The Varieties of Japanese Chisels Part 13 – The Shinogi Usunomi 鎬薄鑿 Paring Chisel

“All times are good for those who know how to work and have the tools to do so.”

Carlos Slim

The shinogi usunomi is another variety of paring chisel in the tsukinomi family.

Kiyotada Shinogi usunomi

We examined the word ” shinogi” in a previous post. https://covingtonandsons.com/2019/06/01/the-varieties-of-japanese-chisels-part-3-the-shinogi-oiirenomi/

It means ”ridge” as in the ridge of a mountain, or a building’s roof, or the back of some Japanese swords. Shinogi-style chisels have two wide bevels on their face that meet at the bkade’s centerline creating a ridge. Sometimes there is a narrow flat at the top of the ridge, depending on the blacksmith’s style and customer request.

If the atsunomi is the draught horse, the oiirenomis are the quarter horse, and the usunomi is the falcon of the chisel world ( the one in my slightly addled head, that is), then the shinogi usunomi is a Goshawk, severe in appearance, fierce, strong, fast, and skilled at maneuvering nimbly in tight situations.

Shinogi usunomi have these same two bevels and center ridge as the shinogi oiirenomi. The side edges tend to be thinner than standard usunomi, and with less material in the way, they are often just the ticket for paring into right corners. And because the ridge is higher than the standard usunomi is thick, they tend to be a bit more rigid.

And of course, since it is an usunomi (meaning “thin chisel”) it has a relatively longer and more slender neck and handle, and no crown.

A pox on anyone that would strike one of these beauties with a mallet or hammer.

One downside to this design is that the ridge down the face, which increases the overall thickness of this chisel, may make it difficult to pare down into skinny mortises. Another potential downside, but not one that bothers me, is that the ridge is not as comfortable to press on with your fingers when paring. I find this ridge gives my fingers a better sense of the blade’s precise location in my hand and in the cut. This is all personal preference that can only be evaluated through experience using both varieties of usunomi.

You may be able to tell from my choice of words that I am fond of shinogi usunomi. Indeed, I admit to prefering them. I like how they look. I like how they feel. I like sharpening them. I like how they cut. I like how the extra clearance on the side lets me see what I am paring. Subjective? Of course. And I admit they can’t do all jobs. The standard usunomi is probably a better general-use paring chisel.

The shinogi usunomi is a serious tool for serious work that looks good while doing it.

YMHOS

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YMHOS

© 2019 Stanley Covington All Rights Reserved

Please share your insights and comments with everyone in the comments section below. If you have questions or would like to learn more about our tools, please use the question form located immediately below.

Sharpening Part 7 – The Alchemy of Hard Steel 鋼

An Alchemist and his assistants working late at night in his workshop.

Behold, I have created the smith that bloweth the coals in the fire, and that bringeth forth an instrument for his work.

Isaiah 54:16 KJV

The blades we are considering in this post are made from iron and steel, so it makes sense to examine these materials from the viewpoints of sharpness and sharpening. In the previous post we looked at some of the supernatural aspects of making and forging steel. In this post we will examine some alchemical aspects.

This post could be very technical, but I have simplified the description of chemical processes to make it easier for the non-technical Gentle Reader to follow. Please bear with me.

The Alchemy of Mutating Iron to Steel

At the heart of steel alchemy is the hardening process. When carbon is combined with iron in the right proportion, steel is formed. This mutation is easily accomplished nowadays, but for most of human history it was a fiendishly difficult, expensive process. No wonder those who could accomplish the deed were attributed with magical powers.

If steel is heated to within a specific range of temperatures (difficult to measure by eye) and then suddenly cooled, crystalline structures containing small, very hard and relatively brittle crystals called carbides form within a softer matrix of iron. These hard carbides are what do the serious job of cutting, not the softer matrix. At the extreme cutting edge, this structure might be compared to a modern circular saw blade comprised of a relatively soft body to which is attached very hard tungsten carbide cutting tips.

A steel blade dulls when these carbide crystals either shatter, or the pressure and friction of cutting wears away or cracks the softer supporting matrix, allowing the carbides to be torn from the matrix leaving behind gaps of soft, blunt metal. The larger the carbide clumps are and the further the distance between them, the more easily they are shattered and torn away, and the duller a blade becomes with each crystal’s failure.

In a low-quality blade, and given the same number of carbide crystals in a fixed volume of steel, the crystals will form into relatively large and isolated clumps separated by wide rivers and lakes of softer metal, as seen from the viewpoint of a carbide. The steel will crack along these weaker pathways when stressed, and when cutting, the softer material in these lakes and rivers will erode first, leaving the carbide clumps unsupported and vulnerable to failure.

In a high-quality steel blade, by comparison, and given the same number of carbide crystals in a fixed volume of steel, the crystalline clumps are comparatively smaller and distributed more evenly throughout the matrix making it more resistant to erosion, and the carbide crystals more resistant to damage. Such steel is called “fine grained,” and has been highly prized since ancient times for its relative toughness and ability to become very sharp and stay sharp for a long time. This is the steel preferred by woodworking professionals in Japan and is the only kind found in our tools. Without exception.

Impurities and Alloys

All iron ores naturally contain harmful impurities such as phosphorus, sulfur, silicon, and manganese to one degree or another. When these impurities exceed acceptable limits, they can weaken the steel, make it brittle, or make heat treatment results inconsistent. They are often expensive to remove.

There are three approaches commonly used to minimize the negative effects of these difficult-to-remove impurities. The first is simple avoidance of the problem by employing iron ore and scrap metal free of excess amounts of these contaminants. Such ore and scrap are available, but they are not found everywhere and are relatively expensive. For centuries, the purest iron ore has been mined in Sweden.

The second approach is to add purer iron or carefully sorted and tested scrap steel to the pot thereby reducing the percentages of the harmful contaminants. This is called “ solution by dilution.”

Nakaya Takijiro’s saw forge, originally made for forging swords

The third and more common fix is to add chemicals such as chrome, molybdenum, nickel, tungsten, vanadium and even lead to the pot forming steel “alloys.” In their simplest formulations, these chemicals help overcome the detrimental effects of natural impurities, specifically those related to brittleness and unpredictable heat treatment results. Some formulations make the steel less likely to warp and crack despite impurities. Others make the steel more resistant to abrasion and corrosion, or even easier to cast, drop-forge, or machine. 

Steel alloys have serious advantages over plain high-carbon steel in mass-production, reducing material costs by improving the performance of cheaper lower-grade iron ore and scrap metal, improving manufacture characteristics, and achieving higher productivity with fewer rejects even when worked by low-skill workers.

But these alloys are not all fuzzy blue bunnies and fairy farts because edged tools made from high-alloy steels typically have some disadvantages too: Due to their crystalline structure, they simply cannot be made as sharp as plain high-carbon steel, and are more difficult and time-consuming to sharpen by hand.

Of course, additives like chrome, nickel, moly and especially tungsten are costly.

Some manufacturers cite the higher costs of high-alloy steels to justify higher prices for their products. However, what they never say out-loud is that labor costs are much much less when using high-alloy steel because skilled workers are not necessary. And because high-alloy steels produce fewer rejects, quality control is easier, overall productivity is higher, warranty problems are fewer, and profitability is increased. Indeed, without high-alloy steels, factories would need to train and hire actual skilled workers and professionals instead of uneducated seasonal workers destroying the world’s current mass-production model. Egads! Walmart’s shelves would be bare!

My blacksmiths make only professional-grade tools for craftsmen that value ease of sharpening and cutting performance above corporate profits. They charge more for plain high-carbon steel blades than for high-alloy steel products because labor and reject costs are higher. So if a manufacturer brags about the excellence of the high-alloy steels they are using rest assured increased profits are their motivation, not improved cutting performance. Caveat emptor baby.

Blacksmith

Japanese Steels

The best plane and chisel blades are made from plain, high-purity, high-carbon steel. In Japan, the very best such steel is made by Hitachi Metals mostly using Swedish pig iron and carefully tested industrial scrap (vs used used rebar and car bumpers), and is designated Shirogami (White-label) No. 1. They also make a steel designated Shirogami No.2 containing less carbon. Another excellent steel for plane and chisel blades is designated Aogami (Blue-label) No.1 and No. 2.

Aogami, like Shirogami, is made from extremely pure iron, but a bit of chrome and molybdenum are added to make Aogami steel easier to heat treat with less warping. Aogami can be made very sharp, but it is not quite as easy or pleasant to sharpen as Shirogami. Some of the plain high-carbon Swedish steels are also excellent.

If worked expertly, either of these steels consistently produce the highest quality “fine-grained” steel blades.

Let’s compare the sharpening characteristics of these two steels. To begin with Shirogami steel is easy, indeed pleasant, to sharpen. It rides stones nicely and abrades quickly in a controlled manner.

Aogami steel, by comparison, is neither difficult nor unpleasant to sharpen, but it is different from Shirogami steel in subtle ways. It takes a few more strokes to sharpen, and feels “stickier” on the stones, but it will still produce fine-grain steel blades and performs perfectly.

Inexperienced people lacking advanced sharpening skills typically can’t tell the difference between blades made from Shirogami, Aogami or Swedish steel and steels of lesser quality. But due to the difficulty of forging and heat treating Shirogami or other plain high-carbon steels, a blacksmith that routinely uses them will simply be more skilled and have better QC procedures than those whose skills limit them to using only less-sensitive high-alloy steels.

Professional Japanese woodworkers insist on chisel blades made from Shirogami steel. Some prefer Aogami for plane blades believing the edge holds up a bit better. My plane blacksmith and carving chisel blacksmith prefer to use Aogami because it is easier to work and more productive (especially in the case of carving chisels), but for a little extra they are happy to forge blades from Shirogami or Swedish Steel.

I own and use Japanese planes made from Shirogami, Aogami, Aogami Super, Swedish steel, and a steel called “Inukubi” meaning “dog neck” which was imported to Japan from England (Andrews Steel) in the late 1800’s. Of these, Shirogami No.1 steel is my favorite. It’s a matter of personal taste.

Beware of a plane blacksmith that refuses to use plain high-carbon steel and tries to charge you more for Aogami or Aogami Super steel.

The Challenges of Working Plain High-Carbon Steel

What makes plain high-carbon steel so difficult to work, you ask? I’ve never even forged a check much less a tool blade, but I will share with you what my the blacksmiths I use and swordsmiths I know have told me in response to this question.

First, plain high-carbon steel is much more difficult to successfully heat treat because the range of allowable temperatures for forging and heat-treating is narrow. Heat it too hot and it will “burn” and be ruined. Quench it at too high or too low a temperature and it will not achieve the desired hardness. Miss the appropriate range of temperatures and the blade may even crack, ruining it. Yikes.

Second, even if the temperatures are right, plain high-carbon steel has a nasty habit of warping and cracking during heat treatment resulting in more rejects than steels with additives such as chrome and moly. Strange as it may seem, when the crystalline structures that make steel useful form during quenching, they increase in volume. This change in volume produces differential expansion causing the metal to warp. This warpage can be more or less controlled, or at least compensated for, by a skillful blacksmith, but it takes real skill, extra work, and a bit of luck. Not just any old Barney can do it consistently, so when working plain high-carbon steel, a blacksmith needs to know his stuff and pay close attention.

Other than wastage due to rejects, it doesn’t cost more to forge and heat-treat a blade of plain high-carbon steel. But it takes serious skills and dedication to quality control to make a living working it for 5+ decades.

Let me give you an example of skill and experience as it relates to warpage management of plain high-carbon steel.

rThe photo below is of a swordsmith just before he quenches a yellow-hot sword blade made of tamahagane, a traditional type of plain high-carbon steel made from iron sand, in a water trough. Notice how his smithy is: he is working in the middle of the night, the time when the best magicians and alchemists have always done the most difficult jobs because temperatures are easier to judge without unpredictable sunlight confusing things. His posture and facial expression are tense because he is about to roll the bones and either succeed in the most risky part of making a sword, or fail wasting weeks or months of work and thousands of dollars worth of materials. Notice how straight the glowing blade is.

A Japanese swordsmith with a blade poised for quenching Notice how straight the blade is. He has invested months of work into this blade to this point and a misjudgment or even bad luck in the next second can waste it all. Not a job for the inexperienced or timid.

Note that the formation of crystalline carbides in Japanese swords after heat treatment is densest nearest the hard cutting edge. The swordsmith therefore forges the blade straight before quenching it in expectation of it warping to the intended curvature when the crystalline structures at the cutting edge form, as seen in the photo below. This curvature is an intentional design feature that takes years of experience to achieve in a controlled manner.

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After quenching, the warpage is dramatic. Notice the mud applied to the blade before quenching to control the formation of crystalline structures.

If the swordsmith intended to make a straight sword blade, he would have a forged a reverse curvature into the blade to compensate for the warpage that occurs during quenching. Plane and chisel blades exhibit similar but less dramatic behavior.

「折れず、曲がらず、よく切れる」を追求し、極限まで鍛え上げられた凛とした姿に、千年を超える日本刀の歴史と、生きることのすべての力を注いだ刀鍛冶の姿が浮かび上がる。
Both sides of a similar completed sword with the warpage an intentional design feature

The thinner the piece of steel being heat-treated, the more unpredictable the warpage and more likely the blade will develop fatal cracks. Within limits simple warpage can be corrected in thin blades, but not in stiffer chisels or plane blades. In the first few seconds after quenching and/or tempering a blade, the metal is still a bit malleable and warpage can be corrected to some degree by bending and twisting the still-hot blade. An experienced blacksmith will not rely solely on corrective measures but will anticipate warpage and create a curve or twist in the opposite direction when forging to compensate in advance of quenching. This takes skill and experience, and even then, some rejects are unavoidable.

Chemical alloys like chrome, molybdenum, and tungsten greatly reduce warping and the risk of cracking.

None of this is mystical, but tools made from plain high-carbon steels such as Aogami steel and especially Shirogami steel require more skill and experience than those possessed by factory workers, much less Chinese peasants, so mass-production is nearly impossible, labor costs are higher, profit margins are smaller, and advertising budgets are non-existent. No wonder such tools get little attention from the corporate shills in the woodworking press.

While modern chemistry has unveiled the mystery of steel, it has only been during the last 60 or 70 years that metallurgical techniques have been developed making it possible to understand and control steel manufacturing.

The manufacture and working of steel are still magical processes that are the foundation of modern civilization. Make no mistake: without steel and the skill to work it, human life on this planet would be short and brutal.

If you have good sharpening skills but haven’t yet tried chisel or plane blades made from Shirogami, Aogami or Asaab K-120 Swedish steel, you’re missing a treat.

YMHOS

© 2019 Stanley Covington, all rights reserved

Please share your insights and comments with everyone in the comments section below. If you have questions or would like to learn more about our tools, please use the question form located immediately below.

Sharpening Part 6 – The Mystery of Steel

“The most beautiful experience we can have is the mysterious. It is the fundamental emotion that stands at the cradle of true art and true science.” 

Albert Einstein, The World as I See It

The blades we are considering in this series of posts about sharpening are made from iron and steel, so it makes sense to examine these materials from the viewpoints of sharpness and sharpening. Let’s look at some of the supernatural and legendary aspects of working steel first.

Steel Magic

Steel is a magical substance. Since ancient times, the blacksmiths that worked it were sometimes seen as gods, sometimes as wizards. Regardless of local traditions, the power blacksmiths possessed to combine and shape the elements of earth, wind, water, fire and even spirit into the tools and weapons of everyman’s trade was seen as magical.

Even the blacksmith’s forge and anvil were seen as magical in and of themselves, and rituals incorporating them were widely believed to keep evil at bay, provide good luck and blessings, and even to cure ailments.

There were several extremely famous magical blacksmiths back in the mists of time. Allow me to present two of them to you.

Vulcan the God

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Vulcan (aka Hephaestus), Roman god of fire and blacksmithing. Archaic relief from Herculaneum (National Archaeological Museum, Naples).

The bas-relief stone carving in the photo above is of Vulcan, the Roman god of fire and blacksmithing, also known as Hephaestus to the Greeks. This carving was excavated at Herculaneum, located in the shadow of Mount Vesuvius near Pompei. Herculaneum was an ancient Roman town destroyed by volcanic pyroclastic flows in 79 AD. The word “volcano” comes from the word Vulcan, so a stone carving of Vulcan retrieved from a town totally destroyed by Vulcan’s namesake is tragically ironic in the extreme.

Die Schmiede des Vulkan (The Forge of Vulcan) by Velázquez, Diego 1599–1660) Museo del Prado, Madrid, Spain.

The painting by Diego Velázquez above is from a scene in the Roman poet Ovid’s Metamorphoses where the god Apollo visits the god Vulcan in his forge to tell him that Venus, Vulcan’s wife, is being naughty with Mars, the god of war. Apollo is on the far left and can be recognized by his crown of laurel and shining aura. Vulcan stands next to Apollo with a shocked and incredulous expression on his less-than-beautiful face (nice abs, but his beard needs a lot of work). Vulcan’s assistants have stopped their work on armour (decidedly 15th century in style) astounded by both the sudden appearance of Apollo and the news he delivers.

Obviously, Venus and Vulcan were not a happy couple. Legend says that whenever Venus was unfaithful, Vulcan grew angry and beat hammer on anvil so fiercely that sparks and smoke rose up from the top of Mount Etna on the island of Sicily, under which he had built a forge, creating a volcanic eruption.

Perhaps Apollo is sharing this tidbit of news just to help out his old buddy Vulcan, or perhaps his reason for snitching is malicious. Whatever the reason, I think it’s safe to assume people loved drama in the 1600’s too. Nothing new under the sun.

My point is that Vulcan (Hephaestus) was not only worshipped in ancient Greece but had a presence in popular culture that ranged from before an Etruscan tribe drained the swamps that became Rome in the 10th century BC, to as late as the 1600’s. And I won’t even get into Trekkie lore. Now that’s an influential craftsman.

Wayland the Smith

Wayland the Smith (Vølund Smed) 1873 sculpture. Stockholm Sweden.

Wayland the Smith was another famous blacksmith, metalworker, and magician. He was said to be a Lord of the Elvish folk who learned his trade from either giants or dwarves.

While not as old as Vulcan in human history, Wayland’s legend survives throughout Europe, and the products of his forge were central to heroic traditions of many peoples and kingdoms since the days of the first Viking longboats.

He is credited in Norse, Germanic, and Anglo-saxon legends and literature with forging magical objects of great renown, including rings of power, the impenetrable coat of ring mail worn by Beowulf during his epic battle with Grendel, the magical sword named Gram that Sigurd used to slay the dragon Fafnir, and even King Arthur’s sword Excalibur. Not just scribblers, but even Alfred the Great, king of the Anglo-Saxons c.886~899 on the island that would later become England, wrote of him.

The chains on the legs of the statue above probably represent his maiming and imprisonment on an island at the pleasure of an evil Norse king upon whom he took a bizarre revenge involving unconventional drinking bowls and jewelry. Is Wayland’s slavery one of the reasons blacksmiths have wrapped chains around their anvils since ancient times, or is the purpose just to secure the anvil and mute the bright ringing sound they make? Another mystery…

Wayland’s influence in modern times is not insignificant. For example, Leonardo Da Vinci’s fascination with flying machines was probably stimulated by the legends of Wayland building and using a winged contraption to escape slavery. And unlike Daedalu’s deadly device in Greek legend, Wayland’s didn’t melt.

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Daedalus (the bald guy) and his son Icarus (the falling guy) using wings to escape the island of Crete, home of labyrinths and monsters. Against his father’s advice, Icarus flew too near the son melting the wax securing the feathers that made the wings function. Oops.

The legends of Wayland the Smith were once deadly serious matters.

In a lighter vein, the writings of J.R.R. Tolkein, the author of the most popular works of written fiction in human history (no kidding), were influenced by these legends.

The Blacksmith’s Shop

While some blacksmithing traditions such as those involving Vulcan and Wayland are decidedly pagan in origin, others fit well with Christianity. For example, the ring of the blacksmith’s hammer on his anvil was once believed to strengthen the chains that bind the devil in hell barring him and his demons from God-fearing folk’s hearths. In darker times in human history the blacksmith’s workshop was believed by many to be a safe haven from evil forces, one that Satan and his imps actively avoided.

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The village smithy. Notice the horseshoe on the wall in the background, and its downward orientation. Due to the lack of char marks on the wall, we can tell this is not where the smith normally hangs horseshoes to cool. There is method to the madness.

Here is a link to a charming story about why blacksmiths ring their anvils and how to make sure a horseshoe brings you luck at work and at home. I encourage you to read it. Legend of the Ringing Anvil

The Japanese Smithy

If you have ever spent time in small one-man traditional smithies of the sort where our blacksmiths labor to produce the tools we carry then you know the other-worldly atmosphere typical of such workplaces. Imagine walls and exposed wooden roof beams blackened with 70+ decades of soot, the compacted but lumpy dirt floor, the darkness of carefully-managed sunlight (the better to judge metal temperatures by eye), the bitter smells of charcoal fumes, straw ash, flux, hot steel and burning oil; the roar of forced gas forges; the sounds of grinders and the antique leather belt systems that drive them; and finally the terrible racket and vibration of spring hammers and ringing anvils. A man that could work alone in a place like that 12 hours a day for 70 years is not afraid of your run-of-the-mill demon.

It’s quite a sight to see a craftsman working in such an environment. They often start late in the morning to avoid noise complaints from the neighbors, and work until late at night doing heat treating when sunlight won’t interfere with the colors of the hot metal.

By noon their arms are black to the elbows and charcoal smudges are on their faces. The sight of a small, wizened 82 year-old man with strong sinewy arms staring into yellow-hot steel as he hammers the hell out of it is a truly medieval scene. Something of the ancient magic of Vulcan and Wayland can be felt in such places.

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Mr. Junichi Takagi, Japan’s last adze blacksmith, passed away April 2, 2019. A kind man, talented blacksmith and excellent sharpener. He will be missed especially since he had no apprentices and no one will carry on his work.
Mr. Takagi working on his wet grinder in August 2018.

In the next post we will examine some alchemical aspects of the Mystery of Steel.

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YMHOS

© 2019 Stanley Covington All Rights Reserved

Please share your insights and comments with everyone in the comments section below. If you have questions or would like to learn more about our tools, please use the question form located immediately below.

Sharpening Part 5 – The Sharp Edge

The gem cannot be polished without friction, nor man perfected without trials.” 

Confucius

This post may not be as entertaining as my previous ones on the subject of sharpening Japanese woodworking tool blades: No swords or artwork or handsome Hollywood philosophers, I’m sorry to say. But with this post we will roll up our sleeves and dig into unartistic nitty gritty. I pray tender sensibilities are not offended. Many of my Gentle Readers already know most of what I will present in this post, but it is my fervent hope that one or two useful gems are hidden among the gritty.

You know the difference between the quality of work a sharp edge performs compared to that of a dull edge. Cuts are clean and finished surfaces are smooth, maybe even shimmering. Your tools are happy, singing and chirping as they cut away. But have you given thought to what a sharp edge really is?

Since the purpose of sharpening is to produce this condition in a blade, a clear understanding is useful. We will consider the basics in this post.

We shall also examine the naughty cutting edge that seems sharp but suddenly and unexpectedly dulls after just a little use. Would it be useful to know how to detect such a cutting edge before it fails wasting your time and money?

Let’s begin with bedrock basics.

The Basics

A cutting tool is essentially a wedge, with two flat sides meeting at an angle. Applying force causes it to sever materials, be it wood, metal, meat or mushrooms.

The geometry of this wedge is critical to its performance. At one extreme, the angle could be 90°. It won’t be sharp, it will be hard to push, and it will crush and tear wood instead of cutting it cleanly, but it will be durable.

At the other extreme, the wedge might be made more acute, say 3°. It could be extremely sharp indeed, but it would be too fragile to cut anything but whip cream for long. The point is that the sharp edge is a compromise, acute enough to cut well, but not so acute that cutting pressure and friction will make it dent, roll, wear away, crack or chip easily.

The effective blade must have a bevel angle that cuts the intended material well for a relatively long time. The words “well” and “long” in the previous sentence are where the magic lies. We will examine these important points in future posts in this series.

Germ’s Eye View

The extreme edge of the ideal metal tool’s extreme cutting should be perfectly smooth and only a single molecule thick. In the real world, cutting edges are rougher and wider, but still manage to cut pretty well.

Examine a sharp cutting edge under a microscope, and you will see imperfections. A dull blade will look even worse of course, showing dents, rips, and even cracks. 

knife edge_microscope800
The edge created by an 800 grit stone
Still sharp but starting to wear
A dulled and dented knife blade

Using a blade wears away and damages the cutting edge rounding and flattening it, destroying the geometry that makes it an effective wedge. Sharpening is the process of (1) restoring the intended wedge geometry; and (2) removing defects from the meeting of the wedge’s sides by abrading metal from one or both sides down past any damage, leaving a relatively clean, uniform wedge with minimal defects. This is the sharp edge. It is what the wood experiences. It requires effort to achieve, but it ain’t rocket surgery.

The most difficult part of achieving the two objectives listed above is making nothing from something, in a place that cannot be seen. Now that’s a Zen koan.

Building confidence in one’s ability to achieve results at the microscopic level is not easy. The key is to understand the goal, and to consistently follow reliable procedures. I will describe those goals and procedures in future posts in this series.

Edge Failure

The ideal cutting edge is uniformly sharp, but few edges in the real world meet these severe criteria at the microscopic level where it matters most. A blade may be sharp in some places, and dull in others. Likewise, a blade may cut well for a while and then dull quickly and suddenly. We have all experienced these irritating failures.

One common cause of these inconsistencies and failures is that the edge is sharp only because it has a defect called a burr. Burrs by themselves can be sharp indeed, but they are fragile and can bend, roll over, or break off at the root suddenly and unpredictably creating a nasty dull edge in an instant. A truly sharp edge will not just feel sharp, but will stay sharp for a relatively long time because it is properly shaped and well supported, instead of being only temporarily sharp because of an irregular and fragile burr.

I call burrs a “defect” because they are, but creating a burr is an important step in making a sharp edge. The trick is to continue to refine the wedge after the burr is created until it is gone and the edge is as perfect as we can reasonably expect to make it. Stop the refinement work too soon, or fail to do it completely, and all or part of that unreliable burr may survive to cause trouble.

So how does one tell if an edge is properly sharp and free of deceptive burrs without using a scanning electron microscope?

Do you remember ‘Nando’s philosophy described in my previous post? One must use reverse logic from our latin lover. Don’t rely on mahvelous appearance. Don’t rely on bar room tricks like shaving arm hair or cutting strips of paper. Develop skills and train your senses other than eyesight to detect the shape of steel at the microscopic level. This may sound strange but it is possible because your nerve endings are microscopic and can sense the difference between a burr and a truly sharp edge.

I will save the explanation of detailed techniques for a future post, but for now, here are two essential skills: Use your fingerprints to detect the presence and size of burrs. Use you fingernails to check the condition of the burr and determine when the blade is ready to move onto the next stone in the sharpening process. Please don’t cut yourself.

In the meantime, let’s have some pleasure before pain. Prepare to be amazed, Ladies and Germs, because in Part 6, coming soon, The Mystery of Steel will unfold before your very eyes! There will be marble relief carvings, bronze statues, oil paintings, gods and demons, death and destruction, and even a pagan soap opera about forbidden love. Oh my! We’re in negotiations for the movie rights now ♫꒰・‿・๑꒱ and need someone to play Vulcan. If anyone knows Spiderman’s agent, please have his people contact my people right away.

YMHOS

Please share your insights and comments with everyone in the comments section below. If you have questions or would like to learn more about our tools, please use the question form located immediately below.

A Cool Coat

A few weeks ago I posted an article about seismic dampers used on a high-rise building currently under construction near my office in Marunouchi Tokyo (a 3 minute walk from Tokyo Station). I pass this same jobsite on foot several times a week and take the occasional snapshot. I have other construction sites ongoing, but no high-rise buildings right now, and none that non-disclosure agreements will allow me to share with you. So this is a good opportunity to introduce you to some lesser-known details about major construction work in Tokyo as seen from the sidewalk without risk of offending any clients.

Please notice the gentleman in the orange uniform and big boots in the picture above. I have never met him before, but judging by the color of his uniform, he’s an employee with Obayashi Corporation, one of Japan’s largest and arguably most competent general contractors. I have done a lot of work with this company and respect it a great deal.

Sir Norman Foster, a famous British architect and the designer of Apple’s Campus 2 in Cupertino, California once said that Obayashi Corp is the world’s best general contractor. I tend to agree. And I say this as someone that used to work for two of Obayashi’s competitors in Japan, and who has also worked with many other contractors around the world. If you have visited the Boulder Dam near Las Vegas, Nevada recently, you probably drove over Obayashi’s bridge spanning the gorge.

Anyway, please notice that this erstwhile young man is he wearing what looks like a thick coat all puffed up like a marshmallow on a sunny day in mid-August in 37℃ (98°F) temperatures in the shade and 76% relative humidity? Is he loco, Cisco?

Setting aside the somewhat inelegant safety boots and rolled trouser cuffs which do not help the fashion statement his ensemble is making, you will notice a round white grill on his coat near his elbow. There is an identical grill on the opposite side of the coat you can’t see.

If you haven’t already guessed, the two round grills are actually battery-powered fans pulling outside air into the coat and pushing it out at his collar and wrists cooling our young contractor as he labors diligently in the heat.

Makita tool cordless fan jacket
A two-fan cool coat

These “fan coats” are very popular in Japan. They can make a big difference so long as one can perspire adequately and are credited with saving many construction workers from heat stroke and even death in hot months.

They also come in kiddie sizes and many colors.

Makita makes a “Cordless Fan Jacket” that is sold on Amazon overseas for a lot more than it costs in Japan. Instead of two fans, it has a single fan at the back. I have not used the Makita product and can’t endorse it.

The Makita Cordless Fan Jacket. Notice the high, stiff collar directing moving air over his neck for better cooling, and the fan unit at his back. The cord is leading to the angle grinder he is using, not to the fan.

I hope the weather in your neck of the woods is always balmy with cool breezes in summer so a coat like this is never useful. In the meantime, I’m just waiting for someone to develop steel-toed boots with cooling fans. (ツ)

YMHOS

Please share your insights and comments with everyone in the comments section below. If you have questions or would like to learn more about our tools, please use the question form located immediately below.

The Varieties of Japanese Chisels Part 12 – The Usunomi Paring Chisel (薄鑿)

Our thoughts flow to our hands; our tools become as part of our bodies, the blade of our bodies.

Tsunekazu Nishioka, Temple Carpenter, Horyuji Temple Restoration, Nara Japan.
Tsunekazu Nishioka

In the first post in this series, we examined the two main categories of Japanese chisels: the tatakinomi designed to be struck with hammer, and the tsukinomi used to pare wood without using a hammer. Beginning with this post we will shift our focus to several varieties of tsukinomi.

If you need to cut precise joints in wood, then you need both striking and paring chisels.

The most popular variety of tsukinomi is the mentori usunomi (面取り薄鑿)which translates to “beveled thin chisel.” The name is appropriate as the blade is long and thin and the neck gently tapered.

42mm Mentori Usunomi by Sukezane (Side View)
42mm Mentori Usunomi by Sukezane (Face View)
42mm Mentori Usunomi by Sukezane (Ura View)
42mm Mentori Usunomi by Sukezane (Face View)
24mm Mentori Usunomi by Sukezane (Face View)
24mm Mentori Usunomi by Sukezane (Face Closeup)
24mm Mentori Usunomi by Sukezane (Ura View)
24mm Mentori Usunomi by Sukezane (Ura Closeup)

Description

Just as with oiirenomi, the blades of tsukinomi can be made with different profiles, such as the rectangular cross-section of the kakuuchi, or the more triangular cross-section of the shinogi.

The usunomi has the more streamlined cross-section of the mentori oiirenomi with two bevels ground into the right and left sides of the blade’s face, flowing over the shoulders and feathering into the neck.

An atsunomi or oiirenomi can pare joints, of course, but the steel crown and mushroomed wood fibers on the handle’s end make them uncomfortable for such jobs. More importantly, the blades and handles of these chisels are often too short to provide adequate angular control. In short, the usunomi is more comfortable to use, and pares wood more powerfully and more precisely.

Western paring chisels by comparison are even thinner and have longer blades than Japanese paring chisels. There can be no denying they do a fine job. Japanese paring chisels like the usunomi have a few potential advantages worth considering, however.

The most significant advantage is that the steel cutting edges of Japanese paring chisels are much harder. The paring chisels my blacksmiths forge are around 65~66 Rc , whereas Western paring chisels are usually around 55 Rc. A Western style paring chisel with its thin blade of uniform steel hardened to 65 Rc would easily snap in half if stressed. This extra-hard steel makes possible an edge that stays sharper longer, with the result that, given the same number of sharpening opportunities and time in a given workday, a professional-grade usunomi will help you do more hours of high-quality work than a softer blade. For craftsmen that use their tools to feed their families this higher-level of performance is not something to be sniffed at.

The second advantage of the Japanese paring chisel is their hollow-ground ura which makes it easier to maintain a flat bearing surface. If you haven’t used Japanese chisels, this claim may sound unlikely. But please recall that there are narrow lands surrounding the ura, all in the same plane, that create a flat bearing surface to guide the chisel.

Usage

This tool is well-suited to reaching into narrow mortises and other wood joints to clean and pare surfaces roughed out by axe, adze, saw and tatakinomi to precise tolerances.

It excels at trimming mortise side walls and end walls. And shaving tenon cheeks and shoulders to precise dimensions without causing spelching or cutting too deeply as shoulder planes are wont to do is a piece of cake.

In addition, the longer blade and flat face of the usunomi make it ideal for paring angles, such a 45° mitres, in combination with wooden guide blocks or jigs.

The usunomi may be struck with the heel of the hand, but never with a hammer or mallet. The slender neck, thin blade, and unreinforced handle will simply not accept such abuse gracefully.

Chisels intended to be struck with a hammer typically perform best with a cutting edge bevel of 27~30°. Any shallower and the hard steel at the cutting edge may chip instantly dulling the tool. However, the cutting edges of usunomi along with other tsukinomi are not normally subjected to the high stresses chisels motivated with hammers must endure, so the cutting efficiency can be increased by lowering the angle to 24° or so without creating problems, depending of course, on the wood you need to pare and the type of paring you intend. For instance, paring end grain may require a steeper angle than long grain.

If you have used long-bladed Western chisels hard for a few years, you will have no doubt experienced your chisel’s flat becoming somewhat rounded over many sharpenings. This occurs because, for various reasons, the center portion of the blade’s flat is abraded at a slower rate when being sharpened than the blade’s perimeter, resulting in distortion regardless of whether you keep your stones perfectly flat or not.

Obviously, a chisel with a flat that is banana-shaped lengthwise and crosswise is not ideal for paring flat surfaces, but there is a bigger problem. Namely, it is simply more difficult and time-consuming  to create a sharp edge on a blade with a curved flat than one with a true flat. A flat like this begs for amateurish tricks using rulers, etc.. of the sort professionals would be embarrassed to use. A friend once scathingly described these techniques as “training wheels.” Oh my.

The ura on the Japanese chisel is specifically designed to deal with this shortcoming, and it does a great job of it.

30mm Unsunomi by Nagamitsu – View ofFace
30mm Unsunomi by Nagamitsu – View of Mitsuura

The 30mm usunomi in the photo above has an ura with three hollow-ground areas instead of one. This detail is called a ” mitsuura” ミツ浦 meaning ”triple ura.” It has the advantage of providing a larger bearing surface than the standard ura does, one that is helpful when using wooden jigs for paring to precise angles, for instance. It also helps the ura index better when paring large surfaces, especially with chisel blades wider than 24mm.

Some people prefer chisels with the mitsuura detail for their appearance. I admit mitsuura look sexy, but I am not a fan of using this detail unless it is truly necessary because of the downsides I will not deal with in this already overlong post.

If I can liken the atsunomi to a shire horse, then the usunomi is a falcon. Both are beautiful powerful animals, but just as one wouldn’t use a draught horse to chase down a rabbit, or a peregrin to pull a plow, neither oiirenomi nor atsunomi are as effective as the usunomi for paring and cleaning joints.

The usunomi is one of those tools that is a pleasure to use.

Among woodworking tools, the usunomi is special: as it becomes part of your hand, you will discover that neither the blade nor your hand but your mind is shaping the wood.

YMHOS

© 2019 Stanley Covington All Rights Reserved

Please share your insights and comments with everyone in the comments section below. If you have questions or would like to learn more about our tools, please use the question form located immediately below.

The Carpenter and the Angel

For a change of pace, I would like to share this charming folktale from Kagoshima Prefecture, Japan, of a sort traditionally told to small children.

I have included photo extracts from the Kasuga Gongen Genki E (春日権現験記絵) scrolls painted in 1309 on silk using silver and gold paints, showing carpenters working on the Kasuga Temple jobsite.

My children and I enjoyed this story. Perhaps you and yours will too.

The Tale of Tengo and Tenjin

Long long ago and far far away, there was a very good carpenter. But he was sad because he lived alone.

So he went to the prettiest girl in the village and asked her to be his bride.

She did not want to marry, but to put him off without hurting his feelings, she decided to charge him with an impossible task. 

“If you will build me a big house, with 60 tatami mats, in a single day, then I will marry you.” (60 tatami mats = approx 99 square meters = 1065 sqft based on the standard modern tatami mat) 

The carpenter was shocked by this demand, but because he wanted her for his bride, he boldly accepted the challenge saying: “I will build you this house in one day.” 

His voice rang with confidence, but he despaired in his heart knowing he could not build such a large and beautiful house in one day. He fretted to himself  “ what shall I do, what shall I do?”

But never fear, Gentle Reader, because as you have probably guessed, our carpenter was no ordinary fellow to give up easily, and before long he came up with a daring plan.

He made 2,000 dolls out of straw and breathed on each one while casting a magical spell transforming them all into human carpenters. 

The carpenter planned the building, and he and his 2,000 man crew went to work.

A cross-section of the Carpenter’s plan (dimensions are in Sun (pronounced soon) and meters). Notice the coved & coffered ceiling in the family room on the right. The essence of traditional Japanese structural engineering in wood can also be seen in this cross-section drawing: All structural members are subject to compression, or bending moments, but no tension. No trusses.
Images from the “Kasuga Gongen Genki E,” completed in 1309
The Master Carpenter and his helper use a water trough as a water level for layout. He uses a vertical string of a fixed length with a plumb bob attached to check the high stringline’s height above the water’s surface to adjust the line to be approximately level.
A crew of 3 carpenters excavate a hole and compact the soil at the intersection of two low stringlines installed by the Master Carpenter in preparation for placing a natural foundation stone, probably intended to support a main column
Carpenters use spear planes to flatten and smooth boards and a round column. Notice the wood shavings curling from the curved blades, some on the push stroke and others on the pull stroke. Spear planes were used in Japan long before blade-in-block planes became common. The guy working on the board’s right hand end appears to have his left thumb stuck in his left eye. I hate it when that happens!
The carpenters in the upper right use chisels and wedges to split timbers, while the other workers to the left use adzes to dimension and clean split boards. One appears to be of African persuasion.
The carpenter and his young helper in the drawing’s upper half use a sumitsubo (inkpot) to snap a straight line on a timber in preparation for splitting it into boards. The carpenter at the lower right closes his left eye and focuses on his sumitsubo line, which he is using as a plumbline, to orient his steel square to vertical against the log’s end. At the same time, His buddy on the opposite end is using his bamboo pen and steel square to mark a similar vertical line on the log’s end. He wet the end of his bamboo pen with ink from the reservoir of his classic split-tail sumitsub0 laying on the ground near his foot. Notice how an adze is used to keep the log in-place.
Carpenters erecting the building’s structure. No ginpoles, shoes, or tie-offs are in sight. Probably no hardhats either. And the scaffolding looks hinky. Tisk, tisk! What would OSHA say?
A diagonal view of the Coved & Coffered ceiling installed at the family room
A corner view of the family room’s coved & coffered ceiling. Notice the coped joints. This work is typically performed by joiners, not carpenters.
Related image
The living room has an even more elegant coved & coffered ceiling in plane-finished raw Hinoki wood
The living room’s coved & coffered ceiling in Hinoki wood with a carved “rainbow beam” in the foreground. Nice work!

With the assistance of his 2,000 helpers, the carpenter completed building his bride-to-be’s house before the sun went down that day,

Overjoyed, the carpenter flew to the pretty girl’s house to tell her of his success. “I have finished the house you asked for. Please marry me now!”

“Truly?” she asked. She went to see and found a big, beautiful house with 60 tatami mats, just as she had conditioned. “I will marry you.” she said. 

And thus the prettiest girl in the village became the carpenter’s bride.

The carpenter and his bride then moved into their happy new home.

Afterwards, the 2,000 carpenters scattered throughout Japan and for many years taught others how to build houses, temples, bridges and many beautiful things of wood.

After several happy years had passed, the bride said to her husband “I have been silent up to now, but the time has come to tell you the whole truth. I am not really a human being. I am an angel named Tenjin. I came down to earth from the kingdom of heaven. But the time has now come for me to return to heaven.”

The carpenter replied: “Ah, well, now that you mention it, I am not a human being either. I’m a carpenter god named Tengo. Let’s both return to heaven together.”

So Tengo and Tenjin rose high into heaven where they still live together happily ever after.

The End

YMHOS

© 2019 Stanley Covington All Rights Reserved

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Sharpening Part 4 – ‘Nando and the Sword Sharpener

And this is from my heart
Which is deep inside my body:
It’s better to look good
Than to feel good

Fernando

This post is a little longer and more roundabout than my previous posts, but I wanted to share with you some of Japan’s history, and examples of this country’s most fabulous art as produced by its blacksmiths and professional sharpeners. But before I get into that, I would like to share some relevant words of wisdom from Hollywood’s wisest man.

Billy Crystal in Fernando’s Hideaway

The handsome gentleman in the picture is Fernando. He is neither a blacksmith nor a sharpener of tools or weapons, but his insight into physical beauty and words of wisdom about happiness are pertinant to sharpening, as we shall see below. If you are not familiar with ‘Nando, I suggest you google him or view a video or two on Youtube.

So what does our dapper Latin Lover have to do with sharpening? And swords?

As ‘Nando taught the world, a wise person will not equate looking good with feeling good. Likewise, you would be wise to not confuse a blade’s appearance with its performance. Indeed, a blade that looks as sharp as the skinny end of nothing may not actually cut very well in some applications.  A good example is Japanese swords. Let me tell you a true story to illustrate my point.

When I was a University student in Japan, I was privileged to be entrusted with a number of swords that belonged at the time to the late Dr. Walter Compton, Chairman of Miles Laboratories and the inventor of Alka-Seltzer. He was a wealthy man who had a huge collection of swords obtained while an officer for the US military in Japan immediately after the war when Allied forces required the defeated Japanese people, on pain of death, to surrender all swords, civilian and military. Of course, many valuable and rare family heirlooms were surrendered or forcefully confiscated. Supposedly they all went to the bottom of Tokyo Bay in bunches, or were melted for scrap. But we know better, don’t we.

Towards the end of his life, Dr.Compton put a lot of money into having his better swords professionally sharpened, new shirasaya scabbards and furniture made, and formally evaluated in preparation for donating them to the Boston Museum of Art, where many of them reside today. Sadly, some were auctioned off without his permission. “The feckless sons of wealthy men” is the operative phrase in this case, I fear.

I assisted Dr. Compton’s representative by transporting over 70 of these swords to and from Japan and performing the necessary legwork to accomplish these goals inside Japan. During those years I held in my hands and feasted my eyes on rare and beautiful blades of great historical value several of which would have easily been designated National Treasures if they had been intended to remain in Japan (“National Treasures” may not leave Japan). 

During those years I spent a lot of time meeting, questioning, and requesting services of the best sword sharpeners in Japan, and learned a lot about swords, stones, and sharpening. Dr. Compton’s reputation was such, and his swords were of such rarity and high quality that I had no difficulty persuading the very best craftsmen to work on them or speak with me including Mr. Okisato Fujishiro.

Interestingly, in Japan such craftsmen are called “Togishi” (研師), an unambiguous word that can only be translated as “sharpener.” However, in the West these same Japanese craftsmen are called “ Sword Polishers.” In the post-war context, this actually may be more accurate than the Japanese term.

A very subtle, high quality sword tip brought to life by the arts of the Sword Sharpener. Notice the peaceful elegant hamon (wavy milky pattern at the cutting edge oriented towards the top of the photograph), the grain of the steel just below the hamon, and the burnished polish surrounding the fuller. Notice also the clean delineation where the blade tip, the “boshi,” begins. Very nice work.

Traditional Japanese society before the elimination of the caste system had 4 main divisions labeled  “Shi No Ko Sho,” meaning, in descending order, Warrior (samurai) Farmer, Craftsman, and Merchant at the bottom. The Emperor, Court Nobles, and Shoguns were above these strata, although only the Shogun possessed any actual power of the three. The man with the sword makes the rules, and those without weapons do what they are told or die. Such it has always been.

Blacksmiths and sword sharpeners were both in the craftsman caste, but the sword sharpener was above the swordsmith in rank. Depending on their support among the warrior caste, and with the generous application of yellow metallic lubricant, both swordsmiths and sword sharpeners occasionally obtained noble rank, an honor to which most other craftsmen, farmers, and merchants could not aspire My point is that sword sharpeners, while of low caste, often had a perceived rank higher than their craftsman position would suggest.

Why was the Japanese sword sharpener of higher rank than the swordsmith? I haven’t seen documentation from back in the day confirming it, but I suspect it is because the sharpener turns the swordsmith’s plain steel blade into a thing of jewel-like sculptural beauty that almost seems alive. One only has to see a sword blade fresh from the blacksmith’s shop and compare it with the same sword after the sword sharpener’s ministrations to understand.

The Nikko Sukezane sword, a designated National Treasure of Japan
Related image
This sword is known as the “Nikko Sukezane,” Nikko for the temple commemorating the Shogun Tokugawa Ieyasu (徳川家康, January 31, 1543 – June 1, 1616) where it is stored, and Sukezane (助真 meaning “Aid the Truth) for the name of the smith who forged it for the Kamakura Shogunate (1185~1333). The blade’s shape and crystalline pattern above the hamon are characteristic of Sukezane’s work. This sword’s brother was in my care for about 2 years while it was being polished and appraised in Tokyo.
大般若長光-画像2
This sword is another of Japan’s National Treasures. It was forged by a swordsmith name Nagamitsu (長光)during the same time period as the Sukezane above. The tang (nakago) is corroded by exposure to bare hands over a period of around 700 years. Multiple holes were drilled in the tang to accomodate different kinds of hilts during its lifetime. I also had a sword by this same smith and of very similar appearance in my care for about one year, although it was not owned by Dr. Compton.
A different Nagamitsu sword, also listed as a National Treasure. An unusually healthy example.

I have even witnessed a skilled sword sharpener create a beautiful hamon (a pattern formed on the edge of a sword by the steel’s crystalline structure) on a sword forged by a famous smith that had lost the crystalline structure necessary to form an actual hamon. While a deception of sorts, the intention was not to deceive for profit (the sword was donated to a museum), but to return an unusual and historically important sword to its former beautify, a glory that would have been lost but for this sword polisher’s exceptional skills.

A dramatic chouji midare hamon in a modern sword. The pattern exists because of the changing crystaline structure of the blade that results from the differential heat treatment process performed by the blacksmith, but it is only visible and beautiful because of the sword sharpener’s stones and his skill with them. Is the blade sharp? Don’t judge a blade’s performance by its polish.

If we liken the swordsmith with his forge and hammer to the quarry worker cutting marble from the mountain, then the sword sharpener is Michelangelo cutting the Pietà with his chisels and files. Both craftsmen work on the marble and blade respectively, and both are essential. The sculptor uses steel to bring stone to life, while the sword sharpener uses stone to bring steel to life.

chojimidare.jpg
Another dramatic hamon in a modern sword.

But despite these artistic abilities, modern “Sword Polishers” have no interest in and make no effort to actually make a sword blade cut well. Indeed, in some cases, they actually intentionally dull the blade so it can’t cut, thereby making it safer. This intentional vandalism is called “habiki.”

A different style of hamon pattern on a blade with a different grain pattern. Notice the different colors and lines inside the hamon. All these tiny details have names, are categorized and studied intensely by aficionados. All things equal, this sort of pattern and color is considered to be more elegant and desirable than the two more dramatic hamon pictured above. An extremely deep rabbit hole, I assure you.

Here is the key point I want you to understand: Despite the long years of apprenticeship, advanced skills learned, and gallons of blood unintentionally leaked by sword sharpeners, the frank sword sharpeners I have spoken with all admitted that, of all the craftsmen in Japan that used edged tools, woodworkers like carpenters, cabinetmakers, and joiners routinely create sharper blades despite those blades not appearing as sharp as swords. This is consistent with my direct experience of handling over 70 swords before and after being worked on by sword sharpeners.

While there is great pleasure to be found in polishing a plane or chisel or knife blade to levels of great beauty, do not make the mistake of equating appearance with performance.

Appearance aside, and looking strictly at cutting performance, will a chisel or plane or knife blade skillfully sharpened on a 15,000 grit stone cut better and longer than if sharpened on an 8,000 grit stone? In the case of woodworking blades and kitchen knives, no it won’t. In fact, due to higher levels of friction in the cut, it will certainly not cut wood as well. More on this subject later.

Hidarino Ichihiro Oiirenomi. The hazy silver of the hard steel hagane lamination and the cloudy grey of the softer iron jigane lamination, combined with the shape and upward curvature of the corners of the lamination are indicative of unexcelled craftsmanship by the blacksmith, superior skills of the sharpener, and excellent stones. Such details are considered sublimely beautiful to tool connoisseurs. But will the edge cut well? We can’t tell from this photo.

Keep in mind that the stones used to apply the beautiful polish and accentuate the hamon on Japanese swords are different from those used to sharpen woodworking tools. For instance, the uchigumori stones sword polishers use are small slices of very soft stone glued to paper using urushi lacquer, and are only 3,000~5,000 grit. These small slips of stone are rubbed on the sword blade using thumb and fingertips.

Here is a link to a blog showing Mr. Fujishiro, son of one of the sword sharpeners I employed back in the day, making and using these thin slices of stone.

Tools are designed to perform specific tasks. Although it could do the job, more or less, you wouldn’t use a crescent wrench to stir spaghetti sauce on the stovetop would you? A longish spoon just might work better. Does a sword’s edge need to be extremely sharp to cut the enemy effectively? No, it doesn’t because the sword’s speed, impact force, and swordman’s technique influence its cutting effectiveness much more than sharpness. So sword sharpeners have always been more focused on edge durability, resistance to chipping, and appearance than absolute sharpness. In modern times, when swords are almost never used to cut living flesh outside of Saudi Arabia, the blade’s appearance may be critical, but sharpness is not a practical concern.

Another example is food preparation knives. A chef’s knife looks terribly sharp, and as it slices tomatoes and fillets fish we can see that it cuts well. But how sharp is it really? In comparison with a joiner’s plane blade, not really that sharp. But both tools are exactly suited to the job assigned them.

柳刃包丁(刺身包丁)
The sashimi knife is made long to facilitate long draw-strokes that cut the fish cleanly. The chef applies little downward pressure which would rupture the cells ruining the flavor of the tuna sashimi. Yes, a properly sharpened knife and expert technique make a difference in flavor, just another reason why the Japanese are obsessed with sharp things.

The chef’s knife is most effectively used in slicing or drawing motions, much as expert swordsmen use their weapons against enemies. In this style of cut, a smooth and uniform cutting edge does not perform as well as a more ragged, serrated edge as seen at the microscopic level. Therefore, there is little if any practical benefit (assuming beauty is not practical) to be obtained by sharpening a kitchen knife beyond 1,000 or 2,000 grit. In fact, at least in Japan, these are the upper-limit of stones in daily use by professional chefs of all varieties. Yes, and that includes sushi chefs.

But don’t misunderstand my point: In the case of both swords and yanagiba hocho knives, the bevel angle must be correct for both the blade being used and the material being cut, and the microscopic edge must be a clean intersection of planes. If you get these two factors wrong, a crescent wrench might work just as well.

The other point I want to make is that, while I enjoy using high-level skills to create a very sharp blade with a beautiful appearance, such a blade will not perform better than an identical blade of equal sharpness but with a less polished appearance, and the extra time and money spent on improving outward appearance is wasted on bread and butter work. 

Since Hollywood celebrities have the answers to all the world’s problems (at the cost of other people’s money, labor and freedom, of course) perhaps our quest for the sharp edge can benefit from the wisdom of the famous Latin lover ‘Nando, Tinseltown’s most elegant star. ‘Nando once shared his father’s advice that it is “better to look good than to feel good.” Accordingly, perhaps we should all go crazy nuts and polish our blades like beautiful but dull museum swords and wear waistcoats and cravats as we cut sliding dovetails and plane door stiles. After all, one must be ready for every photo op. In this way, our woodworking blades may be worthy of ‘Nando’s highest praise: “You, dahling, you look mahvelous, absolutely mahvelous.”

Fernando Lamas in “The Merry Widow.” The crease in his pant leg could slice bacon.

No, on second thought, while there is much one can learn from Fernando’s elegant philosophy, his standards of beauty and suffering are too high for me. I would rather be a simple joiner or cabinetmaker in stained work clothes that has the ability to make a blade exceptionally beautiful but chooses not to expend the time and cost required to do so most of the time, rather than someone who doesn’t because they can’t.

Although Fernando has a pressing appointment for a tango lesson he must give (discretion prevents me from naming the young lady he is pressing) and won’t be providing further insight, our adventures in sharpening Japanese woodworking tools will continue in Part 5 of this series.

Let’s meet at Tsukiji for sushi afterwards.

YMHOS

© 2019 Stanley Covington All Rights Reserved

Please share your insights and comments with everyone in the comments section below. If you have questions or would like to learn more about our tools, please use the question form located immediately below.

Sharpening Part 3 – Philosophy

A wild boar was sharpening his tusks upon the trunk of a tree in the forest when a fox came by and asked, Why are you doing that, pray? The huntsmen are not out today and there are no other dangers at hand that I can see. True, my friend, replied the Boar, but the instant my life is in danger, I shall need to use my tusks. There will be no time to sharpen them then.”

Aesop (621~565 BC)
Always ready for battle

It’s nice to have a philosophy on a subject because it helps one distill random thoughts down to the essentials.

Allow me to explain my philosophy about sharpening woodworking tools, not because it is charming and unique, and not because you should emulate it, but because it will provide insight into the things I have written and will write about sharpening on this blog and elsewhere. Use it to calibrate your BS meter. It is often neck-deep when people talk about sharpening stuff.

My philosophy regarding sharpening was shaped by my experience as a carpenter, contractor, commercial cabinetmaker, and joiner working under pressure, against a clock, sometimes with a boss watching with eagle eye, and often in front of customers, not as a hobbyist fiddling around in a garage workshop. Married young with a growing family to support, I quickly discovered that children eat constantly and in ever-increasing quantities, so efficiency was and is important to me. 

Efficiency was also important to the Clients who hired me. Sharpening and maintaining tools was indeed part of the job, but from the Client’s viewpoint, it was wasted time, so it was important to minimize time spent fiddling with tools during the work day. I followed the example of craftsmen I respected and started the day with sharp tools in good working order, and kept spare planes and chisels sharpened and ready to go as backup.

Self-employment hammered into me the monetary value of time. It also taught me quality sharpening stones and tools are expensive and wear out, and that to feed wife and babies every day I had to work efficiently to minimize time and money expended on maintaining tools, while maximizing the amount of work I accomplished between sharpening sessions. 

I developed a strong dislike, nay hatred, for blades that fail, dull quickly, or take too much time and effort to sharpen. I loathe them not just because they are irritating, but because they waste my time and money. Even considering the higher initial cash outlay, the cost-effectiveness of handmade, professional-grade tools in helping my mind and hands feed the family became as obvious as a road flare in a candlestand.

You, Gentle Reader, may not feel the time and financial pressures that professionals do, but learning how to sharpen your tools more efficiently will make woodworking less frustrating, more profitable, and more enjoyable.

What is your philosophy?

Sharpening a chisel at the jobsite, then back to work, jiggety-jog.

The journey will continue in Part 4 with wisdom from a celebrity and pictures of pretty swords.

YMHOS

© 2019 Stanley Covington All Rights Reserved

Please share your insights and comments with everyone in the comments section below. If you have questions or would like to learn more about our tools, please use the question form located immediately below.

Sharpening Part 2 – The Journey

You don’t have a soul, Doctor. You are a soul. You have a body, temporarily.” 

Walter M. Miller Jr., A Canticle for Leibowitz
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Life is not a race. It’s a hard journey along many paths all leading to a single gateway.

What matters in this journey are the friends and family that travel with us, the kind deeds we do, the joy we share, the things we learn along the way, and the quality of our souls at the journey’s end. It’s no coincidence that these are all that will remain with us after we pass through the gateway.

Woodworking is both something we learn and a source of joy during this journey. For many it is a way to keep body and soul connected.

Travelers on the path to becoming excellent woodworkers learn early that dull tools will not and cannot make excellent wooden products regardless of the skill of the hand and eye that manipulates them.

Indeed, dull tools are not simply inefficient; I believe they are an impediment to good work because, being an extension of the user’s mind and hands, a dull tool will often darken the mind and leaden the hand of even an accomplished woodworker.

It is no coincidence that for millennia the first thing apprentices were taught once they were permitted to handle valuable tools was how to sharpen them properly. It has always been the first and most important woodworking skill.

Anyone who aspires to become an accomplished woodworker and more than an artisan or machinist must obtain minimal sharpening skills. All other woodworking accomplishments flow from this bedrock skill. This attitude has thousands of years of history behind it.

In our time the prevalence of machinery with built-in precision and blades driven by motors and sharpened by others has made it possible for those lacking even basic sharpening skills to represent themselves as craftsmen. Although they may be skilled artisans, I believe such individuals are less craftsmen and more machinery operators.

I believe, perhaps because the men I learned from and respected also believed, that free-hand sharpening is the way a skilled craftsman maintains his tools. My experience and observations over many years support the validity of this belief and the efficiency of the results. It is consistent with my work-driven philosophy about sharpening I will explain in more detail in the next post in this series.

Sharpening a blade free-hand is a zen-like activity. It requires observation. It requires muscle memory. It requires consistency. It requries composure. It requires meditative focus. And at the pinnacle, it requires one to feel with hands and hear with ears a place that cannot be seen, a place where destruction creates order. A place where nothing becomes something.

Some will disagree with my beliefs about free-hand sharpening, especially the machinist-types, those disinclined to remove their “training wheels,” the scribblers and gurus promising instant results in a few hours for the price of a book, DVD, or class, and the purveyors of sharpening jigs, of course. No mystery there.

When accomplished woodworkers gather in the presence of edged tools, they will always be curious about the quality of other men’s tools. In Japan, it is considered rude to pick up another man’s tools and examine the edges, or even to look at them too hard, but the desire is always there nonetheless because it is human nature to compare oneself to one’s peers. 

Indeed, much can be learned about a man’s quality standards and skill from his blades. Perhaps the condition of his tools can give a tiny glimpse into his character. Who can say?

What do your tools say about you? They are terrible gossips, you know. (ツ)

The journey will continue in Part 3 with wisdom from a celebrity and pictures of pretty swords.

Tianmen Gate, China. 999 steps in the stairway.

YMHOS

© 2019 Stanley Covington All Rights Reserved

Please share your insights and comments with everyone in the comments section below. If you have questions or would like to learn more about our tools, please use the questions form below.