boat hand” or perhaps “shipwright” gennou. It is especially suited to driving nails, while it’s tapered tail can be used to make a starting hole for nails, a capability especially suited to ship building.

A funate-style gennou hammer with bubinga handle. The eye has a built-in forward cant. This style is popular in much of Western Japan, but not so much in Eastern Japan and Tokyo.

The face of the tapered end of the funate gennou, much smaller than the Yamakichi-style gennou pictured below. If this end is sharpened it can be used to start a hole for the diagonal nails used to join ship planking, perhaps why it’s name references ship building.

The style of gennou pictured immediately below is called the Yamakichi Gennou 山吉, with Yamakichi meaning “lucky mountain.” This was the working name of the blacksmith on Japan’s Kyushu Island who developed this style of hammer. It’s a stubbier, heavier hybrid of the ryouguchi and funate styles, better suited to chisel work while still being well-suited to driving nails. I am told that Kosaburo received permission from Yamakichi and modified the design slightly to better meet the requirements of his customers in the Tokyo area. If you can only have one hammer with you in the field or when doing installations at the Client’s home or facilities, the Yamakichi gennou is hard to beat. It’s not only useful, but unusual and kinda sexy-looking.

A Yamakichi gennou by Hiroki with an American Osage Orange handle (thanks for the wood Matt!). This is the Kosaburo version of the Yamakichi style which originated on Kyushu Island. The face is not entirely flat, but is still flat enough for striking chisels without damaging them. The tapered end has a square face great for starting and setting nails. it also works well for “tapping-out” plane blades. Not quite as stable as the more symmetrical ryouguchi style, but it’s undeniably more versatile. If you need a gennou for driving nails, including finish nails, as well as striking chisels the yamakichi style gennou is hard to beat.

The tapered, square end of the Yamakichi gennou, perfect for starting and setting nails as well as tapping-out plane blades.

The butt of the osage orange handle. This shape, which we will explain in detail future posts, is a key factor in the handle design on which this series of articles is focused. Osage orange is a very tough, stringy wood used for fence posts, tool handles, musical instruments and bows for millennia. The color is a scary neon yellow when freshly cut, but when exposed to sunlight changes to this interesting color.

The Varieties of Gennou: Daruma Gennou

The daruma gennou (dah/roo/mah 達磨玄翁)　is shorter variation of the double-faced ryouguchi genno, but at the same weight, it’s fatter. It is named after Bohdi Dharma, a Buddhist Monk who was the founder of the Zen (Chan) sect of Buddhism in China, as well as an important person in the history of the Shaolin Temple made famous in Hong Kong Kung Fu movies.

You will remember seeing Shaolin Priests in Hong Kong movies dressed in saffron robes, and with rows of dots decorating their bald pates, jumping around thwarting evil drama-queen warlords with long mustaches.

There are many legends about the Enlightened Dharma, but one story says that, while meditating for nine years in a cave near the Shaolin Temple, his atrophied arms and legs fell off leaving just his trunk and head. Because of this legend, in Japan he is portrayed as an oval-shaped figure without any limbs, and with bushy eyebrows glaring out from inside a red hood. He has come to symbolize wisdom and victory through persistence and endurance. This image has deep roots in Japanese culture.

The daruma genno is named after him because, like its namesake, it’s short, stubby, and round. Religious history aside, at any given weight, the daruma is not as physically stable as the standard genno due to its reduced Moment of Inertia.

The Moment of Inertia refers to the tendency of a body to resist changes in position. Quoting from Wikipedia (which is no doubt taken from some physics textbook): “It is the moment of inertia of the pole carried by a tight-rope walker that resists rotation and helps the walker maintain balance. In the same way the long axis of a dragster resists turning forces which helps to keep it moving in a straight line.”

It is the increased Moment of Inertia that makes a steel I-beam so much stiffer and stronger than a plain steel rod of the same length and weight.

Like the three examples just cited, the standard gennou head has its mass distributed away from the center of its eye, making it more resistant to changes in movement than if the same mass were concentrated in a solid ball.

The math for a rod about a center, which is a close approximation of a hammer head, is I = (1/12) x ML², where I equals the Moment of Inertia, M equals the mass of the rod, and L equals the length of the rod. As you can see from the equation, the Moment of Inertia varies with the square of the object’s length, so that a ball has the lowest possible Moment of Inertia for a given mass, and is the easiest shape to get moving, while a hammer head with its mass moved away from the center will have a much higher Moment of Inertia, and will therefore be more resistant to changes in direction.

For any given mass, the daruma gennou head has less length than the standard gennou head, and therefore has a reduced Moment of Inertia, and so is less stable.

Why is this important? Because you, O Mighty Lord of Thunder, are not a machine, and when you swing your hammer several contradictory forces act on it, sometimes large and troublesome and sometimes small and insignificant, but too often they work to drive the hammer off-course so it misses the target, or more often twists during the swing so that a line drawn through center of the hammer’s face and the center of its mass is not aligned with the target producing a glancing blow that wastes time and energy.

But since a longer hammer head has a higher Moment of Inertia, so long as you do your job it will tend to remain in alignment during the swing, making it more likely to impart more of its energy into the chisel even if the hit ends up being a bit off-center.

It may also be useful to remember that the head of a hammer is moved by the user in a cyclically pattern towards the chisel or nail, striking it, rebounding, and then swung to strike the chisel or nail again and again several times. If the rebound motion is wonky, one must struggle to realign the hammer head for each strike.

Compared to the shorter daruma, the longer standard ryouguchi gennou head, or even Yamakichi gennou, will tend to rebound straight back, instead of twisting, helping the user maintain a steady rhythm thereby saving time. Of course, with practice, the daruma can perform just as well as the standard ryouguchi gennou head, but if you intend to make a lot of fast, hard strokes at various angles, which is common in carpentry and timber framing, a standard ryouguchi gennou with its higher moment of inertia and resulting greater stability is a superior choice.

The daruma gennou has traditionally been the preferred primary hammer for two trades: Joiners (tategushi), who use the daruma to their advantage in a specific way, and sculptors, who don’t require stability but do appreciate a large face. Cabinetmakers, tategushi and tansu makers often have a heavy daruma on hand for assembly work because the high face area/weight ratio is convenient for knocking joints together.

I learned about daruma gennou from a retired joiner in Tokyo who was kind enough to instruct me occasionally over a period of several years in the making of Japanese tategu, especially wooden doors, shoji, and free-standing screens (tsuitate). Nowadays, commercial joiners (tategushi) cut mortises mostly by machine, but traditionally, all joints were cut by hand, so the old boys were required to do very precise work, very quickly, frequently cutting hundreds of small mortises for a single screen or door.

The daruma gennou exceeds at this precise, repetitive, speedy work where the chisel is almost always oriented vertically in the cut, the workpiece is almost always located at an unchanging height from joint to joint, and the hammer is not so much swung at the chisel as dropped on it to ensure a very predictable depth of cut with stability not being a significant problem. In summary, the daruma gennou is especially suited for very precise cuts in narrower wooden components such as door and furniture parts.

For example, when cutting joints in shoji, the material remaining at the bottom of a mortise cut in a stile to receive a rail may be only be 1/4 millimeter thick, almost translucent, so if care is not taken, the chisel will cut all the way through ruining the stile. To avoid this, the joiner must be able to control the depth-of-cut very precisely, and rather than swinging the hammer, it is more-or-less allowed to drop imparting controlled, uniform impact forces than would be more difficult to achieve by swinging the hammer.

For this type of work the hammer should not rebound from the chisel but transfer all its energy to the workpiece for smooth, consistent cuts. When used properly, a daruma genno feels like it’s sucked towards the chisel, and when it strikes, it feels like it sticks to the chisel for a fraction of second with little or no rebound providing more precise control of the depth of cut. This technique takes lots of practice to master.

I have seen carpenters in Japan laugh at a fellow that brought a daruma gennou to a jobsite because the stumpy things are thought by many carpenters to appear clumsy. I must agree. Also, they assume that a fellow that uses a hammer with a face as big as a daruma does so because he has a hard time finding the end of his chisel with a standard hammer. They may have a point.

For reasons unclear to me, Americans and Europeans have an illogical affinity for the daruma gennou. That said, when I need to cut a lot of small, precise mortises, I use one. When I need to cut bigger or deeper mortises, or mortises at angles, however, I bring out a standard gennou of the appropriate weight for the relatively greater stability they provide. If you only have one gennou, the standard ryouguchi style head or even yamakichi style would be a good choice.

In the next chapter in this bodice-ripping yarn of romance and intrigue we will examine a more sinister application of the gennou hammer, namely kigoroshi, or “wood-killing.” Please visit the facilities before reading it to avoid embarrassing accidents.

YMHOS

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The Japanese Gennou & Handle Part 3 – What is a Gennou?

What we have is given by God; To teach it to others is to return it to him.
Gian Lorenzo Bernini

There are as many varieties of hammers in Japan as there are in Western countries. With one notable exception, and in one specific application, Japanese hammers are not especially superior to their Western counterparts. That exception is the gennou (pronounced gen/noh), a hammer intended specifically for striking chisels, adjusting plane blades, and strategically crushing wood included in joints (i.e. “kigoroshi” or “wood killing”). This article will provide a further introduction to the gennou hammer.

What Is a Gennou?

A box-stock, hardware store-grade Japanese gennou hammer with a one-size-fits-somebody handle

The Japanese have different terms for different hammers, of course. A hammer used strictly for driving nails, or banging sheet metal, or driving stakes is called a “kanazuchi” meaning “steel mallet.” A common slang term for this tool is “tonkachi.” The gennou, on the other hand, can of course be used to drive nails, but it’s especially suited to striking chisels and adjusting planes.

I’m told the word “gennou” was borrowed from the name of a Buddhist priest who lived, or so the story goes, in the 1300’s and used a steel hammer to destroy a poisonous rock that was troubling the common folk. I’m not sure what one has to do with the other, but there you are.

The Attraction of the Gennou

Many Japanese craftsmen develop an emotional attachment to their gennou, perhaps because, unlike saws, chisels, and planes that are gradually but inevitably sharpened away till little remains, or squares or marking gauges that loose tolerance, get bent or wear out, a quality gennou will last for a lifetime relatively unchanged other than the occasional replacement handle. A good gennou is a simple, reliable, hardworking friend that never complains. It doesn’t have a tail limiting it’s movement and greedily swilling electricity, or batteries that die at Murphy’s whim; It never needs to be sharpened. And most importantly, it will never ask to borrow your truck, or pose a dangerous question like “do these pants make my butt look huge?”

Why Use a Gennou for Chiselwork?

This is a questions we addressed in a previous post, but which we also examine further here.

Almost any striking tool, from steel hammer to leather mallet, can be used to strike a chisel. The problem is that, unless one is either gentle or the handle of the chisel is reinforced, a steel or even brass hammer will eventually destroy the chisel’s handle. The solution in the West has been to use a mallet made of wood, leather, rubber, or plastic instead to cushion the blow and preserve the handle. Let’s consider this for a moment.

The purpose of striking a chisel with a hammer is to transfer the energy of the user’s arm and hand into the chisel via the movement of the hammer head driving it into and through the wood cutting it, right? But a soft-faced hammer/mallet, be it made of wood, plastic, rawhide or rubber deforms when it impacts the chisel cushioning the blow and wasting energy through deformation and heat generation. It may also unnecessarily waste energy through air drag, as we discussed in the Part 2 of this series. Since energy is lost, more mallet strikes are necessary, wasting time. This is demonstrably counter-productive.

Besides being relatively soft, a fat-faced mallet is bulkier, slower to swing, and is therefore less precise than a slimmer steel hammer of the same weight. While there may be some that are thrilled with cutting slowly and expending extra time and energy in the process of cutting a joint, most people want to cut as much wood as possible, as precisely as possible, in the shortest amount of time as possible, and with the least energy expenditure possible.

But if a chisel handle is so fragile that one must expend extra time and energy to keep it intact, then it is only logical to conclude that there is something wrong with the design of the chisel.

The Japanese are very serious about woodworking, as anyone who has gone to Kyoto or Nara and seen the ancient wooden temples there can attest. When it comes to chisel work, Japanese carpenters don’t tolerate such silly nonsense as a chisel that must be coddled, and so early-on Japanese craftsmen developed a wooden-handled chisel that can be struck hard with a steel hammer all day long without breaking.

The excellent design of the Japanese chisel combined with the quality of steel, and the forging, lamination, and heat treatment techniques used in manufacturing most Japanese chisels provides a tough cutting edge that stays sharper longer, placing Japanese chisels at the very top of the evolutionary pyramid of chisels, IMHO. And as the Japanese are wont to do, they developed a hammer specifically for striking chisels.

Technical Matters

The gennou is a simple tool consisting of a steel body of one shape or another attached to a wooden handle. The head has a rectangular hole or mortise called the “eye” in English and “hitsu” in Japanese that receives the wooden handle’s tenon.

The steel used for modern gennou is typically a standard, high-carbon Japanese tool steel used for making hammers, axes, farming implements and many other tools and designated “SK.” Chemically, it is very similar to 01 steel in the Americas; Not as pure as Hitachi Metal’s Shirogami or Aogami steels, of course, but still completely adequate for hammers. I wouldn’t pay extra for a gennou head made from Shirogami steel, much less rainbow-anodized unobtanium, and you shouldn’t either.

Mass-produced gennou are either cast or drop-forged very inexpensively. The eyes are rough and the handles are secured with wedges. Indeed, the eyes are typically so irregular that the head will not stay on the handle without wedges, but a high-quality gennou with a good eye and a handle made by a skilled craftsman doesn’t need wedges or other silly contrivances that compensate for sloppy tolerances to connect the two. “High-quality” is the key word.

Irregularities

A low-quality gennou head with a rough and/or irregular eye can create unnecessary problems for the user so it is important to understand and properly evaluate this negative space.

“Irregular” has several connotations in this context, but one common irregularity is an eye that is skewampus (please forgive your humble servant’s use of a few technical terms). For instance, it may have curved, twisted walls, wonky interior dimensions, or interior corners that are not clean and square. Not only is it a right pain in the tuckus to make a handle to fit such an eye, but you can bet your sweet bippy it will produce strange vibrations and cause the handle tenon to loosen up sooner.

Another irregularity commonly seen in the eyes of poor-quality gennou is rough interior walls. You would think that rough walls would generate higher friction and grip the tenon better, and perhaps they do compared to highly-polished walls, but rough, uneven walls tend to wear-out the wooden tenon of the handle quicker causing it to loosen over time. Imagine the vibrations the tenon is forced to absorb through those walls and the grinding action between wall surface and handle that results.

An intentional irregularity frequently seen in consumer-grade hammers is end walls (versus the longer side walls) that are sloped from each opening towards the center of the eye, essentially making the eye bulge inwards at its center. The purpose of these bulges is to crush the wood of the tenon when it is forced into the eye, increasing friction, while also providing a dovetail-like area for the steel wedge to expand the eye back into. It’s a reasonable solution for rough, irregular eyes in low-cost hammers to be used by amateurs, but one that the craftsmen who truly understands gennou and wants a lifetime tool finds undesirable. We will touch on this detail more in future posts.

Still another irregularity the careful craftsman must watch out for is an eye that is not perfectly centered in both axis in the head.

You might think that an eye that is a little off-center wouldn’t make a big difference, but it does because, not only is the balance and center of mass of such a head also skewampus so that the head tends to twist during the swing and then wiggle on impact, but because making handles for such a head is unnecessarily troublesome. A clean, uniform, straight, properly-centered eye is worth every penny it costs, especially if you are a professional and consider your time and sanity of any value.

Correcting Irregularities

A difficult question your humble servant is frequently asked is “how much irregularity is acceptable?” The answer is simple: If you think it is too irregular, then it is, because the work to correct the defect or compensate for it will all be on you. Sadly, most, including YMHOS, learn the answer to this question only through aggravating experience

Please understand that correcting major defects in hammer eyes is hard work. It takes time, concentration, a good eye, a flashlight, and a deft hand with skinny files and rulers to remove just the right amount of metal in just the right places inside that narrow eye, a task that is much more difficult than removing metal on an exposed surface because the files are thin and bendy, it’s hard to see what you’re doing, you don’t have much leverage, and consistently making a straight pass is not easy. Blisters will bloom. Patience will be tried. Sanity may quiver. Try it yourself and you will quickly see why.

This is the whole point of high-quality heads like those made by Kosaburo and now Hiroki and why they are worth the high cost: Their eyes are true when new, no adjustment necessary, saving the purchaser many hours of tedious work and blisters over a lifetime of hard use. Every time you make a handle for a high-quality head it saves time and leaves you with a good feeling. It’s a true friend, one whose dog never craps on your lawn.

On the other hand, a poorly-made head is a curse, a money-pit (if your time is worth anything), and a frequent source of irritation, especially when it inexplicably abandons its handle and soars as free as a hardened-steel bird (ツ)。

The Pig’s Ear

I hate to say it, but Beloved Customers and Gentle Readers should beware of one last defect when purchasing an expensive handmade gennou head. A perfect eye is truly a difficult thing to make, certainly more difficult than making a head cosmetically beautiful. Unfortunately, one or two famous blacksmiths (who shall remain unnamed in this series of articles, so don’t ask) have earned a reputation among knowledgeable professional woodworkers in Japan for occasionally making aesthetically beautiful gennou with skewampus, eyes. Caveat emptor, baby. She may wear high-heels, a short skirt and be beautifully made-up, but if she has a curly tail and oinks she’s probably a pig in a wig, unless she’s a trans-boor.

If you cannot hold and inspect an expensive gennou head in-person before concluding the transaction, at least make sure you purchase from someone with a solid guarantee, one without weasel-words and that reimburses you for return shipping, like C&S Tools’ guarantee does. A guarantee that you must argue about and then spend more money to benefit from is less than half a guarantee IMO.

We will delve further into the tempering and differential hardening of gennou, as well as laminated gennou heads in future posts in this series, same bat time same bat channel.

The Flawed Face

When it comes to wacking chisels, the garden variety hammer sold in both Japan and Western countries has a distinct design flaw. Namely, a domed face which works well for driving finish nails below the surface of lumber and gypboard, but with much use tends to damage the wooden handles of Japanese chisels by dishing in the handle’s end causing the katsura hoop to loosen, eventually deforming the hoop to the point the hoop in turn gouges and damages the handle. This can even result in the handle cracking or splitting. Yikes!

Using a flat-faced hammer easily solves this failing. The Japanese “ryouguchi” double-faced gennou has one face that is forged flat, for striking chisels, and an opposing domed face for driving nails or performing “kigoroshi.”

And while one absolutely can grind the face of a Western claw hammer flat and use it to strike Japanese chisels without any problems, the gennou is designed specifically for striking chisels. In your humble servant’s opinion, it is a superior tool for the intended purpose.

In the next post in this series we will examine three varieties of gennou to help you decide which is best for you.

YMHOS

The 5-layer Pagoda at Horyuji Temple, registered as one of Japan’s National Treasures. Yessireebob, a lot of hammer and chisel work went into making this structure.

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The Japanese Gennou & Handle Part 2 – Ergonomics

A Kosaburo hand-forged gennou head hung with a Black Persimmon handle. This was the first professional-grade hand-forged gennou head I purchased many moons ago.

“We become what we behold. We shape our tools, and thereafter our tools shape us.” –
Professor Marshall McLuhan

Marketing and mass-production have changed many things, but not how the human body works.

In this post we will examine some ergonomic factors of hammers Gentle Reader may find interesting, and ask some questions you may want to consider.

Ergonomic Factors

Making tools that fit the user’s body and way of working is an old idea. Here is an example.

Since the days when your humble servant was a scrawny kid with a Daisy BB gun, I have enjoyed making rifle stocks. As I matured, my efforts turned to marbled walnut stocks for bolt-action guns and curly maple for flintlock longrifles. But a custom gunstock is not just a chunk of beautiful wood, ooh no.

During my research into the art I learned how craftsmen have, for centuries, made custom shotgun and rifle stocks to fit each customer’s body. Indeed, unlike factory stocks, custom gunstocks are not straight, but are bent, twisted and offset in subtle ways to fit their user’s bodies and to provide a steadier hold, quicker target acquisition, and reduced recoil.

For similar reasons, professional golfers have their custom-fitted clubs, pro baseball players have their handmade custom mitts, pro basketball players have their custom sneakers, and F1 race drivers have their custom-made brain buckets.

These techniques work.

Indeed, like a bespoke suit or custom boots, there are a number of measurements that must be made of the user’s body and the rifle’s components. Yes, and numbers must be crunched in advance of designing a custom rifle stock. I’m talking about a rifle made using thousands of dollars of wood and precision-machined steel, designed to fit a particular person’s body, and intended for a particular type of shooting, not a K-Mart blue-light-special killer of unsuspecting tin cans.

Through study, testing, trial and error and handwork I learned how employing these ergonomic principles could yield significant improvements in the performance of everything from reproduction flintlock longrifles to 1,000 yard target benchrest guns, and even .45 caliber bolt-action elephant rifles. When I heard that a group of specialist Japanese carpenters had, over centuries of experimentation, developed tool handle designs that applied similar principles, the pieces clicked together in my mind like a Purdy double-gun’s breech.

A hammer is not a complicated piece of precision machinery like a modern benchrest target rifle, so we tend to think of them as dumb, crude tools lacking all finesse, but I disagree for they can talk to those who have ears to hear. Let us consider some of the challenges the lowly hammer faces and which they will communicate to us if we but listen carefully.

The first challenge is air drag. The hammer is the most dynamic handtool a woodworker uses, moving relatively long distances at relatively high speeds. And during the swing the hammer pushes a lot of air aside creating drag and expending energy along the way. It adds up.

This is just one reason why big-faced mallets are inefficient compared to the steel hammer. There are those who, reveling in their ignorance, dispute this fact, but to them I say: There is no medicinal cure for stupidity so I encourage them to learn some basic math. If you remember your freshman physics classes, you will recall that the formula for drag in a fluid (which includes air) is as follows:

$F_{D}\,=\,{\tfrac {1}{2}}\,\rho \,v^{2}\,C_{D}\,A$

where F _Dis the drag force produced by an object’s movement in a fluid, ρ is the density of the fluid, v is the speed of the object relative to the fluid, A is the cross sectional area, and C _Dis the drag coefficient, a dimensionless number.

The drag coefficient depends on the shape of the object and on the Reynolds number $Re={\frac {vD}{\nu }}$ ,

You don’t need to input actual numbers into this formula to see that the two factors we, as craftsmen and nail benders, can readily control are the area of the hammer (A) and its speed (v). The factor that we can manipulate to our benefit when designing our handle is the area (A), which includes not only the size of our hammer’s face but the width and length of its handle.

The second challenge the hammer must deal with is alignment during the swing because when using it we draw its head back beyond the range of our vision, and then, without looking back, swing it with great force to precisely hit targets as small as a nail head, while hopefully avoiding hitting our own head, ear and hand. If the hammer’s head naughtily wiggles out of proper alignment during the swing, a bruised ego, bent nail, headache or smashed finger may result, so we need a hammer head and handle combination that will be easy to instinctively keep in alignment during the swing without a thought.

The third challenge our hammer must overcome is the tendency of its striking face to impact the target with its center of mass misaligned with the centerline of the nail or chisel, or with the striking face canted forward, backward or to the side instead of square to the target’s centerline. Think about this next time you bend a nail or your chisel cuts in one direction when you intended it to cut in the opposite.

A person proficient in using mass-produced hammers has no choice but to make their eye and body match the hammer they are using at the moment. Of course, this can be done, but it is inefficient, uncertain, and frankly, bass-ackwards. What I am proposing in this article is that we design our hammer handles so they match our individual bodies and the work we need it to perform instead of forcing ourselves to adjust our grip and swing to fit standard one-size-fits-nobody hammers.

A lot of well-spoken, well-dressed and intelligent-looking blowhards (aka “marketing pukes”) give lip-service to so-called ergonomics, but here at C&S Tools ergonomics really matter for we strive to always hit the nail or chisel squarely instead of just meeting quarterly sales goals of tool-like products. Indeed, in future posts in this series we will discuss in great detail a number of ergonomic factors our Beloved Customers should include in their gennou design specific to their individual bodies and style of work, including the length of the hammer handle, twist and offset, grip location and shape, etc. handle details to help the gennou index automatically in the hand without having to actually look it, and of course, the angle of the head.

We will both explain why and show you how to design, draft, and make a hammer handle suited to overcome these challenges while in your hand.

Three Questions

I am not fond of gaudy, decorated tools, but that does not mean my tools are plain as mud.

As you may be able to tell from the photographs of one of my favorite gennou in this article, I enjoy subtle details that give them a unique, attractive appearance, especially if those details improve their performance while pleasing both my eyes and hands. I don’t know if they have shaped me, as Professor McLuhan suggests, but they certainly give me more confidence and joy in my work than a run-of-the-mill rubber-handled blister-maker ever could.

For years I have encouraged people to ask themselves three questions on the subject of hammers. So I pose them to Beloved Customers and Gentle Readers now.

First, does your hammer and its handle fit your body and style of work, or is it a “one-size-fits-nobody” product made by a conglomerate that knows everything about selling hammers but nothing about using them?

Second, is your hammer aesthetically pleasing to your eye and an extension of your hand, or is it like every other hammer that ever fell off the hardware store’s rack?

And finally, is your hammer likely to be a trusty partner in your woodworking projects, maybe even becoming an heirloom appreciated by your descendants, or will it be discarded to spend its days rusting away sad and lonely in a landfill?

If you answered nay to any of these questions, I promise you will find something of value in this series of articles.

In the next document in this series on designing and making gennou handles, we will examine some history and the ergonomic factors that resulted in the design that is the subject of this series. Until then, I have the honor to remain

YMHOS

Please share your insights and comments with everyone by using the form located further below labeled “Leave a Reply.” We aren’t evil Google, facist facebook, raunchy Reddit, or a US Congressman’s Chinese f*k buddy and so won’t sell, share, or profitably “misplace” your information. May dogs and puppies forever hate me if I lie.

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Previous Posts in The Japanese Gennou & Handle Series

The Japanese Gennou & Handle Part 1 – Introduction

I do think a carpenter needs a good hammer to bang in the nail.
Oliver Reed

Introduction

This is the first in a series of articles about the Japanese gennou hammer in general (written 玄翁 in Chinese characters and pronounced “gen/noh”) and in particular how to design and make a unique one that perfectly fits your body and style of work.

The objective of these articles is to share with you, Gentle Reader, what your humble servant has learned over the years about gennou handles to help you design and make your own.

I will gladly share the entire series, including the drawings, as a single document with Beloved Customers upon request.

The True Craftsman Makes His Own Tools

A handful of generations ago quality high-carbon steel was difficult to make and expensive, so woodworkers worldwide, especially Japan, could not afford many tools, and the ones they did own or inherit were very important to them.

At least partly to reduce costs, it was standard practice back then for a woodworker (or his master) to commission the metal parts of his tools, such as the heads of his axe, hatchet, adze and hammer, and the blades of his chisels and planes from the local blacksmith. In the United States or other British colonies a craftsman may have purchased chisel and plane blades imported from Sheffield, but he would not want to pay the high costs of shipping wooden components across oceans and over mountains when he could make them himself. After all, woodworking was his business, so a self-respecting craftsman would make all the wooden components of his tools himself as a matter of course. Needless to say, those old boys knew how to make handles.

But things have changed. You may not realize it, but we live in a time of extreme wealth where even the poor live better than kings did 200 years ago, partly due to widespread industrialization making the necessities of life, and even what would have been called luxuries, available to everyone cheaply. This industrialization combined with cheap transportation has resulted in the prevalence of craftsmen purchasing pre-manufactured things, including tool handles.

Accustomed to the easy availability of standard mass-produced tools, lacking a clue about performance and focused like a laser on lowest cost, most woodworkers nowadays get by with colorful but poor quality tools designed by kids using computers working in marketing departments that have never used a handtool professionally, and fabricated by farmers in Chinese factories from higgily-piggily scrap metal. These tools may look great on the internet or wrapped in theft-proof plastic containers hanging on pegs in the big-box retailers, but how do they perform? And how long will they last? And what do they say about the men using them? Tools are terrible gossips, you know.

Gentle Reader cannot purchase a hammer handle like the one we will discuss in this series, and no one can make it for you. A hand-forged gennou head fitted with a handle made in accordance with the guidelines presented in this series will become a unique lifetime tool and the sure sign of a superior craftsman. More importantly, it will help you work more efficiently and precisely, make the joints in your shoulders, arms and hands hurt less, and give you greater confidence in your skills.

If you think this all sounds too good to be true, I challenge you to put it to the test. In fact, there is a series of performance tests listed in the last post of this series (when it is published, see link at the end of this post) that will allow you to generate hard proof of the truth of these claims for yourself. You will be impressed with the results.

While Japanese hammers are the primary focus of this series, you can apply the ergonomic principles and solutions I will describe to all varieties of hammer handles.

Modern Tools: Marketing, Design & Manufacturing

I grew up using hammers designed for maximum sales in a competitive marketplace of amateurs, of the type I call “One Size Fits Nobody.” Back then they were made in the USA, but nowadays they are cheaply mass-produced in China. Prices are rock-bottom, and quality is focused solely on getting an attractive product to the big-box retailers at the right price-point while fending off the slavering hordes of snaggle-tooth lawyers that specialize in product liability and personal injury lawsuits. To these corporations, you and I are beasts in a herd, of no import beyond the contents of our wallets and our willingness to empty them.

Like the cover of a manga comic book, mass-produced modern tools are carefully designed to immediately draw the eye and excite the senses of those passing by. Bright colors and futuristic shapes war with each other for attention on the pegboards of big-box retailers. Handles are made of plastic and rubber fitted over cast steel or molded fiberglass, secured with globs of glue intended to hide malformed ulcerous eyes.

The designers of these blister-makers and nail-benders intend their products to age poorly so they will be discarded by purchasers after just a few years to ensure unending sales of “new-and-improved” replacements. Plastic and rubber are the materials of choice because they are cheap to fabricate, easy to make into colorful, exciting shapes, and speedily surf the spiral wave into the depths of the toilet of planned obsolescence.

The international playboy that Billy Crystal introduced the world to in “Nando’s Hideaway” might have been talking to one of these hammers when he said “This is from my heart which is deep inside my body: You look mahvelous, absolutely mahvelous dahling. Remember, it is better to look good than to feel good.”

Perhaps these tools do look mahvelous hanging on those pegboards. But how good do they feel?

The tool conglomerate’s product development departments and marketing geniuses have taken the Latin Lover’s philosophy to heart. They know that tools that look good and turn to garbage quickly are more profitable than efficient tools that merely feel good. I am sure ‘Nando would go “crazy nuts” if he observed modern hammers in their natural environment, but alas my friends (saludos, my darlings, you know who you are), Nando will not make the journey to a big-box home center to inspect their pegboard tools because he does not feel good.

Clever people, these marketing strategists, stuffing their pockets with money and landfills with plastic and scrap metal by selling imitation tools to the herd. But as for me, I’ll have none of that churlish fraud, thank you very much.

Would you buy a hammer like this? If so, please don’t call yourself a craftsman or operate heavy equipment.

Wow, a comprehensive torture kit. And just the right color too. Please don’t puke on your computer or smartphone.

Hammer Handle Morphology

The hammer is an extremely simple tool, literally as old as humanity. I suspect humans made the first multi-component tools by attaching wooden handles to stones to make hammers, axes and clubs.

But despite millennia of history, modern folks have all but forgotten how to make a proper tool handle. It wasn’t always that way. Everyone made their own replacement handles only five generations ago, and their expectations were guided by sweat and blisters. They didn’t need product development departments in Shanghai to tell them what handle worked best.

Axes are an obvious example of how marketing has morphed handle design. Take a gander at an old tool catalog and notice how axe handles have become thicker in the last 120 years. Do these changes mean that for millennia humans didn’t know how to use axes or make proper handles for them? Do modern human joints and tendons endure the higher vibration and impact forces a thicker, heavier, stiffer handle transmits better than those of our forefathers? Has the nature of modern trees changed such that grain runout no longer weakens a needlessly recurved handle made from their wood?

No, these recent changes in handle design are not intended to make tools more functional or more durable, but are rather to increase sales of cheaply mass-produced tools of apparently innovative design, mediocre quality and disposable utility. They simply look mahvelous, absolutely mahvelous dahling, especially as a picture on a website or hanging on a peg in a hardware store.

Please, don’t get me started on modern mass-market saw handles.

In the next article in this series about beaters we will look at the ergonomics of hammers. Until then, I am profoundly honored to remain,

YMHOS

PS: Here is an excellent article about the “Devolution of Axe Handles” that jives well with my research and experience, and the advice my grandfather gave me about making an axe handle 50+ years ago. And just to prove that we at C&S Tools have refined tastes, here’s some music from Fernando.

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Subsequent Posts in The Japanese Gennou & Handle Series

Hammers to Use With Chisels Part 6 – Hammers & Health

A box-stock hardware store gennou hammer. Delicious Ambiguity. A good place to start.

I wanted a perfect ending. Now I’ve learned, the hard way, that some poems don’t rhyme, and some stories don’t have a clear beginning, middle, and end. Life is about not knowing, having to change, taking the moment and making the best of it, without knowing what’s going to happen next. Delicious Ambiguity.
Gilda Radner

In previous posts in this series about hammers to use with C&S Tools’s chisels, we looked at factors such as the type of hammer to use, the sort of face a hammer should have, how much it should weigh, and how to use hammer and chisel as a graceful dance team. In this final post we will look at how hammers can impact our health.

Health Matters

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Swinging a hammer is a violent movement that places large, repetitive impact and vibration stresses on joints, tendons, nerves and muscles. These stresses can make our bodies stronger, or break them down. Carpel tunnel syndrome in office workers clicking away at computer keyboards gets all the attention, but hammers are much more likely to cause health problems. Before nailguns it was common for carpenters to have nerve damage in their hands and arms, but chopping dovetails with a pneumatic chisel is not an option.

When your humble servant was a young apprentice carpenter working in Las Vegas I wanted to be like the older more experienced carpenters on the jobsite that used shiny 32oz waffle-face Vaughn hammers to drive 16d nails through stacked 2×4’s in a single swing (this was before the advent of nailguns and LGS studs). I got where I could do that. I still own that hammer, but like me it is no longer smooth and shiny. I have replaced the wooden handle 3 or 4 times. Would that I could do the same with my knees.

I barely remember him, but he was a young man with lots of energy focused on gaining respect and being productive. Fortunately, I was blessed to work on crews led by older guys with no ego left, whose joints ached (like mine do now), and who just wanted to get as much good work done as efficiently as possible each day until beer-thirty. What I learned from them went beyond wacking nails, and more about actually building things.

At first I wondered why the bosses would hire old farts when younger guys moved faster and got more work accomplished. What I learned, however, was that, while the old guys did not appear to be as active as the younger carpenters, by the end of the day they had always accomplished more actual work, and with less rework. It was difficult for the young man I was back then to accept, but the bosses new their business, including two important points:

“Fast” and “productive” are not the same thing (the tortoise and the hare principle, “Festina lente“);
Rework takes more than twice the time and money to accomplish than doing the work right the first time.

These two principles are key to being a successful professional woodworker, so a forehead tattoo might help Gentle Reader to remember them. Just a suggestion….

None of those old boys I worked with used extra-long extra-heavy hammers because they knew that productive work required driving nails of different sizes in many different directions (not just straight down or straight forward) more accurately with fewer misses, something a heavy single-purpose framing hammer did not do well. They knew how to avoid wasted motion and time. They knew about rhythm.

They were not what could be called kindly gentlemen, but looking back I prefer to imagine they were looking out for me when they barked “bring more 2×12’s, quick now dammit,” and “stop being a pain in the ass, kid.” Ah yes, good times!

They were prophets too when they warned me that the stresses I placed on my hands, arms, knees and back when I was young and dumb and full of something may not hurt at the time but would hurt every day many years later. It truly pains me to admit it, but those crusty old farts just might have been right.

So in memory of those curmudgeonly carpenters now sorting boards in the big lumberyard in the sky, let me summarize three pieces of profound wisdom they taught me. Do with them as you will. If you still have room, you might want to add them to that forehead tattoo you’ve got going (ツ)。

First, strive to use your hammer efficiently with minimum force, minimum wasted motion, and minimum stress on joints and tendons. Or as the old boys put it: “less swingin more hittin.”

Second, use an efficient hammer of the right type and weight that will get the job done without damaging your joints and tendons.

And third, stop being a pain in the ass.

Just be thankful that I am kinder than those crusty critters were and will tell you clearly in words what they communicated to me only with grunts, curses and boots while chewing on stogies and chortling as they watched me struggle with concrete form-work 18 feet in the air like the proverbial amorous monkey with his football. Yes, love was in the air…

Indeed, just to prove what a sweetheart I am, here are two more pieces of detailed advice specifically related to hammers: First, determine the style of hammer and weight that works best for you and the work situation. This will take experimentation.

Second, make handles for your hammers that suit your body and the combined natural frequency and the work you use them for instead of settling for the usual one-size-fits-nobody hammers hanging like noxious neon-colored plastic fruit on the walls of big-box retailers.

This last point will be the subject of another series of future articles.

That forehead tattoo is down past your chin by now, I suppose. （ツ）

Series Summary

For such a simple subject this series has been rather long. Let me summarize what you should take away:

Use a steel hammer to strike Japanese chisels instead of a mallet made of wood, rawhide, rubber, plastic or brass;
Use a hammer with a flat, polished face to strike your C&S Tool’s chisels for greater work efficiency and increased tool longevity;
Through experimentation, determine and use the hammer weight(s) that best compliments the chisel’s weight and width, the hardness of the wood, and the natural frequency of your hand and arm;
Make a handle for your hammer that follows sound ergonomic principles (versus marketing hype), fits your body, and helps you work with greater speed and precision. This series of posts about designing and making a handle should help;
Less swingin more cuttin;
Cut the wood with a sharp blade instead of beating it to slivers and prying them out with a sharpened screwdriver;
Control your chisel’s depth of cut to prevent your chisel’s cutting edge from binding in the wood, slowing the work down, and becoming dull early;
Do the “chisel cha-cha” but never the “chisel wiggle;” Just don’t.
Don’t use the chisel to lever out jammed-in waste, but instead flick loose waste out of joints with a quick twist of your wrist without slowing down or setting aside chisel or hammer;
Work to a rhythm to maintain your cutting pace and focus.

Thank you for reading this series of articles. Until we meet around the water can next, I have the singular honor to remain,

YMHOS

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 by using 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 my forehead tattoos merge.

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Hammers to Use With Chisels Part 5 – Rhythm & Song

A masterpiece goban made in 1910 from a single block of wood. Overall height: 29cm (11.4″); 45.2×42.4cm (17.8″square) x thickness: 16.1cm (6.3″). This is the old style goban and a little smaller than modern models.

This life’s hard, but it’s harder if you’re stupid.
George V. Higgins, The Friends of Eddie Coyle

In previous articles in this series about the characteristics of the hammers Beloved Customer should use with C&S Tools’ chisels, we looked at factors such as the type of hammer, the sort of face it should have and how much it should weigh. We even examined ways to use our chisels and hammers as an efficient but dangerous team when cutting mortises, and how to avoid the dreaded chisel wiggle. Your humble servant trusts it was a footloose and gleeful read.

This time your humble servant will delve a little deeper into how to deploy a hammer and chisel team.

The photos above and below are of gameboards, and while gameboards are not really the subject of this post, these photos illustrate an aspect of precise work with chisel and hammer intended not to create a shape to please the eye, but an artistic sound to improve concentration. Perhaps you never have thought about using a chisel to make beautiful sounds, but many of our Beloved Customers that make musical instruments professionally are focused like a laser on this very objective. I hope you will find this little article amusing.

The underside of the same goban. The legs are detachable with short square tenons fitting into loose mortises.

Natural Frequency

Much hammer and chisel work performed by professional woodworkers is repetitive with motions repeated thousands of times in a single day, each motion consuming time and energy, hopefully with precision and speed. Are time, energy, precision, and speed important to you? I propose that “Sure and steady wins the race,” sooner and more efficiently than a 2lb steel woodpecker on meth. If these factors matter not to you, then let me know and I will include some colorful bubblewrap in your next order for entertainment purposes.

If you studied pendulums and harmonic motion in physics classes you are aware that every moving object, from watch balances, to buildings, to mountain ranges (yes, mountains wiggle) have a natural “frequency” that defines the vibration of that object when subjected to specific forces. This reliable characteristic is why both mechanical clocks and a quartz crystal timepieces can keep accurate time. Like the pendulum in a grandfather clock, within a certain range of energy input, the longer and heavier an object is, the longer it’s natural frequency is likely to be.

In the case of hammer work this means that a man with a long, heavy arm and hammer combination will naturally swing a hammer cyclically slower than a man with a shorter, lighter arm/hammer combination. That does not mean one is better than the other, it just means that an arm/hammer combination will work most effectively if the assembly’s natural frequency is worked with instead of fought against.

There are several ways to reliably adjust this natural frequency, for instance changing the weight of the hammer/chisel combination, or changing the length of the hammer handle. The closer the hammer’s weight and length are to the ideal for a particular arm/chisel/wood combination the easier it becomes for us to consistently adjust the assembly’s frequency and rhythm of the cutting process while controlling the impact force and thereby the depth of cut.

Rhythm

So let’s say we have the hammer/chisel/wood/arm combination (or saw/wood/arm combination) where we need it to be and we start cutting wood in a repetitive motion. If we keep this motion consistent, like a clock pendulum, we will develop what in music is called “rhythm,” a phenomenon deeply rooted in the human beast. Rhythm is critical to cutting speed and precision. Anything that breaks that rhythm other than the job being completed is counterproductive.

Rhythm has psychological benefits too because it helps us to maintain focus and thereby accomplish more work quicker and more consistently.

But how does one maintain rhythm when cutting mortises? Perhaps you have an internal metronome. If not, it may help to take advantage of an extremely ancient tool called the “work song,” later called the “sea shanty.” These were songs sung by men and women working in groups to coordinate and make more efficient their physical labor, whether planting rice seedlings in flooded fields, pushing wagons over mountains, dragging logs through forests, or pulling soggy ship anchors up from the depths. If the song is in your head instead of just your ear you can easily adjust the song’s rhythm to match the natural frequency of your body and your tools.

I hum a work song when I do repetitive chisel work. I suppose three of my favorites are “What will we do with drunken sailor,” “The Wellerman,” and “Roll the Old Chariot Along.” There are also lots of old plantation and work gang songs that work well. Three modern tunes I find myself humming sometimes are “Señorita,” “Havana” and “Poker Face,” depending on my mood. Here is another, more unusual version by an entertaining German polka band.

While the six songs listed above certainly illustrate the exquisitely refined taste in music your servants at C&S Tools possess in buckets and barrels, there are a few points I need to make. First, the words don’t matter at all. Second, the tune doesn’t matter so long as you like it, it isn’t tedious, and you can adjust the tempo in your mind’s ear to help maintain the rhythm of your chisel work. And third, Spanish-language novellas are best avoided. (ツ）

Just so there’s no confusion, unlike Miss Germanotta, I don’t wear a sequin bikini and white Gestapo hat when I hum Poker Face while sawing wood or chopping scarf joints. If I shaved my legs and trimmed my beard I am confident I would look devastating in such an outfit, but I must refrain for some of my chisels are quite sensitive in matters of decorum. Don’t hate me because I’m beautiful (ツ)。

Summary

The main points I wanted to make in this article can be summarized as follows:

Whether you realize it or not, your chisel, hammer, and body have a natural frequency that you can either work with to your advantage, or fight against;
Using the principles listed in earlier posts in this series you can develop a chisel/hammer combination that balances well with your body, adjusting your natural frequency to improve your productivity and precision;
Develop a rhythm when doing repetitive work that compliments your natural frequency and that helps you maintain both focus and a steady wood-eating pace. Work songs really help. Sequin bikini, Ray Bans, and facial iron mongery are optional.

Well that’s enough German polka music and doggie apparel for now. In the final article in this series we will examine some health matters related to hammers. Y’all come back now, y’hear.

YMHOS

The traditional Japanese roof structure. Notice that no members are subject to tension forces, only compression and bending. Notice also that the bottom of the central beam is finished with just an adze in the classical “naguri” style.

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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Hammers to Use With Chisels Part 4 – The Chisel Cha-Cha

Your Most Humble and Obedient Servant hard at work. A dab of skin lotion may be called for.

You can lead a horse to water, but a pencil must be led.
Stan Laurel

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 guidelines. In this article we will examine some important hammer and chisel techniques Beloved Customer should consider to make your chisel work more efficient and 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 with their soft-as-butta chisels teach, but I unabashedly assert that it is irresponsible behavior 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” situation, 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 wedged-in-place 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, plasticy 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 tough but 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 anyway so I have no advice for those poor benighted souls, only prayers: Namu Amida Butsu. But it is of little matter because they seldom have the sharpening and tool skills required to tell the difference. 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: There are at least three techniques the efficient craftsman should employ, or at least develop skills adequate to deploy, when cutting joints in wood:

Limit the amount of wood included in each cut to an amount easily and quickly cut and easily and quickly removed. Strict control of one’s inner-badger is required;
Stop striking the chisel with hammer during each cut just before the chisel binds in a high-pressure situation, or just before waste clogs the joint. Once again, control of one’s impertinent inner-badger is essential, and the consumption of buckets of methamphetamine is not recommended when performing chisel work.
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 without any silly levering.

And Voila! No time lost extracting a stuck blade or setting down and picking up your hammer and repositioning your grip on the chisel. And the cutting work can continue uninterrupted without the wasted time and effort of extracting a bound chisel all while avoiding a damaged cutting edge.

It’s 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. I call this series of controlled movements the “ chisel cha cha.”

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 efficient and sophisticated chisel cha-cha is to avoid banging the chisel into the cut too deeply/tightly and to limit the waste made with each cut to an easily-removable amount. To dance this dance you need to stop hammering just before the blade binds in the cut, precisely controlling the depth to which your hammer drives your chisel. 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? Of necessity it varies with the chisel, the type of cut being made, the nature of the wood being cut, 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.

Summary

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, demands wasteful movements like setting down your hammer to extract it;
Use your sharp chisel for cutting wood, not as a crowbar for levering out waste. Instead, use your sharp blade to quickly 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.

With this, there is nothing to stop you, your hammer, and your chisel from performing as a precise and graceful, but oh so violent team, so shall we dance!

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,

YMHOS

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.

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Hammers to Use With Chisels Part 3 – Hammer Weight

Top: 375gm Yamakichi gennou head by Hiroki with new osage orange handle. Bottom: Ryoguchi-style gennou head by Kosaburo with a seasoned handle of the same osage orange. This same hammer was shown in Part 1 of this series when it was fresh and nuclear-flash yellow. With time and exposure to sunlight the color has changed to this pleasant brown. Thanks Matt for the OO!

“All that is gold does not glitter,

Not all those who wander are lost;

The old that is strong does not wither,

Deep roots are not reached by the frost.

From the ashes a fire shall be woken,

A light from the shadows shall spring;

Renewed shall be blade that was broken,

The crownless again shall be king.
J.R.R. Tolkien, The Fellowship of the Ring

In previous articles in this series about hammers to use with our chisels, your most humble and obedient servant discussed the varieties of hammers and the types of faces suitable for using with our chisels. In this article we will examine not only hammer weights but other factors to help your chisel work go more efficiently.

Beater & Beatee

You can usually tell when a hammer is too light for the job because the chisel or nail isn’t moved much and the beater bounces off. But it’s the other end of the weight scale that causes more serious problems so let’s consider the case of too heavy hammers so we can bracket the Goldilocks weight: Not too heavy, not too light, but just right.

Some people like to use heavy hammers for striking chisels. 2~3-lb ox-killers are good for some jobs, but there are a few things you should consider before defaulting too such a heavy lump.

Is the impact force produced by a heavy hammer really necessary to drive a chisel? Too often not so much. But not everything we do must focus exclusively on efficiency: swinging a hammer is good exercise and it burns calories, something those with excess “ dignity,” such as your humble servant, could use more of. However, in light of other factors discussed below, I urge you to resist the natural compulsion to remain one of the “beautiful people” by maintaining at all costs a sylphlike figure worthy of Paris Fashion Week by obsessively using overly-heavy hammers. Relax, for you already look mahvelous, darling, absolutely mahvelous!

Besides the herculean strength of your mighty arm and the chisel’s durability, Gentle Reader should also consider the durability of your body. Swinging a hammer that is too heavy can over-stress muscles, tendons, bones and joints, stresses that can make workdays long, nights painful and your work sloppy, if not now then certainly as you age. More on that subject in a future article.

But if the weight of the head is a good balance with the work you are doing, and you have a good handle on your hammer or gennou, things just go better. We will look at this more in the final post in this series.

Let’s start at the beginning and consider the movement of the hammer and the forces generated when accelerating it towards nail or chisel and the resulting stresses produced in muscles, tendons, bones and joints. Obviously, it is wise to keep these stresses within acceptable limits, especially if you need to repeat this movement hundreds or even thousands of times in a day. It should likewise be obvious that a hammer that is overly heavy makes limiting these stresses difficult.

Now that we have the hammer moving, let’s examine what happens when it stops as it strikes nail or chisel. Is wacking the nail or chisel as hard as possible the goal, or is the goal to drive the nail into the wood the right depth, or to motivate the chisel to cut wood an appropriate distance? If the latter, then there is a practical limit to the impact force required.

In other words, does driving a nail so deeply the wood is damaged unnecessarily, or does wacking a chisel so hard it cuts all the way through the board, or even binds in the wood, help us do better work?

Are the excessive stresses and vibrations flowing and slamming through one’s joints and tendons as a result of the violent acceleration, deceleration and impact forces generated when swinging an overweight hammer healthy and helpful? Or do they just waste energy, damage our work product, cause bruising, pinching, grinding and numbness and generally wear out hands and arms? Do these excessive stresses and vibrations improve our precision?

The positive and negative results of using a hammer are easier to control if the hammer’s weight is balanced with our bodies, the nail or chisel, and the wood.

Another factor to consider is the nature of the beatee. Nails often suffer from hammer abuse, but they don’t have feelings or form mutual support groups with monthly meetings and free coffee and donuts, while chisels do, so I encourage you be sensitive to your chisel’s needs when selecting a hammer weight. Oh, and don’t forget to donate a box of fresh donuts occasionally (with sprinkles).

Our chisels are hand-made professional-grade tools intended to be used by craftsmen who demand the extra sharpness and cutting longevity only hard, fine-grained steel makes possible. Therefore they are not as tough as the soft, sharpened Chinese screwdrivers sold by the big corporations as chisels that amateurs are accustomed to nowadays. Accordingly you should select a hammer weight that won’t damage the blades or splinter the handles of your fine chisels even if you must use them all day for days on end hard enough for the impact forces to make the handles hot. You may be as strong as John Henry, but a 2-lb hammer will destroy most any chisel given time and determination.

Weighty Matters

Of course, the harder the wood, the deeper the cut, the wider and heavier the chisel, the heavier the hammer needed. But what is an efficient hammer weight? Let’s consider some guidelines.

Oiirenomi & Mukomachinomi Chisels

For most commercially-available woods you are likely to cut with your oiirenomi chisels or mukomachinomi (mortise chisel), 260gm/9oz/70monme is a good place to start when using narrower width chisels 18mm and less.

300gm (10.5oz/80monme) to 375gm (14oz/100monme) is probably good for wider chisels. BTW the standard carpenter’s hammer in Japan weighs between 375gm (14oz/100monme) to 450gm (16oz/120monme), but this is too heavy for most precision work using oiirenomi in furniture, cabinets, and joinery work.

Atsunomi Chisels

For the heavier atsunomi chisels from 18mm to 24mm in width, 375gm (14oz/100monme) ~ 450gm (16oz/120monme) is usually a good weight.

For wider atsunomi chisels, 675gm (24oz/180monme) to 750gm (26oz/200monme) is good. Maybe as heavy as 937gm (32oz/250monme) for motivating wide 48-54mm chisels when cutting hard woods if you have experience, strong wrists, and speed is not important. Yes, within limits and with a good handle, lighter weight hammers tend to accomplish more work quicker.

As Captain Barbossa explained the Pirate’s Code, these are “more what you’d call “guidelines” than actual rules.”

In future posts in this series we will examine factors such as how to use hammers and chisels efficiently, and how to avoid injuries.

Until then, I have the honor to remain,

YMHOS

PS: We have also published another series of articles about making a handle for your hammer that fits your body and will work most efficiently for you, beginning HERE. So let’s talk some more soon.

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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Hammers to Use With Chisels Part 2 – Hammer Faces

The Jabberwock! Not just a beautiful face.

Beware the Jabberwock, my son!
The jaws that bite, the claws that catch!
Beware the Jubjub bird, and shun
The frumious Bandersnatch!
Lewis Carroll

This is the second post in our six-part series about hammers to use with our chisels. As with all the tool-related articles we publish, this one is based on past communications with, and in response to direct questions from, our Beloved Customers. Your humble servant hopes that not only Beloved Customers (may the hair on their toes never fall out) but Gentle Readers too may gain something from these articles.

We sell limited quantities of hand-forged professional-grade chisels to professionals who use them to please their customers and feed their families.

We are tickled pink when amateurs purchase our products, but our target customer is the experienced professional woodworker. If you do your part our chisels will provide faithful, reliable service until, after many decades, nothing is left of the blade but a nub. But to achieve this longevity, and to avoid smiles turning upside down, we insist Beloved Customers use flat-faced hammers to motivate our chisels as a condition of our warranty. It’s that important, at least for the professional that uses his chisel even after the blade and handle become hot.

375gm gennou by Kosaburo with a black Persimmon handle resting on a Go board. The head is a classical style seldom seen nowadays.

In the previous post in this series we looked at the Japanese gennou hammer with its two faces: one domed and the other flat. In this post we will examine these two styles of hammer faces in more detail. We will leave waffle-faces to the Belgians for now.

The Domed Hammer Face

Few people in industrialized countries outside of Japan have any experience with flat-faced hammers since manufacturers automatically grind a convex or domed striking face on their hammers nowadays. It’s simply what consumers are accustomed too. But I daresay few have ever considered the ramifications of the dome.

Does the domed face on this standard 16oz American finish hammer look centered to you? Does it look smooth?

A domed face on a hammer has some advantages, of course. For instance, when one needs to “set” a nail with its head just below the flat surface of the piece of wood into which the nail is driven. But does a domed face help the hammer drive nails faster or straighter? Does it help reduce the ratio of bent nails to straight nails? Does it motivate chisels more efficiently? No, no and no.

Another more questionable feature of the domed face (depending on your viewpoint) is that it makes it difficult to judge the accuracy of one’s alignment of the centerpoint of the domed face and with the centerline of the hammer head. Who, pray tell, profits from this ambivalent construction? I’ll give you one guess, and it ain’t me or thee.

Indeed, if your working hammer tends to bend a lot of nails, I recommend you carefully examine its face with a square for centricity and uniformity. “Doh! (palm to forehead). No frikin wonder,” may well be your genteel reaction.

While it may seem passing strange, we strongly recommend Beloved Customers use a hammer with a flat striking face to motivate our oiirenomi chisels, atsunomi chisels, and mortise chisels.

So why is a domed-face hammer a problem when striking Japanese chisels? Simply because it tends to focus the impact forces on a relatively smaller area on the wooden handle than a flat-faced hammer does accelerating wear on, and shortening the life of, the handle.

In addition, and especially if you are skilled at hitting the handle dead-center a high percentage of the time, a domed face will actually encourage the mild-steel crown to try to jump off the handle whereupon the steel hammer gleefully beats the crown and deforms it, often to the point where the deformed crown itself may damage the handle. Yes, this takes some time, but it happens frequently, a wasteful tragedy that can be avoided by using a hammer with a flat face and some simple setup procedures.

The Flat Hammer Face

While your humble servant is inordinately fond of the Japanese gennou hammer, it is by no means the only viable option. Indeed, you can easily modify most any decent-quality, properly-hardened hammer to have a flat face by simply abrading it with a grinder or sander.

Be sure you make the new face planar (flat) and truly square to the hammer’s centerline because a tilt to the left or right will make doing precise work inexplicably difficult and may lead to insanity. I once knew a “frugal” carpenter (read “cheap jackass”) who insisted on using a hammer with a skewampus face. The cumulative corrosion to his confidence caused his wits to wander into the weeds (iambic pentameter?). A sad story but one, I am told, that is commonly heard at AA meetings.

If you are modifying a standard hammer with a standard handle, you may benefit from tilting the face’s plane a bit inwards towards the handle, but there is not adequate space in this post to discuss this modification in detail.

Whatever you do, be especially careful to avoid overheating the hammer’s face while grinding/sanding it; Too hot and the temper will be damaged softening the hammer’s face and ruining it. Seriously. Even a wooden chisel handle will eventually mushroom a steel hammer that has lost its temper.

Here’s a guideline: If the hammer’s face becomes too hot to touch with your bare finger, its temper is at serious risk.

Finally, once the face is as flat and square and smooth as you can make it with your grinder or sander, be sure to polish the face because a smooth face wears out the chisel handle slower. A final polish with 320 grit W/D sandpaper is adequate. We polish ours even finer on sharpening stones. Overkill? Yup. Why bother? Because we like purty hammers and they deserve our love. Don’t worry, the polish won’t make the hammer’s face slippery, unless you imitate Mr. March Hare and spread butter on it.

By the way, once your flat-face hammer is ready, try driving nails with it. You will find it works a lot better for everything except setting nailheads below the board’s face. A nailset works better for that job anyway.

We hope our Beloved Customers will take this article to heart for the sake of their chisels.

Summary

In this post we reviewed two types of hammer faces: domed and flat. We also considered the advantages and disadvantages of each, and explained why a flat face is best for beating on Japanese chisels, and gave an example of the brutish damage a domed face can inflict on a poor innocent chisel. Like me, some of you may have shed a tear at the sight, but I bid you take heart because we also instructed you in how to convert a common domed-face hammer of any sort to a more genteel, polished, flat-faced hammer at no cost, one that will also drive nails better without butter. O frabjous day! Callooh! Callay!

To motivate chisels efficiently, the hammer must not only have a flat face, but it must be of the appropriate weight. Of course, the harder the wood, the deeper the cut, the wider and heavier the chisel, the heavier the hammer needed. But what is an efficient hammer weight? We will examine some options in the next post in this series. Please stay tuned, my beamish boy.

Until then, I have the honor to remain,

YMHOS

A hand-forged square gennou head by Hiroki with a handle made from a traditional Japanese handle wood called “Kamatsu” (Pourthiaea villosa) meaning “sickle handle, also called “Ushikoroshi (“cow killer”). Despite the appearance, the head is one-piece of uniform steel, not a jigane body with forge-welded steel faces. BTW, if someone tells you that hammers with forge-welded faces are superior, direct them to the closest legal marijuana dispensary so they can maintain their waking psychotic dreams.

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.

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Hammers to Use With Chisels Part 1 – Hammer Varieties

A modern-style 750gm gennou head hand-forged by Kosaburo, hung with a black persimmon handle. I purchased this high-quality head over 33 years ago. An heirloom tool and a good buddy.

Yet such is oft the course of deeds that move the wheels of the world: small hands do them because they must, while the eyes of the great are elsewhere.
Elrond

This is the first article in a six-part series that condenses the advice your humble servant has given to our Beloved Customers over the years regarding the hammers they should use with our chisels. While some of this information is relevant to our warranty, all of it is relevant to how well our chisels will perform and the pleasure Beloved Customers will enjoy using them.

In this first part we will focus on the varieties of hammers we recommend. Subsequent articles in this series will focus on appropriate hammer weights and faces, how to use a chisel efficiently, the “chisel cha-cha,” the importance of rhythm, as well as a discussion about health and hammers. There may even be a song or two to hum along with. Helluvalot better than a performance of Cats, and cheaper too!

In the future we will present several different series, one with more details about hammer heads, and another explaining why and describing how to make a handle for a Japanese gennou hammer (or any hammer for that matter), with scaled reference drawings. We will of course provide the entire contents of these articles wrapped up in a happy wiggling bundle to Beloved Customers that purchase one of our gennou heads. Yes, there are more perks to being a Beloved Customer than simple toe-curling joy (ツ）。As Blackadder’s little buddy Baldrick often said: ” I have a cunning plan.”

Hammer Materials

We sell tatakinomi chisels such as oiirenomi, hantataki chisels, mukomachinomi (mortise chisels), or atsunomi all designed to be motivated by the most efficient method available, namely a steel hammer swung by human hand and arm. I won’t debate the pros/cons of steel hammers versus wooden mallets versus plastic mallets versus brass hammers in this post because the physics are as obvious as a lemur in a lingerie shop (they’re a bit hairy, they jump and climb all over the displays and bra straps are forever slipping off their skinny shoulders, but not in a seductive manner!) beyond noting that a hardened steel hammer imparts more energy to a chisel in a more easily focused and controllable manner than any other type of beater. Some may disagree; A mind is a terrible thing to taste.

Occasionally Gentle Readers, and sometimes even Beloved Customers, ask if it’s OK to use a mallet of wood or plastic. Of course, it’s entirely acceptable, but no more necessary in the case of our professional-grade chisels than a speed governor set at 45mph is in a Ferrari.

The advantages of using a steel hammer to motivate chisels are quite obvious, even without doing energy calculations, but are there any disadvantages? Mochiron (Japanese for “of course”).

Steel hammers can concentrate so much energy on a tool handle so efficiently and so quickly that they routinely destroy the handles of the sharpened screwdrivers sold as chisels nowadays in Western countries due to faulty handle design.

At this point, wise Gentle Reader will ask themself why the handles of modern chisels are so fragile. Is it just an accident? If intentional, is modern wood softer and easier to cut than wood a few hundred years ago? Or has modern man become demented forgetting all the lessons of the past regarding chisel design, just as some have forgotten what the word “woman” means?

While dementia, sexual perversion and corruption among the leaders of the nations is obviously a serious problem nowadays, it is likely many marketing gurus, e-commerce pukes and cad operators never learned much about the tools they manufacture and sell. It’s also as obvious as lingerie on a lemur that most modern chisels are designed not to provide good service but rather to maximize profits through: (1) Lowest possible manufacturing costs; (2) Attractive appearance while hanging on hooks in the hardware store; and (3) Future purchases to replace chisels with broken handles, in other words, a cheap, eye-catching product incorporating planned obsolescence.

Prosimians flouncing around in lacy unmentionables aside, the tataki nomi chisels we sell are professional-grade tools designed to be struck by hardened-steel flat-faced hammers all day long and need not be coddled. They have tough Japanese oak handles protected by a cleverly-designed mild-steel kuchigane (coned ferrule) fitted where the handle meets the blade, and a mild-steel hoop, or crown, seated at the butt end of the handle, so they will not split or break when setup and used properly.

We have provided clear instructions for how to perform this setup job here.

But there is more to hammers than just materials, so let’s continue onto the next subject.

Japanese Hammer Types

A Kosaburo head with a brand-new nuclear-flash colored Osage Orange handle

The traditional hammer used in Eastern Japan for striking chisels and general carpentry work is called a “gennou” pronounced “ghen/noh.”

The gennou common to Eastern Japan is a simple symmetrical cylinder of one sort or another with a flat face on one end and a domed face on the other, often called the “ryoguchi gennou.” No claws, no pointy tail. The flat face is used for striking chisels and pounding nails. The domed face is used for something called “kigoroshi” and for the last stroke when setting nails. It’s a handy tool and more stable in the swing than a claw hammer. It’s just a matter of physics.

Japanese carpenters use a specialized nail bar for pulling nails effectively increasing the lifespan of their hammer handles, so claws are not necessary.

3 gennou heads. The far left head is a simple economy head. The center head is a higher-grade head slightly flared towards the ends. The far right head is an entirely hand-forged classic head by Kosaburo.

The Yamakichi style gennou head (see photo below) is another variety popular primarily in Western Japan. The tail is not pointy but tapers to a small square face that is useful for starting small nails and for “ tapping out” plane blades. The striking face typically has a slight curvature which is helpful for setting nails, but not enough to damage a chisel. The moment of inertia is less than the symmetrical gennou head so it is not as stable in the swing, but it is still a fine head and very sexy looking.

A “Yamakichi” style head by *Hiroki* with a mellowed Osage Orange handle

The pictures below are of a gennou head called “Funate,” which translates to “boat hand.” I have heard it originated with ship carpenters, but am uncertain. The tail end is a small square as you can see from the photo, and is handy for setting nails. It makes a great finish hammer, but as a hammer for striking gennou it never appealed to me. But there are plenty of craftsmen that love this hammer.

Any of these hammers will do the job: it’s all personal preference.

Western Hammer Types

The purpose of this article is is not to suggest that Beloved Customers must use a Japanese gennou hammer when beating on our chisels. In fact, nearly any variety of quality steel hammer can be easily modified to do the job more-or-less satisfactorily, including claw hammers, engineer’s hammers, warrington hammers, or even ball peen hammers, so it isn’t necessary to buy a special hammer. In fact, we’ll discuss those modifications in detail as well as the relevant physics of hammers in future articles in this series. Rejoice for there will be formulas!

In the next post in this series we will examine the type of face a hammer used to strike our chisels should have. Please come back and bring your fuzzy primate friends.

YMHOS

Do you have something extra-slinky with red Chantilly lace trim?

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Varieties of Gennou: Ryouguchi Gennou

Varieties of Gennou: Kataguchi Gennou

The Varieties of Gennou: Daruma Gennou

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Previous Posts in The Japanese Gennou Hammer & Handle Series

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What Is a Gennou?

The Attraction of the Gennou

Why Use a Gennou for Chiselwork?

Technical Matters

Irregularities

Correcting Irregularities

The Pig’s Ear

The Flawed Face

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Previous Posts in The Japanese Gennou Hammer & Handle Series

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Ergonomic Factors

Three Questions

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Previous Posts in The Japanese Gennou & Handle Series

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Introduction

The True Craftsman Makes His Own Tools

Modern Tools: Marketing, Design & Manufacturing

Hammer Handle Morphology

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Subsequent Posts in The Japanese Gennou & Handle Series

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Health Matters

Series Summary

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Natural Frequency

Rhythm

Summary

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The Chisel Wiggle

The Chisel Cha-Cha

The Dance of the Hammer and the Chisel

Summary

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Beater & Beatee

Weighty Matters

Oiirenomi & Mukomachinomi Chisels

Atsunomi Chisels

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The Domed Hammer Face

The Flat Hammer Face

Summary

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Hammer Materials

Japanese Hammer Types

Western Hammer Types

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