Sharpening Part 14 – Natural Sharpening Stones

The finest, softest natural stone your humble servant routinely uses. Black Cashew natural urethane paint (made from cashew nuts) has been applied to the bottom and sides to retard water infiltration and prevent de-lamination in this sedimentary stone. It is a joy to use, and all my blades simply wiggle with joy when its their turn for a ride.

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

We receive a lot of inquiries about natural finishing stones, so your humble servant wanted to share some accumulated thoughts and experiences about them with Beloved Customer. Perhaps they will be useful.

To begin with, natural Japanese stones are a lot of fun, and can create a beautiful, cloudy finish on a blade’s bevel. They make my heart sing, wild thing.

I think blades finished with a natural stone tend to stay sharper a little longer compared to synthetic stones, but can’t prove it. Despite my fondness for them, I want to make it clear that natural stones are not magic, and are not critical to doing good work.

It is interesting to note, however, that while top-quality natural stones are expensive, if judged by the amount of steel they can sharpen, they are actually no more costly than the better synthetic stones. But they can be more of a gamble.

Geologists believe (they weren’t around at the time to witness the event, although they like to pretend they were) that Japanese natural sharpening stones were created when particles of volcanic dust fell from the sky, were sorted, and sifted by winds and waves, and settled onto the sea floor eventually becoming sedimentary stone. Sounds likely.

Being natural, they carry the inherent and potentially expensive risk of internal defects, such as weakness between sedimentation layers, cracks, and contamination such as hard particles of sand concealed inside. Even if you find one that seems perfect in every way, the bones never stop rolling because you never know what lurks inside.

This stone is a medium hardness natural finishing stone I regularly use.

The stone is epoxied to a base made of Ipe wood. The sides are coated with a natural urethane called Cashew, a product of the cashew nut tree, to prevent water from soaking into the stone’s sides potentially causing cracks and delamination. The bright orange color is to ensure pesky pixies do not talk the stone into sprouting legs and walking away when outside the workshop. They can be persuasive when talking to stones, donchano.

Your foolish servant erred with his first purchase of a natural stone, one recommended by a hardware store owner in Sendai many years ago. I fear he intentionally foisted a low-quality stone on me that a person more experienced with natural sharpening stones would have rejected. This stone “drags” steel, a phenomenon where the stone deposits hard clumps on the blade that then gouge the stone’s surface and leaves rough spots on the blade. It’s impossible, BTW, to judge a stone’s propensity for this pixieish behavior by eyeball alone.

I learned a bitter and expensive lesson about both natural stones and salesmen that day. I still use that stone for sharpening axes and gardening tools and as a door prop, but the real reason I keep it around is as a reminder of my foolishness.

After that disastrous adventure, I became more careful and paid less attention to what people said or wrote. Consequently, I don’t give a rodent’s ruddy fundament about most people’s opinions on the subject of sharpening stones. Nearly all who claim expertise talk and write about things they only partially understand. Many have a conflict of interest. Still others seek justification of their poor decisions.

Nor I do care about the region or mountain or mine a stone came from, or its designation or color. A word to the wise: Even the best mines produce mostly waste.

And because of the impossibility of evaluating stones long-distance, and considering Gildor’s wise words quoted above, I am hesitant to give advice about what stones to buy or where to buy them. But I will tell you what I do when buying a stone:

I examine the stone for cracks and signs of irregularities and impending separation at its sides (not all defects are fatal);
I flip it with my fingertips and listen to the sound it makes. Yes, a good stone sounds different from a bad stone;
I take the stone in my hand, close my eyes, and feel it with my ki 気. Does it feel sound and happy?;
I touch my fingertip to my tongue, wet the stone just a bit, and smell it;
I touch it to my teeth (an ancient technique for detecting the fineness and consistency of a stone’s abrasive qualities);
I put a plane blade I know well to the stone, take a few strokes, and like a bow on violin strings, I feel the friction and listen to the music made;
I examine the scratches the stone leaves on the blade’s jigane and hagane using a loupe.

None of these critical tests can be conducted long-distance. BTW, if you think any of them are pointless, then I know where you can get a good deal on some swamp land in North Korea with its own lake perfect for a condo development. Well, actually its a settlement pond for a chrome plating factory, but the effluent discharge was recently brought up to 1876 standards so there is no pesky vegetation, or endangered fish or wildlife to deal with, and the price is right!

I have two natural stones I use regularly nowadays. One is of medium hardness suitable for most every straight blade. The other, pictured below, is very soft, and easily damaged, but creates a beautiful foggy finish on the steel.

I love my natural finishing stones, the feel of using them, their smell, the music they make and the pretty finish they produce on my blades. They are part of the romance unique to Japanese blades. I believe the stones I use now and their sisters worn to slivers in past decades were worth every penny I paid for them, but I recognize this is an emotional rather than practical viewpoint, and difficult to defend economically.

Don’t misunderstand: your humble servant is not suggesting you should not try natural sharpening stones, only that you carefully evaluate them in-person beforehand, and buy from a reputable dealer that offers a reliable warranty (please don’t ask for recommendations). And just to prove I am neither troll nor curmudgeon, I will give you the same four points of sound advice about purchasing natural sharpening stones that a wise old man gave me a long time ago, advice that has passed Gildor’s test.

First, don’t trust your eyes alone when judging a stone’s origin, designation, appearance, or performance (see the five tests listed above);
Second, don’t buy a stone from someone you don’t trust and who won’t give you a reliable 30 day warranty. That gives you time to check the stone carefully for suitability and defects. Remember, the combination of stone and blade is much like a marriage where the softer (but actually granularly harder) stone smooths and polishes the harder blade. If the two don’t work well together, then even lawyers can’t make it right, but a warranty may help reduce the damage;
Third, always try a blade on the stone before purchasing it to make sure it works for you and your blade;
And fourth, don’t whine if the stone disappoints: roll the dice and smile at the spots they show you. Besides, hoes, axes, and hedge shears need sharpening love too.

On the other hand, if you can follow the last rule and don’t mind risking your money, then the previous 3 rules can perhaps be ignored. I grew up in Sin City and know that can be fun too. You pays your money and you takes your chances. Baby needs a new pair of shoes!

Finally, if and when you find the perfect natural sharpening stone, you should protect it from damage and ensure it serves you long and reliably. The link below is to an article on this very subject: Protecting Natural Sharpening Stones

Ancient Roman or Norse dice in a pose worthy of gambling.

YMHOS

If you have questions or would like to learn more about our tools, please click the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.

Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google, fascist facebook, or thuggish Twitter and so won’t sell, share, or profitably “misplace” your information. If I lie may I always roll snake eyes.

Links to Other Posts in the “Sharpening” Series

The Story of C&S Tools

This image has an empty alt attribute; its file name is kiyotada-24mm-atsunomi2.jpg — A Kiyotada 24mm atsunomi, the first truly professional-grade chisel I purchased over 33 years ago. It’s an elegant tool with awesome performance. I got it at a discount because of some cosmetic defects I polished out, which is why the finish is bright and the neck is slightly rusted.

“End? No, the journey doesn’t end here. Death is just another path, one that we all must take. The grey rain-curtain of this world rolls back, and all turns to silver glass, and then you see it. White shores, and beyond, a far green country under a swift sunrise.”
J.R.R. Tolkien, The Lord of the Rings”

The story of C&S Tools is not one of a business looking for products to sell, or of a manufacturer looking for buyers, but of craftsmen looking for better tools.

Your humble servant has lived and worked in Japan for many years, and learned about Japanese woodworking and Japanese tools from serious professional craftsmen called “shokunin.” They included primarily carpenters and joiners, gentlemen that were obsessed with the quality of the products they produced, their production efficiency, and the performance of their tools.

These gentlemen influenced me to seek out the best handmade woodworking tools available, including chisels, planes and saws because better tools help one perform better work more productively while making the job more pleasant. I am still absolutely convinced that is true.

I bought many different brands of tools back in the 1980’s and tested them. I asked craftsmen who’s skill and work impressed me what brands of chisels and planes and saws they used. After years of trying various brands, in the end, I concluded that Kiyotada and Ichihiro made the best chisels and Yokozaka Masato made the best plane blades available at the time. Over the next ten years, I disposed of my other chisels and planes and built up sets of chisels and planes by these blacksmiths.

My work has required me to move many times. In 2009 I was transferred back to Tokyo from Southern California, but the moving company mistakenly placed all of my chisels and planes in storage in the US instead of shipping them with me to Tokyo, so for several years I did not have access to them.

I no longer use my tools to feed the family, but still enjoy woodworking as both hobby and therapy to help maintain my sanity, so life in Tokyo without my tools was lacking something important.

I tried to purchase a few of my favorite tools by Kiyotada, Ichihiro, and Yokozaka but found they were no longer available, and because of the Kezuroukai effect, even used ones had doubled in price. Only Yokozaka-san was still alive, but once again, the Kezuroukai effect resulted in long waiting lists and inflated prices for his planes.

I eventually purchased a 10pc set of oiirenomi bench chisels from a retailer I trusted under the brandname Kiyohisa because, while the retailer warned that Kiyohisa’s products were nowhere near as good as Kiyotada or Ichihiro, he insisted that the Kiyohisa brand was as good “as it gets” anymore. They were shockingly expensive.

Sadly, I discovered the Kiyohisa chisels to be not only inferior to Kiyotada’s products, but of poor quality even when compared to cheapo tools, with some blades chipping unduly, others rolling their edges, and still others with poorly-performing differentially-hardened cutting edges. Absolutely hopeless. I was irate.

I took them back to the retailer and demanded a refund, but he responded that Kiyohisa products did not have a warranty. I since learned that this blacksmith does not warrant any of this products. As you can imagine I lost faith in that retailer’s opinion and the products they sell. You can probably imagine my opinion of Kiyohisa too, so I won’t inflict you with the rant.

At this point I was thoroughly frustrated and so procured many different famous brandname chisels and tested them to destruction. The standard against which I compared them all was the excellent Kiyotada products forged by Shimamura Kosaburo, a blacksmith who was at one time lauded by metallurgists as being the best chisel blacksmith in Japan. I have yet to find a better chisel, but I tried. The testing criteria were initial sharpness, durability (resistance to cracking and chipping) and edge retention ability.

The testing process I employed was to sharpen each 24mm chisel’s blade to 10,000 grit, and cut mortises with it in a Japanese hardwood called Keyaki (zelkova wood). I would abuse each chisel to determine how tough it was, and examine the edge after cutting each mortise. If the edge rolled or dented (and many did), then I knew it was too soft and rejected it. But if it chipped, broke, or performed well, I took it to the next step where I re-sharpened it and continued to cut mortises until the edge chipped or dulled. I rejected those chisels that readily chipped or quickly dulled. Most of the newly-produced chisels sold under famous brand names, and all the chisels produced in Miki, which were too soft, failed these comparative tests utterly.

It was an expensive process but I learned an important lesson, namely, that brandname has nothing to do with quality or performance; The true source of quality and performance in edged tools is rather the blacksmith himself, his experience, skill, and rock-solid dedication to quality. Sadly, this common-sense logic is not applicable to mass-produced products.

The key point I want Beloved Customers and Gentle Readers to take away from this story is the fact that most “brandnames” are owned by by wholesalers and retailers and are marks stamped onto products sold to faceless “markets” that have no direct voice, whereas blacksmiths sell to “customers” that give them direct feedback.

Right about now astute Beloved Customers and Gentle Readers are no doubt saying to themselves “Aha! But the wholesalers and retailers are still customers. Forsooth! Is their opinion of no worth?”

As always, our Beloved Customers have hit on an important difference to which I am compelled to provide a distinction. To whit, wholesalers and retailers are, with few exceptions, shopkeepers to whom a hard day’s work entails packaging boxes and writing labels, not producing timber frames, cabinets, or furniture. Most have never used a tool in the field or workshop professionally. Accordingly, while many talk a good game, their only source of feedback is the volume of sales and product defects complaints received from their customers. Their focus, therefore, is on moving volume at the highest possible profit margin, not making sawdust. In short, lacking hands-on experience and motivation from a demanding foreman or Clients, their ability to differentiate quality and performance from one brand to another is like the proverbial fundament and elbow.

I digress. Back to the point of the story.

Wholesalers and retailers don’t care about feedback so long as product keeps moving. If a particular brandname stops selling, they change the brandname and dress the product up in a different color miniskirt and sequined hooker heels and send it back out to the street corner, so to speak. Thus it has always been.

But the blacksmith has only his reputation, a precious thing that, once lost, cannot be recovered with a fashion remake and a new hairdo.

Accordingly, the quality and performance of a blacksmith’s products directly impact his personal reputation, self-respect, and long-term income, as illustrated by the example mentioned above, whereas most wholesalers and retailers have little at stake.

If a tool wholesaler’s primary market is amateurs located in far-flung countries outside of Japan, then the fluid reputation of his brandnames, inflated by marketing, have much greater influence on his profits than blade quality. Indeed, few amateurs in any country know how to properly use and maintain professional-grade chisels.

Even in Japan, amateurs carelessly damage blades blaming their failure on the blacksmith. Therefore, when marketing exclusively to inexperienced amateurs either domestically or internationally, the wholesaler’s surest path to profitability is to sell mass-produced blades with a high profit margin that are softer and more resistant to damage than blades intended exclusively for professional woodworkers. Therefore, blades sold primarily to amateurs overseas do not need to be hand-forged from the best materials but can be mass-produced using less-expensive steel at lower cost resulting in higher profits. And since the brandname is fluid and can be repaired through marketing, quality is of little consequence.

That is the Miki way of doing business, very much in the style of MacDonalds. Do you like kangaroo meat?

I had learned an expensive lesson during this first phase of buying chisels and planes and destroying their blades. And so putting it to good use, I next went looking for real live blacksmiths instead of famous brand-names.

I focused on traditional blacksmiths unaffiliated with the large wholesalers, working in small smithies who continued to produce chisels and planes for professionals using traditional blacksmithing techniques, and did not stoop to mass-production. I had set myself a time consuming challenge that couldn’t be accomplished using the internet or telephone alone. Indeed, these craftsmen don’t even own computers or mobile phones.

During the next phase I bought more chisels and damaged more blades. I spent weekends on trains going all over Japan visiting woodworkers and blacksmiths, inspecting forges, and checking QC techniques and steel stockpiles. At last I found 3 chisel blacksmiths and one plane blacksmith that consistently produced only the professional-grade tools I wanted with real-world performance approaching that of Kiyotada, Ichihiro, and Yokozaka.

I should add that Kiyotada, Ichihiro, and Yokozaka’s tools were expensive even when they were alive and producing daily. But since the tools I was seeking were to be secondary, perhaps temporary tools, I was willing to sacrifice appearance for lower cost on condition that the tools satisfied my performance goals. The blacksmiths I found did not make the prettiest blades, but they all cut like crazy and kept cutting a long time without dulling or chipping.

During this process I was in communication with professional woodworker friends in the US that know how to use and maintain Japanese planes and chisels. I told them of my adventures and even sent them some of the tools I found to try. After testing the tools they too wanted some. Word of mouth spread and one thing lead to another.

I have a day job, so C&S Tools is not focused on maximizing profits. We sell our tools for the standard retail price in Japan plus PayPal fees of 4.1%, without a gaijin or export markup. It’s more of an excuse for me to spend time with the Japanese blacksmiths and other honest craftsmen I respect.

Unfortunately, our blacksmiths are not getting younger. All are in their late 70’s and 80’s. Production will not continue much longer, so if you are looking for professional-grade chisels and planes at a reasonable price, as I was, then don’t wait too long. No one knows when the “grey rain-curtain of this world will roll back and all will turn to silver glass,” as the old wizard put it.

Stan Covington, Your Most Humble and Obedient Servant.

This image has an empty alt attribute; its file name is atsunomi-sukemaru-30mm-wo-shoulder.jpg — *A 24mm Sukemaru brand atsunomi*

If you have questions or would like to learn more about our tools, please click the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.

Please share your insights and comments with everyone using the form located further below labeled “Leave a Reply.” We aren’t evil Google, fascist facebook, or thuggish Twitter and so won’t sell, share, or profitably “misplace” your information. If I lie, may my chisels chip and my plane blades chatter and gossip unceasingly!

The Varieties of Japanese Chisels Part 15 – Ootsuki Nomi 大突き鑿

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

The Ootsuki nomi is the largest of the Japanese chisels. It is essentially a scaled-up tsukinomi paring chisel, equivalent to what is called a “slick” in the West.

Definitions

The name is written 大突鑿 using Chinese characters. The first character 大 means “large,” or “ big.” Besides “Oo “ this character can also be pronounced “dai.” You may notice it looks like a man with his legs spread and arms extended, as if he is describing to his buddies the size of the fish that got away. At least that’s how I remembered the meaning when I was a young man in Japan many moons ago.

The second character 突 means to “push against.” And the last character 鑿 , pronounced “nomi” means chisel. It is a very complicated character the origin of which is a mystery to me and everyone I have asked.

So the name translates directly to “large push chisel.”

Applications

If you have never done timber framing, a brief explanation may be helpful.

When doing production work (versus hobby stuff) one cuts the pieces and parts of most open joints using electrical circular saws. Chainsaws kinda work too, but with much less precision.

Handsaws are also necessary for some cuts, but for most situations a circular saw is much quicker and less tiring. There’s a lot of wood that needs cutting after all and only so many hours of sunlight in a day.

Mortises are typically cut with portable electric hollow-chisel machines. There are other options such as portable chainsaw mortisers, stationary router machines, or the amazing German Hundegger machines. http://hundeggerusa.com

I once worked for a Japanese company that cut entire wooden structural frames using CAD driven CNC machines in a factory. In that situation however, the CNC machinery, while very precise and very quick, was so expensive and so inflexible that the building had to be designed around the repertoire of joints and sizes the machinery could cut rather than the joints required to make the best building. And it could not handle significant dimensional irregularities in the timbers used, so only machined glulams were suitable. A very limiting endeavor indeed. I left that job after 2 years.

In any case, hand-operated powertools tend to be less-precise than large CNC machines, leaving rougher surfaces and tolerances that often need fine adjustment without messing around. This is where the ootsukinomi excels because, due to sharp blade and long handle, and employing the power of one’s back and legs, it can quickly gouge out large swaths of wood when cutting joints. But make no mistake, for it is not a brutish tool like an axe or adze, but because of the angular control the longer blade, neck and handle afford it can deftly pare fine shavings to achieve precise dimensions for tight fitting joints and smooth finished surfaces, sure signs of the accomplished craftsman.

Sharp tools guided by human hands, controlled by human minds with years of experience are indispensable in the final analysis.

Paring a splice joint with a 48mm chisel

Paring a housed semi-half-lap notch where two beams will cross over and under each other

Indeed, handtools like axes, adzes, chisels and handsaws are necessary especially when doing “ round work” in logs or when the design calls for irregular-shaped timbers. Paring chisels are also needed to achieve the relatively precise tolerances and smooth surfaces such work demands.

Ootsuki nomi are relatively heavier than other Japanese paring chisel with larger diameter and longer handles. They are built to resist the large bending moment forces created by a large man gripping the handle with both hands and pushing like a plow horse to pare wood. This is the task this chisel excels at.

Most Japanese carpenters that use this tool buy them in sets of two: a wide 48~54mm wide one for paring open joints and the sides of mortises, and a narrower 24mm chisel, although other sizes are available. I have owned a custom 2-pc set hand-forged for me by Mr. Shimamura (Kiyotada) many years ago, one with a 60mm blade and an extra-large handle intended for working especially large North American timbers.

The 24mm chisel is used for paring standard rectangular mortise, dovetail mortises and dovetail tenons, besides a hundred other tasks. In cross section, it is essentially a large shinogi usunomi chisel to help it get into tight places.

A carpenter paring the end walls of a mortise with a 24mm ootsukinomi chisel

Mitsuura

When paring large surfaces with the wider ootuskinomi chisel the hollow ground ura may allow bumps to slide in the hollow-ground ura unseen escaping paring requiring multiple passes to knock them down. This sneaky behavior is easy to overcome with practice, but some people prefer an ura with not a single, but multiple grinds with lands between each hollow-ground area to help index the blade and shave these bumps the first time.

I believe this is one of the few situations where these multiple ura, called mistuura or “triple-ura” are useful.

Kensaki (swordpoint) Ura by Sukemaru. A very unique style of mitsuura cut with EDM equipment. Pretty cool, huh. Sadly, Mr. Usui no longer does this detail no many how hard I beg him to.

Some people like the unusual appearance of mitsuura. I must admit they look sexy in wide blades, but they have some downsides. The first downside is that, because there is more hard steel in contact with the stone, mitsuura blades can take a little longer to sharpen.

Second, they can be a little harder to keep flat. Neither of these are difficult problems to overcome. But the third downside is more problematic.

Because the three hollow-ground areas are shallower and have less total volume than a single ura, they tend to wear out and disappear sooner. This is not a serious deficiency unless you use and sharpen a mitsuura chisel a lot, or have a heavy hand when sharpening the ura. The negative impacts are minor in most cases.

Beloved Customers need to be aware of these peculiarities and to be gentle when sharpening mitsuura blades.

C&S’s 24mm Ootsukinomi. Notice the shinogi shape

These are not chisels most people will ever have need of but as long as humans are doing timber framing, there will always be a demand for this unique tool.

YMHOS

If you have questions or would like to learn more about our tools, please click the see the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.

Please share your insights and comments with everyone by using the form located further below labeled “Leave a Reply.” We aren’t evil Google, fascist facebook, or thuggish Twitter and so won’t sell, share, or profitably “misplace” your information. If I lie may the bird of paradise poop on my face.

Links to Previous Posts in this Series

The Ancient Art of Hand Forging

Those who hammer their guns into plows, will plow for those who do not.
Thomas Jefferson

Hand forging is an ancient blacksmithing technique that, from the viewpoint of cutting tool performance, has been almost entirely replaced in modern times, but never surpassed. Understanding a little bit about this technique and its history is helpful in understanding what a good blade should be.

Before motor-powered machinery and gas-fired forges, steel was very expensive. It took a lot of expertise, fuel, manpower and endless hammering over long periods of time to turn rocks into useable pieces of steel, an economical reality that shaped civilization for millenia. International economics aside, all steel was of necessity hand-forged back then.

This is not an efficient process compared to drop forging or press shaping. It consumes more time and fuel, and requires more labor, skill and experience. It is contrary to modern mass-production methodology. It’s a job for a trained blacksmith who demands a fair wage, not a seasonal factory worker in Bümfüq Guangzhou intent on earning enough cash to put a new corrugated sheetmetal roof on his family hovel in the countryside.

In the final analysis, hand-forging is both unprofitable for corporations and too expensive for consumers who actively value low cost and appearance above performance. No wonder it’s as Dead as Disco.

You may recall people talking about how they prefer to use hand-forged antique chisels and planes because they are superior. Those old tools certainly don’t look superior to modern tools, and they aren’t cheap. But are they superior? And if so, why?

The essence of hand forging is using hammer, tongs, anvil and forge (charcoal/gas fired) to violently shape the metal during a series of heating and cooling cycles. The combination of hammer impacts and repeated heat cycles (heating, cooling, reheating) breaks the relatively isolated, large clumps of carbide crystals into uncountable small crystals, distributing them more evenly throughout the steel’s matrix, producing the sharper, more durable, and most desirable “fine-grained” steel.

The properties of this steel are what make it valuable.

A “Tatara” furnace in Japan used to create a “bloom” of “Tamahagane” steel from “satetsu” which translates to “sand iron.” This is the traditional steel that was used throughout Japanese history prior to the importation of Western steel from England in the 1860’s

A clump of Tamahagane *(“Jewel Steel”)* as it is sold from the bloom furnace. It contains lots of voids and impurities that make this material entirely unusable in modern tool-manufacturing processes.

Related image — A clump of Tamahagane early in the forging process. Most of this material will be lost as waste before a useful piece of steel is born.

After the Blacksmith hammers the raw clumps of Tamahagane hundreds of times, he then forms it into numerous small flat steel patties, which he breaks into the pieces shown in this photo in preparation for forge-welding them into a single larger piece of steel that he can then forge into a blade.

Let’s examine some of these coveted properties. The first is is that it is tougher than steel of lesser quality, meaning it is less likely to fracture due to crystalline defects. In the case of swords or knives it means the blade can cut and chop without breaking when subjected to stresses that would destroy a blade made of lower-quality steel.

The second and third ways fine-grained steel is superior is related to the first. The consistent crystalline structure with its finer carbide crystals distributed more uniformly throughout the matrix results in a cutting edge that can be made sharper, and that will retain that sharpness longer than steel of lesser quality. Of course, realizing this performance depends on the quality of the materials employed, and the skill and diligence of the blacksmith.

Many antique tools were made during a time when steel was expensive, and hand-forging was the only way to shape it. In fact, in the case of critical tools such as swords, this process included forging and reforging clumps of impure iron, folding and refolding the resulting mass into itself hundreds of times to remove impurities and adjust the carbon content, typically resulting in the a loss of 75+% of the original material’s mass. That’s a lot of material and manpower tossed onto the ash pile.

I call these tools critical not just because of their important functions but because of the implied warranty that went with them. For instance, if such a blade failed in battle, the blacksmith’s implied warranty went beyond financial compensation and involved the loss of his body parts at the hands of his vindictive customer’s surviving family members. How’s that for an “extended warranty?”

But any decent steel cutting tool was time consuming and expensive to produce. Until quite recently, blacksmiths did not have tools such as infrared temperature gauges, oxygen sensors, or hardness testers. All they had were their hands and Mark 1 Eyeball, so it took many years of training under a master for a blacksmith to learn how to make a good blade and survive.

Quality control was a big problem back then, but the blacksmiths in Scheffield, Philly, Solingen, Fukuoka and elsewhere still managed to make excellent blades of all varieties with fine-grain steel as the customer demanded. Most of those surviving blades are superior to what is manufactured in the West today. Certainly better than anything made in Chinese factories.

Unfortunately, it is impossible to judge a piece of steel’s crystalline structure with the naked eye, a fact mass producers exploit nowadays to make huge profits selling low-quality tools made from scrap at relatively high profits based solely on the tool’s appearance as it hangs on the hardware store wall encased in its impermeable armor of clear plastic. Lower-quality tools became widely acceptable once a generation or two of consumers that knew the value of cutting tools hand-forged from high-carbon steel left for the big lumberyard in the sky to be replaced by more urbanized generations that valued low cost and appearance more than performance.

Sadly, while the quality, consistency, and workability of steel as a material has greatly improved, the ancient technique of hand-forging has been abandoned throughout most of the world, skilled blacksmiths are almost extinct, and blade performance has suffered as a direct result.

Hand forging is still practiced by some blacksmiths in Japan, where the greater quality and performance this technique provides are still highly appreciated by craftsman obsessed with performance. Accordingly, our chisel and plane blades are made from modern high-quality high-purity steel produced by Hitachi metals instead of the much more expensive and difficult to work traditional Tamahagane. However, our blacksmiths hand-forge every single blade in their one-man forges through a minimum of three heats to form a fine-grain steel with the characteristics noted above that Japanese professional woodworkers demand.

éã®è£½é å·¥ç¨ — A composite photo of Nakano Takeo forging a plane blade.

YMHOS

If you have questions or would like to learn more about our tools, please click the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.

Sharpening Part 13 – Nitty Gritty

“The true mystery of the world is the visible, not the invisible.”
Oscar Wilde

In this post we will dig into a few important nitty gritty points about sharpening stones everyone needs to know. Perhaps Beloved Customer already knows all these points, but please ready your shovel because there may be at least one buried surprise.

A Wood Shavings-Eye View

When seen under high-magnification, the surface of a sharpening stone looks like millions of densely-packed stones embedded in a flat field. The smaller the stones, the finer the grit.

As the blade is pushed and pulled over these stones, they scratch and tear metal from the blade’s surface leaving behind scratches corresponding to the size of these small stones. This violence continues until the blade’s ura and bevel form a clean intersection of two planes.

A view of a blade sharpened with 1200 grit diamond plate showing the furrows left by individual pieces of grit

Seen under high-magnification, the cutting edge is jagged where these furrow-like scratches terminate at the cutting edge. To some degree, it may even look like a serrated sawblade. Some blades, like kitchen knives and swords, are used in a slicing motion to cut soft materials like meat and vegetables and enemy arms, and their performance benefits from a serrated cutting edge more than a highly-polished edge, and so do not need to be highly polished on fine-grit sharpening stones.

Plane and chisel blades, however, are used to cut wood, a material typically harder than foodstuffs, in a straight-on direction, not in a slicing motion, for the most part. In this situation, a rough, serrated cutting edge is weaker than a highly polished edge because the jagged edges are projecting out into space like the teeth of a handsaw blade, and are relatively unsupported and more easily damaged than a highly-polished blade with smaller, more uniform scratches terminating more cleanly at the cutting edge.

Therefore, in order to produce a sharp durable blade, we must make the microscopic cutting edge smoother and more uniform by using progressively finer grit stones to produce shallower and narrower scratches, and a thin, uniform cutting edge.

But how fine is fine enough? There is a curious phenomenon related to friction that is applicable to cutting edges, and is useful to understand.

The Friction Paradox

Imagine a cube of heavy, polished stone with its downward flat face resting on the level, flat surface of a larger slab of similar stone. Let’s say it takes some specific measure of force pushing horizontally on the stone cube on top to overcome the static force of friction between the two stone surfaces in order to make the cube start moving.

If we gradually increase the degree of polish between the two contact surfaces and measure the force required to start the top cube moving at each progressively higher level of polish, we will find the force decreases with each increment of increased polish, at least for a time. This is at least partially because the irregularities between the two surfaces (asperities) do not interlock as deeply when the surfaces become more polished.

However, at some point, more polishing brings the surfaces of the two stones into such intimate contact that the molecular attraction between them, and therefore the force necessary to move the cube, actually increases.

The same phenomenon occurs with tool blades. If you sharpen and polish your blades past a particular point, the friction and heat produced during the cut between blade and wood will increase, as will the energy that must be expended, while the resulting quality of the cut and durability of the cutting edge will not improve significantly. Of course, the time and money invested in stones spent sharpening past this point will be mostly wasted.

The Inflection Point

The inflection point where additional polishing yields increased friction with little improvement in cut quality will depend on your tool and the wood you are cutting, but you can get a pretty good idea of where it is if you pay attention over time. While the sharpening stone manufacturers turn red in the face and salesmen froth at the mouth and spray spittle in anger when I say it, in my well-informed opinion there is little practical gain, beyond self-satisfaction, to be had from sharpening chisels or planes past 6,000~8,000 grit, making this range of grit an inflection point in my mind. What about you?

Conclusion

I encourage Beloved Customer to conduct your own experiments to determine the inflection point in the case of your planes and wood you cut. Many who figure this out save themselves significant amounts of time and money sharpening over the long-term.

To those Gentle Readers that love sharpening more than woodworking, and enjoy putting money in the pockets of sharpening stone manufacturers more than keeping it for themselves, I apologize for pointing out the icky floater in the punch bowl. But you probably would have it noticed it eventually anyway, if only from the taste difference.

I will touch more on this important point in the next exciting installment in this scientificish adventure.

YMHOS

If you have questions or would like to learn more about our tools, please click the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.

Links to Other Posts in the “Sharpening” Series

Sharpening Part 12 – Skewampus Blades, Curved Cutting Edges, and Monkeyshines

A famous wood carving of 3 monkeys located at Nikko Toshogu Shrine post re-construction that illustrates a famous saying originating in China that also works as a pun in the Japanese language. From right to left: *See no evil*; *Speak no evil*; Hear no evil (見えざる、聞かざる、言わざる).

Even monkeys fall from trees (猿も木から落ちる)
Japanese saying

Ideally, a tool blade will have absolutely uniform dimensions: the right thickness and taper, perfect cross-sections, uniform curvature, and straight edges and surfaces. However, professional grade Japanese tools are not made on CNC machines, but are hand forged with dimensional imperfections. Indeed, imperfections are part and parcel of all human endeavors. Most imperfections don’t matter; Sometimes they make the tool better; Other times they need to be remedied.

Beloved Customer may not notice that the blade or cutting edge of one of your chisels or planes is “skewampus,” and not understand why these irregularities produce cutting results that are less than ideal. You may blame those poor results on the presence of pernicious, predatory pixies, your technique in using the tool or even on the irregular grain of the wood you are working, when the real problem is the shape of the blade’s cross-section, or perhaps your unintentionally sharpening the blade with a skew. We will examine some of these problems in this installment in our series of romance and adventure.

We will also look at the curved or “cambered” cutting edge profile in plane blades, the benefits and undesirable results it can produce, and how to incorporate this blade profile intelligently into your woodworking repertoire.

Many people, like monkeys in trees, learn bad habits from their friends and teachers. We hope this post will help you understand what is going on with your woodworking blades, and how to shape and sharpen them intelligently instead of just monkeying around. Please be sure to BYOB (bring your own bananas).

A serious craftsman doing Fine Woodworking in a Pixie-free workshop (notice the strategically-placed boots).

Dealing With Skewampus Blades

Skewampus is an interesting word I learned from my mother. I am told it is a combination of the word “Cattywampus” meaning “in disarray,” and “askew.” I think it is the perfect word for describing the ailments some blades suffer.

While less than ideal, it is not unusual for the thickness of a chisel blade’s cross section to vary slightly across its width, with one side being thicker than the other, forming an irregular quadrilateral cross section. This irregularity is found in plane blades too. Since there is more steel on the thicker side of such a blade, unless care is taken, it will abrade differentially and tend to develop a skew during sharpening.

As discussed in previous articles in this series, Japanese plane and chisel blades are formed by laminating a layer of hard steel to a much softer body made of extremely low-carbon steel or iron. If the lamination exposed at the cutting edge is not uniform, the area of the blade with more hard steel touching the sharpening stone will abrade slower than areas with less exposed hard steel such that the cutting edge will tend to become skewed during sharpening. Perfection is unattainable, but the uniformity of the lamination is an important detail to observe when purchasing Japanese tools.

Likewise, Western plane and chisel blades that are not uniformly heat-treated, and that exhibit differential hardening across the bevel’s width, will also tend to become skewed during sharpening as one side of the bevel abrades quicker than the other. This problem is more common than you might imagine, especially in the case of inexpensive tools where appearance and low price are given priority over quality.

Anyone that has experience bidding high-dollar construction projects will understand the adage “the most profitable job may be the one you lose.” Cheap tools are much the same way: that low-cost chisel or plane may look good on paper and even during the unboxing ceremony, but if you count your time worth anything, if you dislike headaches, and real-world performance matters to your bottom line, then such a tool is often disastrous. Caveat emptor, Skippy.

A chisel or plane blade that has an irregular cross section or a skewed cutting edge may not be a problem for many cutting operations. However, when cutting mortises, a chisel blade with a skewed cutting edge or irregular cross section will tend to drift to the side gouging the mortise’s walls and ruining tolerances. If you find that your mortise walls are gouged, or that tolerances are poor, check your chisel blade’s shape, and correct any deformities. It usually isn’t difficult to do.

Like all human work spaces, Japan’s smithies are not immune from pixie infestation despite annual blessings by Shinto priests and periodic offerings of salt, rice, and wine to the spirits. I will refer you to this previous post and another wherein we discussed supernatural predators and described some antidotes for the pixie pox. But the deformities we are examining in this post are more often the natural result of the human eye misjudging hammer blows or non-judicious use of grinder wheels rather than precocious pixies at play.

If your blade’s deformity is not excessive, you can compensate by applying a little extra pressure on the blade’s thicker side while sharpening it.

It is interesting how a little off-center pressure on a blade being sharpened over many strokes can change its shape. Many people unintentionally deform their cutting edges by not paying attention to the amount and location of the pressure their fingers apply. A word to the wise.

Another potential solution is to skew the blade in relation to the direction of travel when sharpening the bevel. This works because the leading corner of a skewed blade is abraded quicker on the stones than the trailing corner. But once again, inattention causes many people to skew their blades when moving them around on their sharpening stones unintentionally creating, instead of intentionally correcting, skewed cutting edges. BTW, there’s nothing wrong with skewing the blade when sharpening so long as you are aware of the distortion this practice can produce and compensate accordingly. Another word to the wise.

If these methods don’t compensate adequately, you may want to grind and lap a chisel blade to a more uniform cross-sectional shape. A chemical bluing solution used afterwards will help conceal the shiny metal exposed by this operation if your chisel objects to shiny spots. Some of them can be quite vain, you know.

A chisel with a an adequately uniform lamination and cross-section, and nice polish.

Cutting Edge Profiles

Many people have access to electrical jointers and planers, but relatively few have industrial equipment with the capacity to dimension wide boards such as tabletops. And of course architectural beams and columns are typically too long or too heavy to dimension with most stationary electrical equipment.

The choices available to most people for dimensioning such materials therefore are either handheld electrical power planers and/or sanders, or axes, adzes and hand planes. Powerplaners, sanders, axes and adzes are beyond the scope of this article, but we will look at hand planes.

I need more than one plane? You can’t be serious!

Although the very idea gives some woodworkers vapors (I don’t mean gas), an efficient craftsman will have multiple planes with cutting edges honed to profiles matched to specific operations. It doesn’t take many but it does take more than one, unless you intend monkeyshines.

Everyone that dimensions larger pieces of lumber by hand needs a plane with a wide mouth and a curved or “cambered,” cutting edge called a “scrub plane” in the West, and “arashiko kanna” in Japan.

This variety of plane excels at hogging a lot of wood quickly when the craftsman needs to significantly reduce the thickness of his lumber. If the blade is narrow, curvature is deep, and the mouth is wide this plane will hog wood quickly, but leave a deeply rippled surface, often with bad tearout.

One might also have a second arashiko, or jack plane with a wider blade with a shallower curvature for the next steps in the dimensioning process. Such a plane will not hog wood as quickly, but it will produce a surface that is closer to flat and smoother with less tearout. You can see the advantage of having two arashiko planes, or a scrub plane and a jack plane, with different cutting edge profiles when dimensioning lumber.

Many Beloved Customers use electrical-powered planes to dimension lumber before turning it into furniture, doors, chairs, or sawdust, etc. and are aware that planers always leave tiny ripple-like scalloped cuts on the wood’s surface, along with some tearout. This will not do as a final surface. A hand-planed finish is far superior, but it doesn’t make sense to remove any more than the bare minimum of wood necessary to remove the washboard.

A finish plane, in fact, is the perfect tool for this job on condition that it is sharp, set to a fine cut, the chipbreaker is tuned and set properly, the blade profile is appropriate for the width of the wood to be finished, and the wood does not have too many large knots. In one or two passes such a plane can easily remove all the ripples and leave the wood clean and shiny without changing its dimensions much at all.

Assuming the wood is cooperative and one knows how to sharpen and setup their plane properly, blade profile frequently remains a key factor many fail to grasp. Obviously, the curved cutting edge of a scrub plane cannot produce the perfectly flat surfaces required for joining two pieces of wood together. On the other hand, the corners of a perfectly straight blade will leave clearly visible steps or unsightly tracks on the surface of a board wider than the blade, which is not a problem when rough-dimensioning a board, but is painful to look at if the board’s surface is to be left with just a planed finish.

So how do we solve this conundrum? When finish planing, the professional approach is to use two planes each with a different cutting edge profile.

The first type of finish plane has a perfectly straight cutting edge used to plane pieces narrower than the blade’s width. Since the blade’s corners are not riding on the wood but are on either side of the board while cutting, they won’t leave tracks or ridges.

The second type of finish plane found in the professional’s toolkit has a curved cutting edge, or more correctly, curved just at the right and left corners to prevent it from leaving tracks and ridges when planing boards wider than the blade. Nearly all the cutting edge is left straight, but creating this tiny amount of curvature at the right and left corners causes them to smoothly disappear into the plane’s mouth so no tracks are made and any ridges are nearly impossible to see or feel. In other words, the corners of the cutting edge never touch the surface of the board, and so don’t leave discernible tracks or ridges. The finer the cut made the smaller any ridges created will be. Indeed, where a high-quality surface is required, the final cut with the finish plane will produce shavings thin enough to see one’s fingerprints through.

You may want to reread the previous two paragraphs to make sure you understand what these two cutting edge profiles are and what they can accomplish before you read further.

Naturally, a professional doing high-quality work needs at least two finish planes, one with a straight cutting edge used to produce flat, precisely-dimensioned surfaces on wood narrower than the blade’s width, and another finish plane with a cutting edge very slightly curved at the corners used to finish surfaces wider than the plane blade.

There are those that advocate using a curved blade, sometimes dramatically “cambered,” as some call this shape, for all applications. Those who advocate this sloppy technique twist themselves into knots justifying tricks to approximate flat surfaces using such blades. I have no doubt this is an ancient technique, but I suspect it is a sad practice that sprung from the carelessness of some craftsmen in flattening their sharpening stones, and with time this bad habit became a tradition in some quarters. I strongly suspect fans of this strange way of doing business habitually sand all visible surfaces anyway so tracks and ridges are not a problem for them. But the fact remains that perfectly flat, track/ridge-free surfaces work best for joinery.

Tradition and “monkey see monkey do” are a useful place to start, but as his skill level increases, the thoughtful and efficient craftsman will eventually seek to confirm the validity of the traditions he has been taught. I urge Beloved Customer to get started early.

Sadly, too many people never notice the strange instruction label pasted to their boot’s sole, nor that smelly stuff sloshing around inside.（ツ)

Mommy monkey teaching baby monkey bad habits. When will they ever learn?

Conclusion

As we come to the end of this article allow your humble servant to leave Beloved Customer with a word or two of advice about two bedrock basic skills you should master.

First, learn how to keep your sharpening stones flat. This will save you much grief.

And second, learn how to sharpen your blades to have a straight cutting edge. Everything else will flow naturally from these skills. Your blades deserve it. We will talk more about these subjects in the future.

In this post, we have discussed 12 serious points about plane and chisel blades and how to use and improve them all but a few woodworkers in the West are unaware of, or ignore, but which are common knowledge among professional Japanese woodworkers in advanced trades. While condensed, it is enough information to fill a book. But all I ask are the bananas you have in your back pocketses right now (BYOB, remember?).

We hope you picked up on each point, and test those that are new to you.

The next installment in this simian soap opera of sharpening will focus less on monkeyshines, and more on stones and techniques. Please stay tuned. Until then, I have the honor to remain,

YMHOS

If you have questions or would like to learn more about our tools, please click the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.