Sharpening Part 19 – Maintaining Sharpening Stones

砥石の面直しについて :鑿研ぎ練習 番外編_e0248405_17182931.jpg

Give me six hours to chop down a tree and I will spend the first four sharpening the axe.

Abraham Lincoln

Sharpening stones must be maintained if they are to perform effectively. Abe Lincoln’s quote above is especially relevant to this subject.

There is a lot of hogwash taught as holy gospel on this subject, so in this article your humble servant will suggest some more or less traditional methods that both work well, and are cost-effective. Do with them as you will.

Key Principles

Let’s begin with a few basic but critical principles about sharpening that Beloved Customer should understand and use:

  1. For the majority, but not all, applications, your blades need to meet the following standards:
    • Flat back/ura: perfection is not necessary but it must be flat enough for you to be able to consistently polish the last few millimeters of steel directly behind the cutting edge on your finishing stone;
    • Flat bevel, for the same reason mentioned above;
    • Straight cutting edge (except when a curved cutting edge is required).
  2. All Stones get out of tolerance with use. Working a steel blade on a sharpening stone of any kind, whether waterstone, novaculite, coticule or carborundum, wears the stone a little bit with each stroke, creating a dished-out, twisted surface to one degree or another, even if you can’t detect the distortion with Mark-1 eyeball. Therefore, you need to frequently check the flatness of your stones when in use and true them when necessary;
  3. Despite what many imagine, a hollowed-out stone cannot reliably maintain a blade with a planar ura, a flat bevel, and a straight cutting edge, but it can damage the blade being sharpened.

The Rule of Seven applies, so reread these three critical points three times, click your heels three times, and ask the gods of handsaws to help you remember them.

Albrecht Dürer - Melencolia I - Google Art Project ( AGDdr3EHmNGyA).jpg
Melencolia I by Albrecht Dürer 1514
What are the angel and her little buddy pondering? Sharpening, no doubt.

Pretty simple stuff, right? I apologize if Beloved Customer already knows these things, but you would be surprised how many people know them but still ignore them, and then wonder why their blades won’t behave. Iron Pixies? Nah. Perhaps Mifune Toshiro said it best in Akira Kurosawa’s movie Yojimbo when he quoted the old Japanese proverb: “There’s no medicine for foolishness” (馬鹿に付ける薬はない).

Toshirô Mifune in Yôjinbô (1961)
A scene from Akira Kurosawa’s classic movie Yojimbo (1961), the inspiration for the later spaghetti westerns beginning in 1964 and even the more recent TV show The Mandalorian. In this scene, the nameless loner anti-hero is warning off some hired ruffians who have bragged about their tattoos and the death sentences hanging over their heads and informed him they aren’t afraid of him or the pain of being cut. The hero responds with the proverb “There’s no medicine for a fool,” then tests their resolve by cutting 3 of them. Ouch! A hard lesson easily avoided. BTW, if you have tattoos and visit Japan, best to keep them covered since they have an old and indelible association with criminal organizations and judicial branding. On the other hand, if you enjoy being mistaken for a lowlife, violent, thieving piece of scum, by all means show off your ink.

Here’s the scene on YouTube. Please don’t watch it if you are squeamish. Never call the Man With No Name’s bluff.

Yôjinbô (1961)
The Man With No Name (aka Kawabatake Sanjuro played by Mifune Toshiro) pondering the interesting financial opportunities awaiting him in the troubled little post town. His older swordsmith friend (Tono Eijiro) bitterly objects to his plans. The old boy was right.

Although it has only happened once or twice in my recollection (my saintly wife of the jaundiced eye may disagree (ツ)), on those few occasions when I have made a stupid mistake I have been known to ask subordinates to fetch a large bucket of “Idiot Salve” for me from the drugstore. The jury is still out on the effectiveness of this ointment, but I would like some credit for writing this entire article without applying any.

But I digress.

Obviously, if every stroke wears the stone a little, then we must constantly check our stones with a stainless steel straightedge for flatness (length and width) and wind (diagonals) as we use them. It takes 3 seconds. Even if your stones are brand new, you may find distortions. Time spent checking is not wasted if it results in improvement, which it usually does. This is the heart of quality control, and is applicable to everything in life.

Truing Stones

When your check reveals the stone is out of tolerance, you need to flatten/true it. Don’t put it off.

There are many ways to get this job done. Some people advocate using diamond plates to flatten stones. Others insist that sandpaper is best. And then there are the specialty flattening stones. It ain’t rocket surgery. All these methods work, but are unnecessarily costly and time consuming in my humble opinion. The following is the procedure I use and recommend. Give it a try, Beloved Customer, before you dismiss it.

  • Always have two of each of your rougher stones soaked and ready to go when you start sharpening, space and weight permitting. This means 2 – 1,000 grit stones, and 2 – 2,000 grit stones in my case. If you use your tools, owning these extra stones is never wasted money.
  • If the blade is damaged, for instance chipped or dinged, begin with a rougher stone or diamond plate, whatever you have that will waste metal quickly and easily while keeping the blade’s bevel flat.
  • If your blade is not damaged, begin the sharpening process with a fresh, flat stone, for instance 1,000 grit. Turn the stone end-for-end halfway through the estimated number of required strokes and continue sharpening. Yes, you need to keep track of your strokes, at least approximately. This will become second nature with practice.
  • Occasionally check the stone for dishing and wind using your thin stainless steel straightedge. With practice you will develop a sense of the stone’s condition without the need to use a straightedge, but check anyway. Stop using the stone when the distortion becomes noticeable. 
  • Switch the distorted stone with your flat stone of the same grit and continue sharpening. 
  • When both stones of the same grit become distorted to the same degree, cross-hatch the faces of both with a carpenter’s pencil, then rub them against each other under running water if possible, or while frequently adding water if not. Take short strokes and be careful to apply even pressure to the stones. This requires self-control, switching the stones end for end frequently, and making an effort to apply even pressure with your hands, and is more difficult than it sounds until you get used to doing it. The friction and water will wear the high spots down, I promise.
  • Monitor the pencil marks to track progress.
  • Check with a straightedge frequently, and stop when both stones are flat, or maybe even a tiny bit convex. 

With practice, and if you don’t let your stone’s condition get out of hand, this process should take only a few seconds, but it will ensure you are always working on flat stones.

If you think this technique is slower than using a diamond plate, specialty flattening stone, or sandpaper, you may be overlooking a key point, namely, that using this method one can flatten two stones at the same time, in the same time period, and with the same hand movements. It may be slower than flattening a single stone with a diamond plate, but it is definitely quicker than using the same diamond plate to true two stones one at a time. Think about it.

It’s also cheaper because diamond plates are costly, and wear out. The specialty flattening stones are not cheap, and they too wear out. Both methods can contaminate stones, in my experience. And sandpaper wears out quickest of all and is the most expensive method long-term. No-brainer.

Now you have two stones of the same grit on-hand that are flat, free of contamination, and ready to rock-n-roll without wasting time or money on diamond plates, sandpaper, or special flattening tools. This means you have four fresh, flat surfaces at the beginning of the work day to use before you need to take time away from your paying job. And if you pay attention when sharpening, and take care to use each stone’s entire face, the time between sharpening sessions can be increased while saving significant amounts of cashy money.

Finishing stones seldom require flattening, but the same procedure can be used when necessary. A better solution is to the use the float-glass lapping plate described next.

If you need to get a stone extra flat, rub the stone on the  ⅜~1/2” (9~12mm) or thicker plate glass mentioned in the previous post. You can often bum scrap pieces of glass from glass stores or contractors. Dumpster diving behind a glazing shop may prove useful if you are careful and don’t cut your arm off. Don’t forget to remove the sharp corners and edges with a carborundum stone or you might end up like the annoying guy in the video linked to above.

To turn the plate glass into a lapping plate, aggressively roughen one side with a carborundum stone or diamond plate, and clean it thoroughly with a scrub brush, soap and running water to remove every trace of glass and stone particles. Then clean your brush and scrub the glass again. These scratches you just made will turn it into an inexpensive and efficient lapping plate. Trust me. Just wet the glass and rub the stone on it while rinsing frequently. Try to use the entire surface of the plate, not just the center. And be sure to apply uniform pressure to the stone

If a stone becomes grossly distorted, you can use a rougher stone or diamond plate to true it. Even a concrete sidewalk and garden hose will do the job. However, if you do this, remember that there is no way to avoid contaminating the finer stone with embedded grit from the rougher stone or concrete. This embedded grit must be dealt with before using the stone.

To remove the offending stone particles, scrub the stone’s faces, sides and ends with a rough bristle brush under running water. Finish by polishing the stone’s face with a nagura stone, and rinsing well.

You should also use your nagura stone frequently to dress and true the faces of your finishing stones.

Don’t forget to maintain the edge chamfers on your stones and keep them free of contamination and pixies too.

As with all things, moderation is best. A perfectly flat stone is expensive to maintain and not especially better for general woodworking than a pretty-flat stone. Beware! For this rabbit-hole is not only deep, but sleepless nights and gibbering insanity afflict many who strive to plumb its furthest depths.

Rough Stone vs. Finer Stone

Here is an important factoid you should remember: A stone trued using a rougher stone or diamond plate will be effectively of rougher grit than its designation until its surface is worn smooth again. And it will wear faster too. But if you use identical grit stones (same brand is best) to true each other, the effective grit of each will remain unchanged.

Reread the last paragraph three times, click your heels three times, and do that prayer thing again. Namu Amida Butsu.

In this post we looked at inexpensive traditional ways to effectively flatten and maintain our sharpening stones long-term. Now that our stones are looking good, in the next post in this series of hogwash refutation we will be ready to consider how to use them to flatten and polish the ura of our blades. Y’all come back now y’hear.

YMHOS

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I don’t want to hear no more cracks about hogwash. You said to clean the stones, didn’cha!?

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 a family of hogs move into my shorts.

Sharpening Japanese Woodworking Tools Part 1

Sharpening Part 18 – The Nagura Stone

A Tsushima Black Nagura stone 55x55x55mm

In the previous article in this series your unworthy servant listed some of the tools and accouterments necessary for sharpening Japanese tools using waterstones. In this article we will examine one especially useful stone mentioned previously: the Nagura. I know, it sounds like the name of some smelly, creepy thing that crawled out of a mountain cave in Angmar in Middle Earth, but if you don’t have this little stone, you should get one.

The Nagura Stone

Nagura stones have been used in Japan for millennia, but they are not unique to Japan. For instance, the Coticule stones of Northern Europe have been used with nagura-equivalent stones since before Roman times. And I would not be surprised if the same tradition existed elsewhere too, they are so useful.

Mikawa Nagura Stone

There are several varieties of Nagura stones mined in Japan, the two most popular being the grey/black Tsushima stone pictured above and the softer white Mikawa stone pictured below. I use a soft white Mikawa Nagura stone for my straight razor.

The black Tsushima variety is cut from sedimentary stone on the ocean floor near Tsushima in Nagasaki Prefecture, located midway between Japan’s Kyushu island and South Korea. I believe it to be the best for general usage so I will discuss this stone in particular.

Like all Japanese natural stones, Tsushima Black Nagura are mined from sedimentary deposits created by airborne volcanic ash being sifted by distance and wind and filtered by waves and tides by the time they reach the ocean floor. But they have not been subjected to the metamorphic weight and heat that makes harder stones, and are relatively soft and permeable. They also tend to crack in the same plane they were laid down in, especially if subjected to wet/dry and/ or freeze/ thaw cycles, so special measures are necessary to protect them.

The Job of the Nagura Stone

The Nagura stone is typically used to perform five tasks.

1. Cleaning Finishing Stones: Finishing stones become contaminated with pixie dust and grit from rougher stones. A 10,000 grit stone with 1,000 grit particles mixed in is much less than 10,000 grit effective. If you think a stone is contaminated, wash it well with a scrub brush and clean water then work the surface with a clean Nagura stone to loosen and float up the contaminate particles, then wash off the slurry. The stone will be clean.

2. Removing Clogging: Similar to 1 above, the Nagura stone is effective at unclogging dried slurry and metal swarth from the sharpening stone’s surface helping it get back to work sooner.

3. Truing Stone Surfaces: Finishing Stones need to be trued occasionally, usually the corners and edges. Use the Nagura periodically to knock these high spots down. The resulting slurry can be used for your normal sharpening process without it all going to waste. This is wisdom.

4. Reducing Startup Time: Time is money. Waterstones abrade most efficiently when they have a slurry worked up, but it can take time to get decent slurry started on some stones, especially hard ones, and with some blades, especially those with soft jigane. Use the Nagura to quickly develop this necessary slurry saving time and money. If you focus on the corners of the stones, which tend to be high anyway, it will contribute to truing the stone as mentioned in 2 above.

5. Reducing the Average Particle Size in the Slurry: Nagura grit is quite fine. You can add Nagura slurry to a stone (by rubbing the stone to create slurry at corners and edges, BTW) to reduce the average grit size of the slurry making a stone create finer scratches and a better polish. For instance, adding Nagura slurry to a 8,000 grit stone makes it polish more like a 9,000-10,000 grit natural stone.

Using the Nagura Stone

Nagura stones are just as useful when sharpening with synthetic sharpening stones as they are with natural stones. In fact, they may be even more useful with synthetic stones since synthetic stone slurry containing nagura particles more closely approximates the performance of natural stones.

Nagura stones are easy to use. Simply wet the large stone and rub the small stone on its surface. You may need to add additional drops of clean water while doing this. The goal is to wear down the high spots on the large stone while at the same time producing a slurry mixture from both stones to use when sharpening blades.

The key is to pay attention, use your handy dandy stainless steel ruler to identify the high spots, maybe mark them with a pencil, and use the nagura on those areas first. Don’t be a ninny and rub the nagura all over the stone willy nilly like you’re washing your pet goat. Make a plan. Work the plan. Develop good habits and speed will follow.

If the large stone is already perfectly flat, and you need to produce a starting slurry, work the ends and corners of the large stone with the nagura in anticipation of those areas becoming high in the near future. That’s a good boy.

Protecting the Tsushima Nagura Stone

Nagura stones are fragile. To avoid water penetration and cracking, it is wise to use the side of the stone that was in a horizontal plane when it was formed. It is also wisdom to use only one surface of the stone and to coat the stone’s other 5 sides with paint to prevent water infiltration and cracking, and to keep skin oils from penetrating. Traditionally, natural urushi lacquer made from an irritating tree sap has been used for this purpose in Japan, but any high-solids urethane will do the job.

The Nagura stone is a subtle tool. As your skill using natural sharpening stones improves the value of this tool will become apparent.

In the next article in this depraved series about sex, drugs and rock-n-roll, we will discuss ways to maintain sharpening stones. Some people will be miffed. Others will be thrilled. Goats will be indifferent. What about you?

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 all my sharpening stones turn to sand.

Sharpening Part 16 – Pixie Dust

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Ashes to ashes, dust to dust, if the women don’t get you then the whiskey must.

Carl Sandburg

In the previous article in the series about sharpening the blades of Japanese woodworking tools we examined sharpening stones, the minimum set your humble servant recommends, those I typically use, and the most important stone in any set.

In this post we will shift our focus to things that can go wrong when sharpening, including supernatural influences.

Dust Contamination

As I mentioned in the previous post in this series I almost never take a 10,000+ grit synthetic finishing stone or natural finishing stone to jobsites. This decision is based on observation under practical conditions: Jobsites are rough and dirty places, and stones are fragile. 

Iron Pixies are rabid fans of Lingerie Football. Don’t hang posters or watch games in your workshop if you want to avoid crowds of the tiny beer-guzzling fiends.

Even if Murphy is drunk and the resident Iron Pixies are distracted watching Lingerie Football on the boob tube (pun intended), airborne dust at the jobsite will always instantly degrade an expensive 12,000 grit rated stone to an effective 4,000 grit or less, making a fragile, expensive, ultra fine-grit stone pointless. How clean is your workplace? Something to think about. Seriously.

This is not just a theory that sprouted from my overactive imagination like a dandelion on a dung pile, but is scientifically verifiable. Give it try.

Get out your microscope or high-power loupe. Place a clean glass slide near where you will be sharpening. 120 minutes later, examine the slide and count the dust specks. How did they get there? Dust is in the air quite naturally, but vehicular and foot traffic kick up lots more.

Most of those dust specs are larger and harder than the grit that makes up your finishing stone. Imagine what happens to your blade when those pieces of relatively large, hard grit get mixed into the stone slurry, or become embedded into the stone’s surface. Not a pleasant thought.

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Dust contamination even has historical precedence. Japanese sword sharpeners traditionally do their best work during the rainy season when there is less dust in the air to contaminate their stones. 

Professionals that polish pianos, stone, glass and jewels are also sticklers for eliminating dust contamination.

Just design and build a few cleanrooms for picky customers with SEMs (scanning electron microscopes), or with lens coating equipment, or who make pharmaceuticals and you will get an education about dust and the problems it creates quickly.

What dust do we find at construction job sites or workshops? First, assuming we are working at a building project, there are exterior sources of dust. Unlike a house, the doors and windows are usually open to gain maximum circulation, even when dusty landscaping operations are ongoing and trucks carrying materials and garbage are running everywhere kicking up clouds of dust.

Second, unless you have the jobsite entirely to yourself, there are usually other trades inside the building grinding, sanding, cutting and walking around kicking dust into the air too. The most pernicious dust on the jobsite is drywall and joint compound. This white fluffy dust appears harmless, but it contains tiny granite silica particles harder than steel, and even bits of glass fiber, that float around and settle on everything. They are a health hazard that has put more than one person in the hospital with respiratory problems. They will contaminate your sharpening stones sure as eggses is eggses.

Sandpaper, sanding discs, grinders and angle grinders in operation also spray millions of tiny hard particles everywhere, many of which float in the air and can travel some distance before settling, especially inside an enclosed building or workshop.

Does your business or home workshop have a large door facing a public road with cars and trucks going back and forth? Do people with muddy boots come in and out? Are dirty pallets with piles of dirt hidden on the bottom boards offloaded inside? Do you use sanders or grinders in your workshop?

If you are sharpening outside, or at a dusty jobsite, or inside a dusty workshop, and especially if you regularly use sanders and grinders there, I recommend the following procedures before you use fine-grit stones:

  1. Try to locate your sharpening area away from foot traffic, grinding and sanding operations, and dusty areas;
  2. Sweep and vaccum the surrounding floors well, since it is the movement of feet that billows settled dust back up into the air, and wait at least 15 minutes after sweeping for the dust to settle before sharpening;
  3. Wet the surrounding ground or floor with water to keep the dust down (this makes a big difference);
  4. Wrap a clean cloth or a sheet of clean newspaper around your fine stone when you are not using it for more than a couple of minutes to prevent airborne dust from settling on it;
  5. Scrub your fine stone under running water with dishwashing soap (neutral PH) and a clean natural-bristle brush before each use to remove dust and embedded grit.

And for heaven sake, even if you can’t take your benchdogs with you everywhere, at least have a brass bevel angle gauge in your toolkit, and use it everytime you sharpen, to keep the pernicious pixies at bay. I hang mine around my neck from a red string, red because all species of the Little Folk strongly dislike that color.

The following are few references regarding silica and construction dust: Silica-Safe.org Center for Disease Control. Makes you want to wear a respirator in bed.

YMHOS

The legal team hard at work digging up dirt. Every one a Harvard graduate, of course.

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 the fleas of a thousand camels infest my armpits.

Sharpening Part 15 – The Most Important Stone

Orders are nobody can see the Great Oz! Not nobody, not nohow! 

Gatekeeper, Emerald City

Many people high-center on this question: “What is the best way to sharpen my tools?”

Your humble, unworthy servant was hesitant to publish this series of articles about sharpening because, beginning with this one, I must write about tools and techniques that are blasphemous to many people’s sharpening religion. Some of those people will doubtless become emotional. As Benny Franklin once famously said: “Ça ira, ça ira.”

The objective of this article is to help our Beloved Customers properly maintain, sharpen and use the blades they purchase from us. But it isn’t a sharpening tutorial; that will be a future post.

We will examine the process of sharpening woodworking tools using mostly waterstones. We will touch on the motivations, goals and priorities related to sharpening you should consider, the minimum set of sharpening stones your humble servant recommends, and my suggestion for the most important stone in your arsenal, one you must be proficient in using.

Motivations

You might have noticed from my previous posts that I like to understand motivations. Am I cynical? Perhaps, but where there are smoke and lights in evidence and money to be made, there is almost always someone behind the curtains spinning dials and pumping pedals. Oooh, pretty lights!

Anyone who does anything has a motive for doing it, and knowing that motive can help us evaluate the validity, and sometimes even the honesty, of what they do, say and write on a particular subject. How can we best ascertain the motivations of those advocating various sharpening methods and related accoutrements? Here are some simple questions you might want to ask: Are the promotions or promoters touting sharpening stones or other stuff they might profit from? Are they selling books on sharpening? Do they teach classes on sharpening? Do they have “sponsors” or “patrons” that supply them, at no cost or with large discounts, stones, diamond paste, sandpaper, sharpening machinery, and/or honing contraptions in exchange for promoting those goods? Are they “influencers” (yes, that’s a real vocation in the NoobTube World) who are compensated for clicks? Do they publish reviews on products they receive for free? You see the pattern.

Regardless of their business model or motivations, many people give good advice, but many are shills, while some are pretenders, and their advice will be colored accordingly. Caveat emptor, Skippy.

And then there is the most obvious motivation. After all, it doesn’t cost even $20 to make a Mechaultrasuperfine Ninja-purple Gold-dust-infused Musashi Walk-on-Waterstone that retails for $650. And have you calculated the long-term equivalent cost of diamond paste and abrasive films? Somebody’s making serious cash.

Just once I’d like to cross the road without having my motives questioned…

Whatever stones you select, I urge you to find a good balance of performance vs cost vs time vs sustainability, with sustainability referring to both the amount of landfill-stuffing the selected process creates as well as its long-term effect for good or ill on your blades. This 4-variable calculus depends not only on the characteristics of the stones and blades you use, but on your sharpening skills too, so it may take years to find the inflection points if you take a scientific approach. The quadratic formula does not yield useful results, sorry to say.

At one time or another I have tried and tested many popular sharpening “systems” including those that rely on jigs, machinery, sandpaper, plastic films, stick, liquid, paste, and powdered abrasives, buffers, strops and even superflat ceramic plates. I enjoy the adventure of learning new things. They all get the job done, and all have serious merits, but to reduce the time and brain damage involved in this calculus, a wise man will learn from no-nonsense professionals, people who have been down the road before and actually use tools to feed their families, and who have no conflict of interest, be it stones, books, or clicks. That’s what I finally did, and I think it worked out well. But I need to issue a disclaimer before we go further.

Disclaimer

Here it is in red letters.

I say what I believe and believe what I say, even if it offends the “gurus” of sharpening. I buy their books and DVDs, watch their YouTube videos, and try their sharpening techniques and even the “tricks” they recommend, so I like to think I am not a “frog in a well,” as the Japanese saying goes. If I don’t know something, I will say so. I am not a liberal college kid to be offended if you disagree with me, but I ask you to not become orcish.

Please note that we do not now and have never received goods, discounts, or financial compensation of any kind from anyone in exchange for modifying our opinion about sharpening tools and techniques.

I have personally taught many people how to sharpen tools over the years, but have never received a red cent for my time and haven’t used those training sessions as an excuse to sell stuff.

I have never done a product review.

I have never written a book or magazine article or even a blog post with advertiser support.

Please note that the document you are currently reading cost you nothing, was written and paid for by C&S Tools alone, and that there are no banners, commercials, or outside links on any of the pages in this blog. No SEO strategy at all. If Evil Google brought you here, it was not at our bidding.

We want to help our Beloved Customers, mostly professional woodworkers who already possess a certain level of skill, to level-up those skills. C&S Tools has no commercial incentive to mislead, and will not do so. But we do have a profit motive.

Remember, we have a 100% guarantee on the materials and workmanship of the tools we sell, so our sole financial motivation, and the very reason for this blog, is to help our Beloved Customers understand the tools we sell, and to become proficient in sharpening, maintaining, and using them so they won’t mistake a lack of skill and/or experience on their part as a problem with the tool. All most professionals really need is a little guidance. We want skillful, ecstatic customers because they become repeat customers. And we do hate to disappoint.

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The Marketing Department

Goals, Objectives and Priorities

I mentioned 4 variable calculus above. Actually, it’s more like 5 variable calculus, the fifth variable being your goals and objectives for sharpening. Let’s examine those in more detail.

If satisfying curiosity are among your goals, then by all means try all the stones, sandpaper, films, pastes, jigs, contraptions, and machines available and methodically test them until they wear away to dust. It simplifies the calculus, but the cost and time required to reach a final conclusion may become a heavy burden.

If beautiful blades, zen-like sharpening experiences, and improved hand-soul coordination are high among your objectives (they’re included in mine), then you will want to try natural finishing stones. I heartily recommend them to those who have reached a certain level of skill with synthetic stones and are willing to roll the bones. The ante may be costly.

The performance of the sharpening system you select, including the following factors, are things you should include in your calculations:

  • Time efficiency: How long does it take you to produce an adequately sharp edge starting from a dull/chipped one? How fiddly is the process? For this calculation you will need to determine how much your time is worth. Remember, while you may enjoy sharpening, from the professional’s viewpoint, time spent sharpening is non-productive time because, during the period you are working on tools, your hands, eyes, and mind cannot work on the stuff you contracted to deliver to the Customer;
  • Cost efficiency: How many billable hours and expensive supplies/tools/equipment must you expend to obtain an adequate cutting edge? For this calculation you will need to determine the cost of time, consumables (stones, sandpaper, film, paste, powder, beer, Prozac) and equipment (grinders, jigs, plates, widgets, etc.) expended in producing an adequate cutting edge long-term. Even if you are not getting paid for your woodworking, your time still has value. And don’t forget to depreciate the cost of stuff. This is where synthetic waterstones shine in comparison to the many other sharpening systems out there, IMHO.
  • Cutting efficiency: How well and how long does the sharpened blade cut? For this calculation you need to determine what defines an “adequate cutting edge” for you. For instance, given the same abrasives and expending the same amount of time to sharpen two blades, the blade with a rounded bevel, or even multiple bevels, is seldom as sharp as the blade with a simple flat bevel, as can be readily confirmed using a powerful loupe or microscope to examine the last few microns of the blade’s effective cutting edge (more on this subject in Part 21 of this series). Does the sharpening system you are testing tolerate or even promote bulging bevels or multiple bevels? Get out your loupe before your inner troll makes you say things you will regret.

If curiosity, pleasure and beauty are lower priority than practical performance in your list of objectives, then I suggest you focus on synthetic waterstones and the bedrock basics, at least for now:

  1. Obtain a minimum set of basic synthetic stones, or adapt what you already have;
  2. Learn how to use them skillfully;
  3. Practice those skills until they seep into your bones.

It is not an expensive process, but neither is it the instant short-term sort of thing the Gurus of Sharpening offer in their books and DVDs and classes through their tricks and gimmicks. It takes real skills that will serve you and your tools well for your entire life. And it all starts with the minimum set of stones.

The Goldilocks Set

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Oh my goodness, just look at the time! I really must be going.

Sharpening stones are expensive consumables that disappear a little with every stroke. If you need more than 5 minutes to sharpen a plane or chisel blade that was not chipped or damaged, then you may be spending too long, and wasting your time and stones, so it’s important to determine the bare minimum set of stones that work best for you.

The Goldilocks set I recommend includes the following 4~5 stones/plates:

  1. A Rough Stone: 400~800 grit rough diamond plate/stone or two carborundum stones;
  2. Medium Stones: Two 1,000 grit waterstones (I will get into the reasons for having two stones of the same grit in another post);
  3. A Finish Stone: 6,000~8,000 grit waterstone.

Please also note that, while I use them in my workshop, I don’t consider 10,000+ grit synthetic finishing stones or natural fine-finishing stones essential tools, nor do I take them to jobsites. This decision is based on simple practical experience: Jobsites are rough and dirty places, and stones are fragile. 

The sharpening stones I normally use in the shop include a few beyond the minimum set described above. This set includes more stones, but the idea is that this finer gradation creates a better-quality cutting edge while consuming less of my expensive finishing stones. Natural stones can be pricey:

  1. One 400~800# diamond plate or two rough carborundum stones (only occasionally necessary);
  2. Two 1000# Imanishi waterstones (Bester brand) (usually necessary, but sometimes I skip it);
  3. Two 2000# Bester waterstones;
  4. One 6000# stone (fine enough for quickly finishing chisels and most planes);
  5. Two natural stones for finish planes and push chisels, or just for fun (a 10,000# synthetic stone works just as well).

Which Brand of Synthetic Stone?

I have had good luck with the Imanishi “Bester” brand waterstones. Imanishi seems to be inactive so I have been forced to research other brands. The best alternative I have found so far is the “Hibiki” brand waterstones by Naniwa.

Naniwa also makes an interesting and effective diamond stone they call their “Shrimp Brand,” and which is mistakenly (?) translated as “Lobster Brand” in the US and Europe. Not a “diamond plate,” mind you, but a diamond-impregnated sintered product that works much better than the usual plates with diamond particles electronically attached to steel plates. This diamond stone is comprised of a 1mm layer of diamond grit in a vitrified (baked) matrix affixed to an aluminum plate. The sintered layer is quite hard and won’t dish out easily. More importantly, these plates cut faster, smoother and longer than the diamond plates your humble servant has previously experienced.

It is especially useful for uraoshi of plane blades.

The important thing is to keep it wet in-use. If it becomes clogged with metal swarth, use a nagura stone to clean the surface and get back to work.

The Most Important Stone

Everyone focuses like a laser on the finishing stone, the final stone in the process, but when sharpening a particular blade, the most important stone is really the first stone you use in the series, be it a 400 grit diamond stone or a 2,000 grit waterstone. 

A conventional diamond plate

You may find this whole discussion passing strange, so I will explain. The roughest stone (or diamond stone, depending on the amount of steel that must be wasted and your available time and budget) you begin the sharpening process with builds the foundation of your cutting edge by performing the following two critical tasks:

  1. Removing damage at the cutting edge; and
  2. Shaping/flattening the bevel at the cutting edge.

Only a rough stone (400~800 grit) can accomplish the first task efficiently. If the truth of this statement is not self-evident, I won’t even try to convince you. Do the comparisons yourself: count strokes, time, and cost, measure angles, and peep at scratches through a high-power loupe. An opinion based on anything less is just hot air and is less convincing than a California politician’s protestation of not routinely receiving bribes from the many drug cartels that ship product to that hell-hole.

In addition, your roughest stone is also the most efficient tool for shaping the bevel and cutting edge, if it needs to be adjusted. Until these two critical tasks are completed, none of the subsequent finer stones can accomplish anything efficiently, and the faster and more precisely these two tasks are accomplished the sooner one can stop sharpening and get back to making wood chips and shavings.

The role of all the finer stones in the sharpening sequence is simply to replace the deeper scratches left by the preceding rougher stone with progressively finer scratches. And since this work is done using more expensive, less-abrasive and slower-working stones, it is most cost/time-efficient to accomplish this task as quickly as possible.

If you knock out the two foundational tasks listed above using your rough stone/plate well, then you can accomplish the subsequent polishing work at minimum cost and maximum speed. Screw it up and your stones will prematurely turn to mud and your blades will hate you.

Please be sure you understand the meaning of the previous five paragraphs. They are the heart of this article, and should be the foundation of your sharpening process.

So how does this work in real life? If the blade is chipped, dinged, or needs shaping, then I start repairing and reshaping the cutting edge’s foundation with my diamond stone. A carborundum stone, if very flat and kept flat, will work too.

If my blade is only dull, but not damaged, and the bevel is in good shape, I start with a flat 1,000 grit synthetic stone.

If the blade is starting to lose its edge, but is not damaged and still cuts, I start the process with a flat 2,000 grit stone. Notice the word “flat” is used a lot in this article, and not by accident.

The objective, again, is to create an adequately sharp edge in the minimum amount of time and cost by starting the sharpening process with the cheapest, most aggressive stone appropriate to the blade’s condition for the heavy wasting and shaping jobs thereby creating a bevel and cutting edge which you can then quickly polish to the final cutting edge using the more expensive, finer-grit stones. Wow, that’s a mouthful!

I want to make one thing perfectly clear before ending this post. Except for a few special situations, I don’t recommend using secondary bevels or micro-bevels except in special circumstances because, like training wheels on a bicycle, they are not an efficient long-term solution. In fact, they are a short-cut that has stunted many people’s sharpening skills.

We will return to this subject later, but in the meantime, I have the honor to remain,

YMHOS

The Great and Powerful Oz has spoken!

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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

The Repentant Mary Magdalene by Canova

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 frogs infest my boots.