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

What we have is given by God and to teach it to others is to return it to him.

Gian Lorenzo Bernini
56-1
Kiyomizu Temple, Kyoto, Japan

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 crushing wood (i.e. “kigoroshi” or “wood killing”). This article will provide a further introduction to the gennou hammer.

What Is a Gennou?

A box-stock, garden-variety, economy 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.” The gennou (pronounced gen-noh), on the other hand, can be used to drive nails, but it is also suited to striking chisels and adjusting planes. The word genno 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 often have an emotional attachment to their gennou. Perhaps this is because, unlike saws, chisels, and planes that are gradually but inevitably sharpened away until almost nothing remains, or squares or making gauges that loose tolerance 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 pigtail; It doesn’t need to be sharpened. And most importantly, it will never ask a dangerous question like “do these pants make my butt look big?”

Technical Matters

The gennou is a simple tool consisting of a steel body of some shape or another and a wooden handle. The head has a rectangular hole called the “eye” in English and “hitsu” in Japanese to receive the handle’s tenon. A high-quality gennou with a good eye and a handle made by a skilled craftsman doesn’t have wedges or other silly contrivances to connect the two.

The steel used is typically designated SK, a standard high-carbon tool steel made in Japan used for making hammers, axes, and many other tools. It is very similar chemically speaking to 01 steel in the Americas. Not as pure as Hitachi Metal’s Shirogami or Aogami steel, but still completely adequate for hammers. I wouldn’t pay extra for a gennou head made from Shirogami or Aogami steel, and you shouldn’t either

Mass-produced gennou are 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. A gennou head with rough and/or irregular eyes can create unnecessary problems for the user.

“Irregular” has several connotations when talking about gennou eyes. One obvious problem is an eye that is not truly rectangular. For instance, it may have curved, twisted walls, wonky interior dimensions, or interior corners that are not square. Not only is it a pain in the tuckus to make a handle to fit an eye with these deformities, but you can bet your sweet bippy it will 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 hold onto the tenon better, and perhaps they do compared to highly-polished walls, but rough, uneven walls tend to wear-out the tenon and cause it to loosen over time. Imagine the vibrations the tenon is forced to absorb through those walls and the grinding motion between wall surface and handle that results.

An intentional irregularity frequently seen 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 in the 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 is a reasonable solution for rough, irregular eyes in low-cost hammers to be used by amateurs, but one that the craftsman that truly understands gennou and wants a lifetime tool finds undesireable. 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 skewampus couldn’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 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.

I hate to say it, but our Beloved Customers should watch out for 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 knowledgable professional woodworkers in Japan for occasionally making 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 be a pig. If you cannot hold and eyeball an expensive gennou head before concluding the transaction, at least make sure you purchase from someone with a solid guarantee.

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.

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 handle. The solution in the West in the last century 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 for striking a chisel with a hammer is to drive the chisel into and through the wood by cutting it, right? But a soft-faced wooden mallet deforms when it impacts the chisel cushioning the blow and wasting energy through this deformation as well as generated heat. It may also 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 mallet is bulkier, slower to swing, has a huge face, and is therefore less precise than a smaller steel hammer. 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 sacrifice 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.

Ise jingu Shrine, Mie Prefecture, Japan

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 have never tolerated such silly nonsense as a chisel that must be coddled, and quite early developed a wooden-handled chisel that can be struck hard with a steel hammer all day long without breaking. 

When using a Japanese striking chisel (versus a push or paring chisel) with a hard steel hammer, as much of the user’s energy and time as possible goes into actually cutting wood. The same cannot be said of mallets made of wood, rawhide, or plastic.

The excellent design of the Japanese chisel combined with the quality of steel, and the forging 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. As the Japanese are wont to do, they developed a hammer specifically for striking chisels.

Most hammers intended for driving nails have a domed face which does not work well with Japanese chisels because it tends to dish out the end of the handle causing the hoop to loosen. This can even result in the handle cracking or splitting. A flat-faced hammer is much better. The Japanese double-faced genno has one face that is forged flat, for striking chisels, and an opposing domed face for driving nails or performing “kigoroshi.”

The simplicity of the design combined with these two types of faces are the primary reasons we recommend using the gennou for motivating chisels.

And while one could grind the face of a Western claw hammer flat and use it to strike Japanese chisels without any problems, the gennou is a hammer that is designed specifically for striking chisels. In my 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

Pagoda at Horyuji Temple, registered as one of Japan’s National Treasures, built using gennou.

If you have questions or would like to learn more about our tools, please use the questions 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 or incompetent facebook and so won’t sell, “share,” or profitably “misplace” your information.

Previous Posts in The Japanese Gennou & Handle Series

Part 1 – Introduction

Part 2 – Ergonomics

Toolchests Part 2 – History

Advice is a dangerous gift, even from the wise to the wise, and all courses may run ill.

J.R.R. Tolkien, The Fellowship of the Ring
An Egyptian Chest with very warlike decoration of chariots with archers, the main battle tank of the ancient world. What did the boy king store in it?

This is the second part of this series about toolchests. In this post, just to ensure we have a common understanding, we will examine some of the history and roles of chests in general.

The wooden chest is perhaps the most ancient hard-sided container used by humankind. This fact alone makes it a method of tool storage you should at least consider.

The traditional chest is simply a box with a lid. Throughout human history, most chests have been made of wood, although there are examples made of rushes, stone and metal.

It has 4 fixed sides, a fixed bottom, and an operable lid on top. Some have legs of one type or another, others don’t. Some have drawers, but historically most did not. There are many ways to construct them, some materials and methods were better than others. There are even a few examples of nordic chests made by hollowing-out logs.

A Scandinavian chest made from a section of tree trunk
Another antique chest made form a section of a tree trunk

Since at least the bronze age, chests used by common folk were expected to provide more than just storage space, but to do double, even triple duty as tables, benches, beds, food storage, food processing equipment and sometimes even fortifications.

Small Medieval oak ironbound chest, clamp front in construction and the iron work consists of flat straps with fleur-de-lys motifs and a large butterfly lock plate. Origin: Germany Date: Circa 1400 Dimensions: Width (inches) 36 1/2 x Height 21 3/4 x Depth 16

For millennia chests were used to house and protect clothes, blankets, linens, armor, weapons, boots, horse gear, cooking and eating utensils, food, and money, just to name a few categories. Nowadays we tend to think of chests as storage space for clothing and blankets, or as a bench seat placed at the foot of a bed, but they were also practical household tools used to store grain in hovels shared with livestock and lit by rush lights when candles were a prohibitively expensive luxury. The inverted lid of these “grain arks” were used as a trough for kneading bread dough after the goodwife had turned the winnowed grain into meal during her “daily grind.”

An English oak clamped-front ark  17th century the canted boarded detachable cover above a twin panelled front and later filled lockplate, with channelled stiles
A medieval clamp-construction “grain ark.” A household’s goodwife would store her grain in this chest. The lid can be rotated open, but is not “hinged,” per-say. The goodwife would use a quern stone to grind the grain into flour, usually of a rough consistency. This is where the term “daily grind” originated. She would then turn the grain ark’s lid upside down, rest it on the base, and use the trough formed to knead the dough to make the “daily bread.” When done, the lid was cleaned, turned upside down and placed on the base to as a lid once again protecting the grain from dust, water, bugs and vermin.
Milling Grain with Water Power
Quern stone used for grinding grain to make flour.
Using a quern stone to grind flour in the Czech Republic.

Chests can be simple, easy to make, relatively inexpensive, and very durable. Or they can be fabulously expensive pieces of high-art intended to communicate status and wealth, as many museum collections can attest. 

An early Renaissance, cassoni, or marriage chest. These were usually made in pairs and sent by the groom’s family to the bride to hold her dowry during the very public bridal procession, making them ostentatious signs of wealth and prestige if only for a few hours, days or weeks while in-transit.

Throughout history chests have been carved, painted, lacquered, covered with nails, inlaid with mother of pearl or chased metal, and even gilded with gold leaf. They’ve served as strong-boxes for crusader banks, transported Incan gold on Spanish galleons, and accompanied Italian princess loaded down with rich dowry goods. But whatever their purpose or appearance, chests were once the most common storage container in human civilization, with every well-established household throughout the world possessing at least one. Regardless of where you live now or where your forefathers originated, it is safe to say that thousands of chests served your ancestors down through history. The chest is older than the chair, and much older than the elevated bed. Only dirt has a longer track record.

Pennsylvania Dutch (German) dowry chest with painted unicorns and flower decoration.
A Zanzibar dowry chest with red paint and brass hardware and nails
Turkish Dowry Chest covered with mother-of-pearl inlay

Chests are not as ergonomic or convenient as modern cabinets, and for this reason and others have fallen out of fashion, but their utility is not diminished especially in the case of woodworking tools which do not wrinkle or molder.

There are many surviving examples of ancient toolchests we can learn from. Europe and the Middle-east are not the only sources of inspiration available.

A very traditional “Nagamochi” tansu from Japan. These were specifically designed for not only general storage, but for transporting goods during the periods of Japan’s history when animal-powered carts were forbidden to ordinary folk. The rectangular bit of hardware seen at the ends was rotated up and wooden yoke was passed through so that two or men could carry the chest on their shoulders.
アンティーク家具 古民具 骨董 江戸時代 味の良い車長持ち(時代箪笥)
Another traditional Japanese chest called a “kuruma dansu 車箪笥,” which translates to “wheeled chest.” It too has the same nagamochi hardware on each end. Japan has a long history of fires that destroyed entire cities on a regular basis, so one justification for this style of chest was it could be wheeled out of the house quickly before the house burnt down saving valuables. Try doing that with a wall cabinet! My chest borrowed from this traditional design, but subsituted modern materials and detachable wheels. I have no patience with tiny, fragile casters.

One of the first pieces of furniture a journeyman woodworker in centuries past would make was a toolchest to house his valuable tools. Accordingly, many old woodworking instruction books included designs for toolchests. One such book was the inspiration for my toolchest.

Based on statistical data, the vast majority of modern buildings have a useful lifespan of around 50 years. Furniture and casework is much less nowadays. While this mindset has been a reality, indeed has been celebrated for the last 80 years or so, it is a wasteful attitude I strongly dislike, one that diminishes the quality of our current existence, beggars civilization’s future, and stuffs landfills. I have no interest in making low-cost objects that self-destruct or that might embarrass me in the eyes of my descendants. Accordingly, I set the useful lifespan of objects I make for my own use at 200 years. There is an off-chance I won’t be around that long, but God willing and the creek don’t rise, I can be sure the things I make with my own hands will, including this toolchest. Do you have useful lifespan goals for your woodworking?

While there are many varieties, no piece of furniture has served humanity longer or better than the chest. If you value your woodworking tools and want a woodworking project that will have long-term value, the toolchest is a storage system you should at least consider.

An iron-bound chest for containing valuables, the ancient equivalent of a portable safe.

In the next post in this series on tool chests we will examine the goals and objectives you would be wise consider when designing a toolchest, as well as the challenges toolchests face in the real dirty world.

YMHOS

If you have questions or would like to learn more about our tools, please use the questions 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 or incompetent facebook and so won’t sell, share, or profitably “misplace” your information. We swears on the Precious.

Other Posts in this Series

Toolchests Part 1 – And Away We Go

Toolchests Part 1 – And Away We Go

And Awaaay We Go

No wise fish would go anywhere without a porpoise.

Lewis Carroll, Mock Turtle, Alice’s Adventures in Wonderland

Every woodworker has tools they need to store. The longer one is at it, and the wider one’s competent range of skills, the more tools one needs.

There are those who advocate owning minimal tools, as if owning many tools is an emotional burden and fewer tools is healthier. Perhaps they are suffering from Marie Kondo syndrome.

I have known old men like that. Guys that grew up during the Great Depression and learned to accomplish many tasks with few tools because they could not afford more. Accomplishing the job without adequate tools became a matter of pride to them. But often the quality of their work suffered.

Or perhaps these minimalists are like a guy I used to work with who owned a favorite pair of expensive loafers and wore them to the office, to the beach, and when camping. He even boasted about wearing them last year to climb Mount Fuji. He is wealthy but strangely proud of owning only one pair of shoes.

Last time I saw his shoes they were scuffed and ragged and didn’t look good with a suit, but he never wore business attire even when he should have. His shoes would suck big donkey donuts in the snow or mud so he didn’t venture into such environments. They didn’t have steel toes, so he had to ask someone else do his jobsite inspections for him. Sure he had fewer shoes, but because of that, he was limited in where he could go, what he could do, and how much he enjoyed those activities. Just another sort of strange obsession, I suppose.

I have a different sort of obsession that I suspect sprang from a time when I had little money, but couldn’t earn the money I needed because I couldn’t afford the necessary tools. A frustrating situation many of our Gentle Readers may also have experienced.

I enjoy the confidence being able to do many different kinds of physical work competently brings. Those skills are useful, however, only because I own the tools necessary to perform that work. Accordingly, I would never get rid of quality useful tools because to do so would mean I could no longer perform the type of work those tools are made for.

So I confess to owning lots of tools. Maybe I need a 12 step program.

I don’t leave my tools laying around in a rusty jumble or, heaven forbid, hanging on pegs in a dusty garage. I store them effectively so they will last and be ready to rock-n-roll when I need them. This, however, takes thought and preparation.

The purpose of my writing this is to share with you one effective solution to tool storage and usage. If even one of our Gentle Readers finds it helpful or even just amusing, then I will count my time writing this well spent.

My Toolchest. Built in Northern California 25+ years old from Honduras Mahogany

This series of posts will be a description of my toolchest, it’s design, and the goals, objectives and rational that drove the design and construction. I have also included some discussion about chests in general and toolchests in particular.

At this point, I can imagine many Gentle Readers rolling their eyes and saying to themselves: “Oh no, not another nitwit bragging about his toy box.” As the Arkansas horndog so often said with a slight crack in his compassionate voice: “I feel your pain.”

Related image
Meet Junior: Someday he’ll be President.

Much like proud parents posting pictures of their child’s alien-looking carrot puree-smeared visage on facebook to horrify the entire world, thousands of people have boasted about their toolchests online.

This is natural: Everyone is proud when a project is complete. We want to share our satisfaction with others at least partly because the accomplishment of the child reflects on the parent. But too often toolchest blogs are boring tales of unoriginal, unimproved, uninspiring designs and mediocre execution, so I don’t blame you if you suspect this just might be another such waste of time.

Considering past blogosphere disappointments, and the fact that even you, Gentle Reader (may you live forever), have limited time, I have worked hard to make this article informative and even useful with explanations, photographs, and even a roughly dimensioned drawing.

Of course, right now you are probably asking yourself “What qualifies this putz to write about toolchests and why should I bother to read it?” Good questions. No, I don’t mind the harsh language because I have often said the same thing to myself when reading toolchest blogs, albeit with great dignity and refinement (ツ). Allow me to explain.

The first qualification is that I know what I am talking about. No, I am not an author or teacher. I don’t even teach classes about making toolchests, and never will, the gods of handsaws willing. I am no longer a professional woodworker, but was for many years when people paid me to make durable, useful buildings, furniture and casework for them. Indeed, now I manage other people to make such items for my customers and am focused like a laser on design, performance, cost and time effectiveness, and quality.

The second qualification is that, while this toolchest has its roots in a traditional design, it is neither a copy of, nor does it purport to be “faithful” to, traditional designs, whatever the heck that means. It was born from original thinking to solve specific problems. Its design is neither accidental nor experimental.

I know how to manage the design of buildings and millwork costing many hundreds of millions of US dollars, and applied that experience to this design. Consequently, I considered, revised and improved each detail and dimension again and again over a period of several years even before buying the wood, and for good reasons. Of course, I continued to tweak the interior fitout and tool mounting methods during the years after it was completed, and repaired and repainted the outside after an attack by a rabid forklift, but the box is unchanged. I will explain those reasons and the resulting details and will share my conclusions with you. Then you, Gentle Reader (may the hair on your toes never fall out), may judge for yourself.

I am not suggesting that the decisions reflected in this toolchest are the best possible, and that you, Gentle Reader, should slavishly imitate them. Each Gentle Reader’s requirements are different. Their sensibilities are their own. Each must reach their own conclusions.

I read constantly, and believe I benefit from learning about other people’s solutions to the problems I face. I certainly learned from others before I designed and made this toolchest. Hopefully the information contained in this series of posts will help you make wise decisions in your woodworking.

Perhaps my most useful qualification for writing this are that I own very valuable, custom handmade tools I enjoy using and want to preserve. I also researched, built, and later tested this toolchest’s actual performance in housing those tools in several locations around the globe. So the results I will present here are not just a reproduction of historical examples, or one intended to photograph well for publication in a book or magazine. It is an original design with a track record of hard use in various climates around the world.

Indeed, this toolchest has not been sitting in one place for 25 years since I made it, but has followed me through multiple international relocations where it has been used and abused heavily, successfully passing multiple endurance tests. This track record sets this toolchest apart from most.

In this series of posts I will first touch on the definition of a toolchest, and the goals, objectives and rationale that drove the design. Next I’ll discuss the pros and cons of toolchests, and how to compensate for their inherent shortcomings. Then I will address the materials and construction of my toolchest followed by the finish I used.

I hope you will find this series interesting and perhaps even useful.

YMHOS

Touch me toolchest, matey, and I’ll pump ye full ‘o lead! Harghhh!

If you have questions or would like to learn more about our tools, please use the questions 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 or incompetent facebook and so won’t sell, share, or profitably “misplace” your information.

Other Post in the Toolchests Series

Toolchests Part 2 – History

The Japanese Gennou & Handle Part 2 – Ergonomics

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

Professor Marshall McLuhan
A Kosaburo hand-forged gennou head on a Black Persimmon handle

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 you 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 time I was a boy with a Daisy BB gun, I have enjoyed making beautiful rifle stocks using marbled walnut for my bolt-action guns and curly maple for flintlock longrifles. But a custom gunstock is not just a chunk of beautiful wood.

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 to provide a steadier hold, quicker target acquisition, and reduced recoil. These techniques work.

Indeed, there’s a surprising number of calculations one must crunch, measurements that must be made of the rifle’s components, and details of the user’s body that must be determined 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 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 1000 yard target bench 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 the hammer as a stupid tool lacking finesse, but I disagree. Let us consider some of the challenges the lowly hammer is expected to meet that an ergonomic design can help it overcome.

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. It adds up. This is just one reason why big-faced mallets are inefficient compared to a steel hammer. There are those who will revel in their ignorance by disputing this fact, but to them I say: There is no medicinal cure for stupidity so 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 D is the drag force, 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 D is the drag coefficient, a dimensionless number.

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

You don’t need to input actual numbers into this formula to see that the two factors in this equation we 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.

Second, when using our hammer we draw its head back beyond the range of our vision, and then, without looking, swing it with great force to precisely hit targets as small as a chisel handle or nail head, while avoiding hitting our own head, ear and hand. If the hammer’s head naughtily wiggles out of proper alignment during the swing, a headache or smashed finger may result, so we need a hammer head and handle combination that will be easy to keep in alignment during the swing without giving it a lot of 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 or 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 wanted it to cut in the opposite direction.

A person proficient in using mass-produced hammers must train their eye and body to match the hammer they are using at the moment. Of course, this can be done, but it is inefficient. What I am proposing instead is to design our hammer handles so they match our individual bodies and the work we need it to perform instead of being forced to adjust our grip and swing to fit standard one-size-fits-nobody design parameters.

A lot of blowhards and marketing departments give lip-service to so-called ergonomics, but not here at C&S Tools, madame. 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, handle details to help the gennou index automatically in their 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.

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. My gennou are tools that please 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 hammer ever could.

For years I have encouraged people to ask themselves three questions on the subject of hammers. So I pose them to you now, Gentle Reader.

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 become an heirloom appreciated by your descendants, or will it end its days 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 posts.

In the next post 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.

YMHOS

If you have questions or would like to learn more about our tools, please use the questions 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 or incompetent facebook and so won’t sell, “share,” or profitably “misplace” your information.

Previous Posts in The Japanese Gennou & Handle Series

Part 1 – Introduction

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 posts about the Japanese gennou hammer (pronounced “gen-noh) in general and and how to design and make a unique one that perfectly fits your body and style of work.

The objective of these posts is to share with you, Gentle Reader, what I have learned over the years about gennou handles to help you design and make your own handle.

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 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, such as handles and plane bodies, 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 poorest live better than most humans did 100 years ago, partly due to widespread industrialization of all aspects of our societies 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 craftsmen purchasing pre-manufactured many things they would have made for themselves as a matter of course, including tool handles. I would wager that most woodworkers younger than 60 years old have never made an axe handle, hammer handle, or a plane body, and don’t even know how to.

Accustomed to the easy availability of standard tools, lacking an eye for performance and focused like a laser on lowest cost, most woodworkers nowadays get by with poor quality tools made by farmers in Chinese factories from poor quality scrap metal designed by kids using computers working in marketing departments that have never used a handtool professionally. Those tools may look great on the internet or wrapped in theft-proof plastic 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.

You 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 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 will be a series of performance tests listed in the last post in this series 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 and axe 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 out the door at the right price-point while fending off the hordes of snaggle-tooth slavering 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 content of our wallets and our willingness to open 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 over steel or 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 colorful, look exciting when new, 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 sell better and are more profitable than 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, than 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 rocks. I suspect humans made the first multi-component tools by attaching wooden handles to stones to make hammers, axes and clubs. 

People have all but forgotten how to make a proper tool handle nowadays, but 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 and curvier 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 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 intended to increase sales of cheaply mass-produced tools of apparently innovative design, but of mediocre quality and disposable utility. They simply look mahvelous, absolutely mahvelous dahling, especially as an illustration in a catalogue or hanging on a peg in a hardware store.

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

In the next post we will look at the history and types of gennou hammers. In the meantime, here is some music from Fernando.

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.

If you have questions or would like to learn more about our tools, please use the questions 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 or incompetent facebook and so won’t sell, share, or profitably “misplace” your information. I swear it on a stack of bibles.

Subsequent Posts in The Japanese Gennou & Handle Series

Part 2 – Ergonomics

Hammers to Use With Chisels Part 6 – Hammers & Health

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

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 hammers and chisel as a dance team effectively. In this final post we will look at how the hammers can impact our health.

Health Matters

This image has an empty alt attribute; its file name is af71ca_8a6942899be847ba9fba7a468c6c1da6~mv2.webp

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. Chopping dovetails with a pneumatic chisel is not an option, however.

When I 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, although it is no longer smooth and shiny, and I have replaced the wooden handle 3 or 4 times.

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, at 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:

  1. “Fast” and “productive” are not the same thing (the tortoise and the hare principle, “Festina lente“);
  2. 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 to remember. 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 was not suited to. 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 said things like “bring us 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 might have been right.

So in memory of those cranky carpenters who are sorting boards in the big lumberyard in the sky nowadays, 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 they 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 and curses and boots while chewing on stogies and chortling as they watched me struggle with concrete form-work 16 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.

Series Summary

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

  1. Use a steel hammer to strike Japanese chisels instead of a mallet made of wood, rawhide, rubber, plastic or brass;
  2. Use a hammer with a flat, polished face to strike your C&S Tool’s chisels for greater efficiency and to increased lifespan;
  3. 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;
  4. 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;
  5. Less swingin more cuttin;
  6. Cut the wood with a sharp blade instead of beating it to slivers and prying it out with a sharpened screwdriver;
  7. Control your chisel’s depth of cut to prevent the cutting edge from binding in the wood, slowing the work down, and dulling the chisel;
  8. Do the “chisel cha-cha” but never the “chisel wiggle;” just don’t.
  9. Don’t use the chisel to lever out waste, but instead flick waste out of joints with a quick twist of your wrist without slowing down or setting aside chisel or hammer;
  10. Work to a rhythm to maintain your cutting pace and focus.

YMHOS

Other Posts in this Series “Hammers to Use With Our Chisels”

Part 1 – Hammer Varieties

Part 2 – Hammer Faces

Part 3 – Hammer Weight

Part 4 – The Chisel Cha-Cha

Part 5 – Rhythm & Song

Part 6 – Hammers & Health

If you have questions or would like to learn more about our tools, please use the questions 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 or incompetent facebook and so won’t sell, share, or profitably “misplace” your information. May the fleas of a thousand camels infest my crotch if I lie.