For a change of pace, I would like to share this charming folktale from Kagoshima Prefecture, Japan, of a sort traditionally told to small children.
We originally posted this little story about a year ago, but since those pesky pixies seem to have pulled it down, we are re-publishing it today for Japan’s Labor Thanksgiving Day holiday and because Tengo was such a great workman (or at least labor producer).
I have included photo extracts from the Kasuga Gongen Genki E (春日権現験記絵) scrolls painted in 1309 on silk using silver and gold paints, showing carpenters working on the Kasuga Temple jobsite.
My children and I enjoyed this story. Perhaps you and yours will too.
The Tale of Tengo and Tenjin
Once upon a time there was a very good carpenter. But he was sad because he lived alone, so he asked the prettiest girl in the village to be his bride.
She did not want to marry, but to put him off without hurting his feelings, she decided to charge him with an impossible task.
“If you will build me a big house with 60 tatami mats in a single day, then I will marry you.” (60 tatami mats = approx 99 square meters = 1065 sqft based on the standard modern tatami mat)
The carpenter was shocked by this demand, but because he wanted her for his bride, he boldly accepted the challenge saying: “I will build you this house in one day.”
His voice rang with confidence as he said this, but he despaired in his heart knowing he could not build such a large and beautiful house in one day. He thought to himself “ What shall I do, what shall I do?”
But never fear, because as you have probably guessed, our carpenter was no ordinary fellow to give up easily. Before long he came up with a plan.
He made 2,000 dolls out of straw and breathed on each while casting a magical spell transforming them all into human carpenters.
The carpenter and his 2,000 man crew then went to work.
With the assistance of his 2,000 helpers, the carpenter completed building his bride-to-be’s house before the sun went down that day,
Overjoyed, the carpenter flew to the pretty girl’s house to tell her of his success. “I have finished the house you asked for. Please marry me now!”
“Truly?” she asked. Upon inspecting the work she found a big, beautiful house with 60 tatami mats, just as she had asked. “I will marry you.” she said.
And thus the prettiest girl in the village became the carpenter’s bride.
The carpenter and his bride then moved into their happy new home.
Afterwards, the 2,000 carpenters scattered throughout Japan to build houses, temples and bridges and teach many other carpenters how to build beautiful things for many years.
After several happy years had passed, the bride said to her husband “I have been silent up to now, but the time has come to tell you the whole truth. I am not really a human being, but an angel named Tenjin. I came down to earth from the kingdom of heaven. But the time has now come for me to return to heaven.”
The carpenter replied: “Ah, well, now that you mention it, I’m not a human being either, but a carpenter god named Tengo. Let’s both return to heaven together.”
So Tengo and Tenjin rose high into heaven where they still live happily ever after.
If you have questions or would like to learn more about our tools, please use the “Contact Us” form located immediately below. Please share your insights and comments with all Gentle Readers by using the form located further below labeled “Leave a Reply.” We aren’t evil Google, incompetent facebook, or twitchy Twitter and so won’t sell, share, or profitably “misplace” your information.
This post is about a tool that looks quite ordinary but is in fact extraordinary in subtle ways.
Why Do Woodworkers Need a Good Straightedge?
When woodworking we need to be able to mark and measure straight lines and examine the precision of edges and surfaces. There are several ways and tools available to accomplish these tasks, but the steel straightedge is efficient for shorter distances, assuming one’s straightedge is up to the job.
For most woodworking tasks we don’t need a precision straightedge. But for those few activities where it is necessary, nothing can take its place. So what are some of those activities? I can suggest a few from my experience:
I use a precision straightedge as a “Standard” to check that my working straightedges and squares (the ones that are used and abused daily) are truly straight and square. This is necessary because, during use, Murphy governs all operations, while pernicious Iron Pixies dance among the piles of dandruff on his shoulders. Due to their malicious ministrations, measuring and marking tools are easily damaged, wear-out, and lose tolerance so I need a reliable “Standard” to check them against regularly. Of course, you can’t check for straight or square unless you have a truly straight line/surface to index from. It would be silly to imagine that the edge of one’s tablesaw top or jointer table are perfectly straight without first checking it against a reliable standard;
I use a precision straightedge to examine the soles of my handplanes to help me keep them straight, flat and free of wind because it’s very difficult to plane a flat surface with a screwy plane. No matter how much time I invest in truing my planes, I’ve found the results are never better than the straightedge used.
Check that lapping plates and the float-glass plate I use for truing stones and plane soles remain within tolerances. Yes, they wear out too.
Check that the tables of stationary equipment such as tablesaws, bandsaws, jointers, and planers are true, and that infeed/outfeed soles of handheld electrical planers are properly aligned;
Check that surfaces of wooden components of special projects requiring extra precision are true.
Do you ever need to accomplish any of these tasks?
Tasks for Which the Matsui Precision Straightedge is Not Ideally Suited
The Matsui Precision Straightedge is not an expensive tool, but since it is one I rely on, it is most cost-effective to protect it from premature wear and damage, so the following are tasks for which I use a less-expensive and less-protected “working straightedge” instead of my Matsui precision straightedge:
I don’t use it for checking sharpening stones. The Matsui straightedge can do this job with style, but after a few years of being pressed against (and dragged over) abrasive stones, the tool’s precision would be degraded. Better to use a less-expensive straightedge for this job, and check it occasionally against the Matsui Precision Straightedge to confirm it’s still straight. If it isn’t, fix or replace it.
I don’t use it for daily general woodworking tasks. Once again, the Matsui straightedge can do general jobs with style, but after a few years of being pressed against (and dragged over) wooden surfaces, the tool’s precision would become degraded prematurely. Instead I use a “working straightedge” that has been checked against my “Standard” Matsui Precision straightedge;
How To Use a Precision Straightedge for Checking Tools and Surfaces
Neither the human hand nor eye can measure a straight line or a true plane with any precision unaided, but there is one technique older than the pyramids all woodworkers must be proficient at, namely to place a truly straight, simple straightedge on-edge on a surface to be checked, be it a board, a jointer outfeed table, or the sole of a plane, and shine a light source at the gap between the straightedge and the surface being examined. If gaps exist, light will pass between the edge of the straightedge and the surface being checked confirming the surface is not straight and/or flat. The human eye can detect even a small amount of light this way and both quickly and effectively judge how flat the surface being checked is with a surprising degree of accuracy.
Another technique that yields more precise values without relying on Mark1 Eyeball is to place the straightedge’s beveled edge against the surface to be checked, and insert feeler gauges into gaps between the straightedge and the surface. If the feeler gauge selected won’t fit, then one replaces it with thinner gauges until one that just fits is found.
Once you know the value of the gap between your straightedge and the area of the board you need to true, for instance, you can divide the measured thickness of the shaving your planes takes in a single pass (easily checked with a vernier caliper) to calculate how many passes it will take to true the high-spots on a board. eliminating a lot of the guesswork that makes precise woodworking difficult at times.
To reliably perform these checks, we need a truly straight straightedge. Straight is a relative thing, but straightedges sold for woodworking are seldom straight because purveyors rely on purchasers to not bother, or even know how, to check the quality and precision of the straightedges they sell.
Another reason honest, precision straightedges are relatively rare among woodworking tools is that making a high-tolerance piece of hardened steel that is straight, and will stay that way, is hard work that most woodworkers are neither inclined to appreciate nor bother to check, much less pay for. Is ignorance bliss? I believe it is in the natures of our Gentle Readers to always strive to improve the quality and efficiency of their work. A high-quality precision straightedge is an essential tool in that blissful quest.
Challenges & Solutions
The dilemma of the straightedge is that it must be thick and rigid enough to prevent warping and flopping around in-use, but reasonably lightweight and not too bulky or it will be clumsy. At the same time, it must not be too thick, or it will block out most of the light passing between its edge and work-piece making it useless.
Another challenge the straightedge faces is the constant threat of damage. If the delicate edge is too soft, it will become dinged and deformed instantly becoming inaccurate. And if the straightedge rusts (the bane of steel since ancient times), precision will suffer.
What are the viable solutions? They are obvious and proven, but seldom implemented well. Here is how Matsui Precision does it.
Stainless Steel Construction
First, they use high-quality stainless steel to prevent corrosion. If you work in humid conditions or if you will admit to perspiring salt-laden moisture at times, then this is important, but not rare.
Properly-sized, Precision-ground & Polished
This straightedge is not an insignificant piece of stainless steel. It is available in various lengths, but in the case of the Matsui’s 400mm straightedge (a handy, reasonably-priced length), the blade is 34mm wide and 3mm thick, enough to keep the blade rigid in use and prevent warping, but not so wide or thick as to feel heavy or clumsy. It weighs 320gm, a nice balance of rigidity and weight.
Compact, lightweight tools made using quality materials efficiently have a deep genetic attraction to the Japanese people.
What is more rare is the fact that Matsui then precision-grinds and precision polishes the stainless steel (not the same thing) so the tool is as straight and flat as machinists require, because this is a tool designed to the higher standards of machinists, not just woodworkers.
Hardened & Trued
Matsui also hardens the stainless steel to ensure the tool is rigid and will resist wear and damage over its long useful lifespan.
During heat treating and grinding the metal warps slightly. After stress-relieving the tool, Matsui inspects each tool one-by-one and corrects irregularities or rejects those that cannot be sufficiently corrected. It’s called quality control, something that never happens in China or India in the case of tools intended for woodworkers.
To make it easy to see light passing between the straightedge and surface being checked, one edge is beveled. The importance of this detail cannot be overstated.
In the case of the tool we are introducing here, Matsui cuts a small semi-circular notch in the beveled edge of the blade to provide clearance for irregularities in the surface being checked, such as welds, or in the case of woodworking tools the cutting edges of the blades of handplanes, electrical planers and electrical jointers. This is an important and unique feature.
Why is this notch so useful? The problem with using a metal straightedge to check/true the sole of a handplane has always been that, in order to correctly check for flatness/wind, the blade must be set to project from the plane’s mouth the same amount it should be when the plane is being used, because in the case of Japanese planes the wedge-shaped blade applies slightly different pressures on the wooden block at different depths in the block, producing variable degrees of deflection.
But if the blade is projecting from the mouth from the same amount as it will be in use, then the straightedge will ride on top of the blade preventing a proper examination, and at the same time, possibly dulling the blade and gouging the straightedge. The solution has always been to adjust the blade to not actually project, but to be just in-line with the sole, a fiddly process that has resulted in many dulled blades, scratched straightedges, and inaccurate examinations.
With the elegant Matsui Precision straightedge, however, the notch fits directly over the projecting blade avoiding the irritating and time-wasting fiddling normally required to get the blade in the exact position, one that ultimately yields an imperfect reading.
If you need to maintain handplanes, electrical woodworking tools, or do precision woodworking and need an accurate, reliable, lightweight, durable, reasonably-priced straightedge to help take the guesswork out of these jobs, this product is just what you need. I have been using one for years and couldn’t get by without it.
If you are interested, send us a message using the form below.
The time to repair the roof is when the sun is shining.
John F. Kennedy
This article is based primarily on an online discussion with Gary, a truly Beloved Customer, regarding his wise observation about the need to make a toolchest easily repairable, especially if one intends it to be useful for 200 years. I touched briefly on most of these points in previous posts in this series but failed to address the subject of repairability. I would like to clarify a few relevant points in this article.
There are several types of repairs that a faithful toolchest may require during it’s lifetime if it is to remain useful, but I think the two main categories are cosmetic and mechanical. So what did I do to facilitate Moby Dick’s “repairability,” and what would I change to improve it in this regard? Frankly, I gave the subject little thought while designing it, so perhaps you may learn from, or at least giggle at, my mistakes. Soft giggles only, please.
It’s just a wooden box, but it would be wasteful to make it quickly and cheaply, get it out the door, receive payment, and hope cheap materials, crappy hinges, sloppy tolerances and loose joints won’t matter because, with an intended useful lifespan of 200 years, Poor Quality Equals Failure.
In my experienced professional opinion the only effective way to ensure quality is to actively plan for it during the design phase. It would be foolishly optimistic to imagine quality could be achieved otherwise.
This is one area where the pooch walked funny for a few days because I screwed it good. But wait, there’s more to this tale of shame. When I realized my mistake and tried to remediate it, I only compounded it. Poor sore Poochie!
You, Gentle Reader, have of course never suffered this sort of humiliation, but in the interest of sad and abused toolchests everywhere, I bow my shiny bald head, place my hand over my heart (it’s rattling around here in my chest somewhere, although my wife sometimes disagrees) and humbly confess all. One or two teardrops fall, …
When new, my toolchest was striking in appearance, with highly figured solid mahogany wood panels (not veneer) exposed on the lid surfaces and a clear, high-gloss, rubbed-out catalyzed varnish finish. It was a thing of beauty, but not a joy forever because, after several years of use in a drafty, dusty, pixie-infested garage shop followed by several long-distance moves and more than a few months of exposure to wind and sun it was scratched, dinged and crazed.
In my foolish vanity I repaired it using what I thought were sound techniques and quality materials, but which eventually proved to be wasteful.
I’m a highly-edumacated fella, you know, and during my studies at the University of Stupid, School of Hard Knocks where I earned an MD degree (Master Dipstick, Summa Cum Laude) I learned that catalyzed varnish was not tough enough. Out of an abundance of humility I don’t display my UoS graduation certificate on my “I Love Me Wall,” so please don’t ask to see it.
Drawing upon my training at UoS, I next refinished the toolchest with a brushed-on spar-varnish finish. Not as pretty, but it was more flexible and more resistant to scratches and UV rays. But ultimately, it too failed. Poochie wept!
As the wise Nigerian Prince Musa Adebayo once told me (in exchange for a small wire transfer to his bank in Abuja, of course), “ Time destroys all things.” This eternal truth definitely applies to woodwork finishes, but I didn’t realize at the time he was talking about credit ratings!
A decade or so later the toolchest (aka “Moby Dick”) was as scratched and gouged on the outside as its fishy namesake such that no translucent finish could conceal the repairs, forcing me to seek a more practical solution, one that would spare poor Poochie further indignity.
On that bright day I said to myself: “Self,” (of course, I don’t address myself as “Mr. Covington” when deliberating with myself, because that would be insane), “Would you wear a bespoke tuxedo with handmade alligator skin dress-shoes to a muddy jobsite to perform a foundation rebar inspection?” I had to think about it for a while because, as you know, fashion is my life, but with a sigh of resignation I eventually answered myself, because that’s the only polite thing to do. The response was a resounding “No.”
In my supervisory role, I’m obligated to perform periodic construction jobsite inspections as part of quality control measures to ensure compliance with plans and regulations, but I wouldn’t wear a black tuxedo and delicate loafers to a jobsite any more than I would wear board-shorts and flip-flops. Instead I dress in tougher clothes that protect my legs and don’t instantly tear if they get hung-up on a rebar cage, and that won’t look filthy if they get a little muddy. And when the paparazzi’s cameras aren’t rolling (they seem to follow me everywhere, donchano (ツ)) I prefer boots that actually protect the tasteful glitter-varnish finish that decorates my fuzzy pink toes.
With greater age and experience I finally concluded that in my vanity I had erred by trying to make a toolbox look like pretty furniture. Feel free to mock the fool if so inclined but no tossing of rotten eggs, please!
So, determined to not make the same mistake a third time, I researched finishes that might work. In the end I rejected the extremely tough, expensive and difficult-to-repair industrial solutions such as Imron and Polane and settled on a cheaper, friendlier and easier-to-repair solution; I sanded my toolchest down to bare wood and refinished the exterior with distressed milkpaint per Mr. Dunbar’s recommendations, as discussed in a previous post, and shellac on the inside.
When cured, milkpaint contains oodles of hard mineral solids with few volatiles to evaporate over the years to cause shrinkage and cracking (unless you want it to craze). It is not as flexible as latex paint but much tougher long-term than any clear finish. UV protection is absolute.
Like a Tabasco Sauce stain on camo pants, repairs are nearly invisible, indeed they even improve the chest’s character. With a bit of primer, milkpaint covers bondo used to repair the cuts, scratches, and dings incurred during international moves, the ravages of rabid forklift attacks, and even injuries received from the slings and arrows of outrageous fortune (yes, here at C&S Tools we quote literary giants such as Shakespeare andRed Green). Latex paint works too, but milkpaint looks better and it’s far tougher.
But Gentle Reader, you are no doubt wondering what all this rambling has to do with “repairability.” The point is that repairs to a distressed milkpaint finish are easily accomplished and don’t look like repairs even when made to localized spots, they just give the overall finish more “character” making it look more interesting. No other finish I am aware of looks better with age and wear. Now that’s true repairability.
I only regret it took so long to stumble upon this excellent solution. So does Poochie.
Mechanical Repairability: Hinges & Screws
Hinges always wear out. The historical record shows that cute iron hinges secured with small steel screws, while inexpensive and “historically correct,” always fail, usually sooner than later, as Murphy dictates. And when they fail, Murphy also ensures that they cause interference and secondary damage.
Would you use flimsy sheet-metal cabinet hinges to secure the tailgate of your pickup truck knowing that one day you may see that same tailgate in your rear-view mirror scattering festive sparks as it skates down the highway behind you? Why would you put them on your toolchest?
Being in the construction industry I know the solution to hinge durability is to use more, bigger, corrosion-proof hinges because larger internal bearing/wear surfaces free of abrasive iron oxide wear slower and keep things tighter. Think stainless-steel or brass door hinges. Commercial ball bearing door hinges are good too, but the bearings are oriented for an axial load, not a side load, so the cost-benefit analysis of bearings in this application is weak.
But I digress. How does one plan for repairability in the case of hinges? The answer is simple: “R&R,” as in “remove and replace.” Let’s look at “replacement” first.
Unless you or your descendants (assuming the chest stays in the family, which it should) intend to have replacement hinges custom-made when the original set wears out (funded by the generous cash inheritance you will no doubt bequeath them) I recommend you plan for the original hinges to be quality products matching industry-standard specifications. Why would you use custom-forged hinges that look “antiquey” but that aren’t a standard dimension for which replacements are easily purchased? A toolchest is not a jewelry box.
I recommend you use door hinges in standard sizes so they can be easily replaced without hiring a blacksmith when the time comes, a day that certainly will not fall within your lifetime if you heed the advice in the previous paragraphs. This is the essence of “repairability” as it applies to hinges, IMO.
Moving on to the “remove” aspect of R&R, what else can go wrong with hinges? That’s right, those pesky screws.
If you use the skinny, short screws that are packaged with the hinges, sure as eggses is eggses they will begin to dance the reverse macarena after a decade or four. I promise you that when that inevitable day comes, replacing them and their worn-out holes will be a pain in the shorts. And what happens to the wobbly lid before you or your great grandkids get around to fixing those idiot screws?
But wait, it gets worse (stay away Poochie, stay far away!). What happens when the hinges wear-out or fail but you can’t remove the blasted screws to replace them because they have broken-off in the screwhole during the removal attempt? That’s right, blasphemies and curses will fly because a clean replacement will be difficult, and perhaps never happen, turning a measly two-hinge chest into a lop-sided one-hinge chest. Why would you give Murphy the satisfaction?
The best way to improve the “remove” factor in R&R therefore is to use oversized, extra-long, stainless steel grade 8 screws actually made in American, Europe, or Japan. Oversized because strength improves durability. Extra-long because the deeper a strong screw is embedded in the wood, the more resistant to the reverse macarena it will be.
Grade 8 because this is an industrial specification that tells you something about the screw’s quality, reducing doubt. They cost more, but are worth it when you consider what would happen if a cheaper screw, one made to no quality specifications, breaks off in the hole when it comes time to remove/replace it.
Stainless steel because brass is too weak and a rusty carbon-steel screw will become a loose screw every frickin time.
Made in America, Europe or Japan because, while Chinese-made screws are cheap (often sold under false pretenses as “quality fasteners”) one must assume they are ALWAYS defective and will SURELY break. Indeed, it’s not a matter of “ if” they’ll break but only “when.“ Murphy won’t need to lift a finger.
If an inexpensive stainless-steel screw is sold at a big-box retailer, even if it’s represented to be Grade 8, assume it’s made by Godless, bait-n-switch commies. No, not the gangsters that burned down Portland, Seattle and Minneapolis, nor the ones that govern the coastal strip of land between Mexico and Oregon, but those in Beijing.
Reputable marine supply stores may be the best source for quality stainless steel screws.
I also encourage you to prep the screw holes in the hinge plates by countersinking them to the right depth and angle for solid, maximum contact between screwheads and plates.
Prep the screw holes in the wood too. Drill pilot holes the right size and right depth, and put epoxy or glue in the holes just before inserting the screws to penetrate the wood and reinforce the threads the screws cut into the wood.
And if a screw becomes loose, figure out why and repair it instead of just screwing it in tighter and tighter until it strips out.
Remember: History always calls an optimist who didn’t prepare for the worst eventuality a bone-headed loser.
Mechanical Repairs: Tray Sliding Surfaces
Besides hinges the other things in a toolchest that always wear out and need repair are the surfaces that support the trays and on which they slide. This normal wear is easily remedied by planing the old, worn surfaces flat and gluing in durable hardwood wear strips. The lower the coefficient of friction the better. I have installed six replacement sliding surfaces to the ledges of my toolchest. In retrospect, it would have been better to rabbet and glue these strips in-place when new so they would be easier to remove & replace when necessary.
Knowing these surfaces would wear and need replacement, I intentionally screwed the ledges that support the trays to the chest’s sides so they can be removed and easily worked on with handplanes instead of gluing/doweling them in-place. I highly recommend this design detail.
The subject of “reversible adhesives” such as hide glue or starch glue is interesting, and relevant to repairability because such adhesives make non-destructive disassembly of wood joints possible. Unfortunately I have no experience with hide glue.
A renowned master joiner taught me his philosophy on the subject of glue, and it has stuck with me (pun intended). He held that it’s the craftsman’s job to make his work as precise and durable as possible when new, therefore obligating him to use the strongest, most durable glue available to him and reasonably practicable to ensure that, if repairs are necessary, it won’t be because the glue failed.
He learned the trade when the only available woodworking adhesives were “nikawa” hide glue, or starch glues made from rice, so he knew all about reversible adhesives. But when I knew him, he used PVA glue.
When I once mentioned I had read that rice glue should be used for fine joinery work to make repairs easier, he looked at me like there was a wriggling frog’s leg hanging out of my mouth, and turned away in disgust. Nuff said.
Thank you for reading this series of posts about toolchests. I hope you found it interesting, or at least amusing.
I would like to conclude with a Japanese saying relevant to the subject of this article: 「石橋を叩いて渡る」pronounced “ishibash wo tataite, wataru.” A direct translation of this idiom is “Strike a stone bridge before crossing,” meaning to “take every precaution.” I have a similar saying that goes “Belt, suspenders, safety harness.” I encourage Gentle Readers to consider this principle when designing and constructing toolchests for their personal use.
If you have questions or would like to learn more about our tools, please use the questions form located immediately below. Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google, incompetent facebook, or twitchy Twitter and so won’t sell, share, or profitably “misplace” your information. May my grandchildren become lawyers if I lie.
I am past scorching; not easily can’st thou scorch a scar.”
Herman Melville, Moby-Dick or, the Whale
We have presented 15 varieties of Japanese chisels for your consideration at this blog to-date. In this post we will examine a specialized version of the Atsunomi previously presented in Part 8 of this series, made from high-speed steel.
The C&S Tools High-speed Steel Atsunomi
The chisel in question is made by Mr. Usui Yoshio of Yoita-cho, Nagaoka City, Niigata Prefecture, under his brand name of Sukemaru. The shape of this tool is identical to his standard atsunomi, the only significant differences being the type of steel used and the bright appearance of the blade. This is not a small chisel but a professional-grade, rugged tool with an overall length of approximately 300mm (12″). It is an indispensable tool in some situations.
If you need a smaller, handier, and more economical HSS chisel, please take a look at our HSS Oiirenomi also by Sukemaru.
What is High-speed Steel?
So just what is high-speed steel (HSS)?
HSS is a tool steel developed for manufacturing commercial cutters, dies, etc. In this case, Usui-san uses a high-speed steel designated SKH51 in Japan, the equivalent to M2 in the USA, BM2 in the UK, HS6-5-2 in Germany, and Z85WDCV06-05-04-02 in France. This is the most popular HSS in the world. If you own router bits without carbide cutters, and not made in China, you own this steel.
This variety of HSS contains buckets-full of tungsten, molybdenum, chrome, with a stout vanadium chaser.
After oven heat-treat, these chemicals make the steel tougher, more abrasion-resistant, and more resistant to softening (aka “temper-loss”) when subjected to high-temperatures than regular high-carbon steel. Its nickname of high-speed steel comes from the tendency of cutters made from this steel to retain their hardness even when worked so hard blade temperatures become hot enough to draw the temper of standard steel cutters, softening and making them useless.
The chemical composition is listed below, just in case you are interested. You can see what I mean about “buckets.”
Chemical composition of SKH51/M2 HSS Steel
Why Use High-speed Steel?
The next question in our Gentle Reader’s minds, no doubt, is “what are the properties of high-speed steel and what difficulties can a chisel made from this special steel help me overcome?” Let’s answer these questions below.
Toughness and Shock Resistance
Perhaps the most significant property of high-speed steel is its toughness. SKH51 (M2) steel is the most shock-resistant of the high-speed steels, making it especially suitable for use in a chisel that may impact hard objects in daily use but must survive without chipping or breaking. This toughness provides huge benefits in the situations described further below.
Abrasion resistance goes hand-in-hand with toughness, but it is a different characteristic many misunderstand. It does not mean a cutting edge will be sharper than a cutter made of high-carbon steel, only that it won’t wear and become dramatically rounded-over as quickly. In the case of chisels, a blade made from highly abrasion-resistant tool steel will reach a certain level of sharpness (or dullness) and remain at that level a relatively long time allowing a cutter to keep on cutting without becoming useless. But the quality of the cut will decrease, and energy necessary to motivate the blade will of course increase as the blade dulls with use.
Abrasion resistance is not typically considered overly important in blades where great sharpness is given priority, but it is extremely important when the blade is used to cut materials such as exotic hardwoods that contain silica crystals, or Engineered Wood Products that contain hard adhesives and/or highly-abrasive particles such as silicon carbide deposited by sandpaper, or dirty wood contaminated with sand, grit and other contaminants that will literally destroy the cutting edge of a plain high-carbon steel blade making it useless.
Just as a strong truck would be at a hopeless disadvantage in a Formula One race, a McLaren MP4/6 with all its speed, power and agility couldn’t tow a heavy trailer 100 yards through the mountains. Horses for courses.
Engineered Wood Products
One major challenge the HSS atsunomi excels at overcoming is modern wood products called Engineered Wood Products (EWP)
Commercial carpenters and cabinet makers nowadays have no choice but to use modern EWP such as plywood, MDF, HDF, OSB, LVL, glulams, etc.. Unlike new, clean, solid lumber cut with saws and planed with knives to final dimensions, engineered wood products are comprised of wood veneer, chipped wood and/or sawdust glued together by hard adhesives that will harm standard steel tool blades. HSS handles these difficult adhesives easily.
A bigger problem associated with EWP is the extremely hard abrasive particles left embedded in them by the sanding belts used to dimension and smooth them, particles much harder than any heat-treated steel, that will quickly destroy a good high-carbon steel chisel. Being much tougher and more abrasion resistant than high-carbon steel, HSS can handle this abrasive residue without being destroyed. That does not mean abrasive particles do not scratch and dull HSS atsunomi cutting edges, it just means they won’t chip or break and will keep on cutting longer than HC steel blades.
Restoration & Remodeling Work
Another type of work this HSS atsunomi excels at is restoration work, remodeling work, and chisel work around concrete and masonry.
In the case of restoration work, the job usually involves cutting wooden structural members and finish materials that are old and dirty and contain hard abrasive dirt, sand, small stones and of course hidden nails and screws that will not only dull a chisel blade but may badly chip it.
For instance, a Beloved Customer who is a timber-frame carpenter in the Czech Republic was tasked with splicing segments of new timber to replace rotted-out sections of a large number of 300 year-old rafters during the ongoing restoration of the Grand Priory Palace located in Prague (constructed from 1726 to 1731), an ancient city with many beautiful, old structures.
The wood was dirty and full of gravel and broken-off nails that chowed down on standard chisels without pausing for a drop o’ Tabasco Sauce. But our HSS atsunomi chisel made it possible for him to cut and fit the timber splices while working on the steeply-slanted roof far above cobble-stone streets without chipping the blade and without stopping the work for frequent resharpenings beyond an occasional touchup with a belt sander.
In the case of remodeling work, one must routinely cut precise holes through existing wood contaminated with abrasive dirt and hiding screws and nails, as well as lathe, plaster and drywall containing abrasive sand, and in close proximity to mortar and concrete which contains sand and gravel aggregates that will dull, chip and even destroy a standard chisel in two shakes of a lamb’s tail.
If you have ever done remodeling work or an installation that took a chiselwork to perform, you know the despair one feels when gazing upon the damage done to a beloved tool.
Likewise, during installations, cabinetmakers must make precision cuts in abrasive engineered wood products such as plywood, OSB and MDF. Our HSS atsunomi chisel, as well as our HSS oiirenomi chisel excel at this job being far more durable than standard chisels with high-carbon steel blades.
The jigane Usui-san uses for his HSS Atsunomi is a harder version of the standard low-carbon steel he uses for his standard atsunomi. The furniture (katsura (hoop) and kuchigane (ferrule)) are made from mild steel, not stainless steel, despite the bright appearance, and will exhibit corrosion over time. As an option, these two parts can be ordered blackened creating a two-toned chisel some people find attractive.
Heat-treat and Hardness
To prevent chipping, the HSS blade is heat-treated in a special oven in accordance with a formula to a hardness of Rc63, intentionally a little softer than the Rc64 hardness listed for this steel. Even then, this is harder than nearly all currently-available Western chisels we are aware of.
The blade’s bevel angle is 30°, the standard angle for Japanese woodworking chisels. To reduce denting you may want to increase the angle to 35° if you will be cutting through hard materials.
Resharpening in the Field
Another huge advantage of Sukemaru’s HSS chisels is that they can be quickly resharpened to a usable cutting edge in the field using angle grinders and belt sanders without losing temper and softening so long as one is careful to keep temperatures below 650°C (1200°F), not difficult to do if one pays attention. Don’t underestimate the efficiency this feature will bring to your work some days.
The compromise with HSS chisels is that, while they can be made extremely sharp using stones and proper technique, they will never become as sharp as our hand-forged high-carbon steel chisels. Moreover, they will take twice as long to sharpen by hand using conventional wetstones and waterstones. They are not ideal for all jobs.
Sharpening time can be reduced dramatically by using aggressive diamond plates.
We have personally tested these chisels to failure and resharpened them. We are confident of their quality and performance.
If you need an exceptionally tough chisel that can “take a lickin and keep on tickin” even in conditions that would destroy a regular chisel, then the HSS Atsunomi, or where a smaller tool is required, its tough little brother the HSS Oiirenomi, will get the job done for you.
If you would like to know more about these chisels, please drop a note in the form below titled “Contact Us.”
If you have questions or would like to learn more about our tools, please 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, incompetent facebook, or troublesome Twitter and so won’t sell, share, or profitably “misplace” your information. May a thousand bot flies make a home in my eyebrows if I lie.
In this post I would like to introduce a uniquely Japanese tool, a handy and extremely sharp little knife called the Kiridashi Kogatana.
The Kiridashi Kogatana is a handy, general-purpose knife traditionally used by craftsmen in many trades in Japan. It was once a standard tool in every Japanese school child’s school bag for sharpening pencils and carving toys such as taketombo before nanny-state paranoia equated small useful tools in the hands of children with machine-guns operated by mentally-deranged murderers.
Your humble servant won’t presume to speak for others, but it may be that, like me, Gentle Reader frequently needs a sharp knife not just for opening boxes, sharpening pencils and occasionally fending of hordes of snaggle-toothed zombie lawyers (an especially smelly variety of ambulance-chaser), but for serious woodworking tasks such as carving gennou handles, carrying molding details around the inside corners of casework and joinery, carving Buddhist statuary, and whittling toys for children. Despite their revolting table manners, zombie lawyers are easily repulsed with most any garden-variety knife, but for refined woodworking nothing beats a super-sharp kiridashi kogatana knife.
In this post we will examine this traditional and uniquely Japanese tool.
This tool’s name is pronounced kee/ree/dah/shee koh/gah/tah/nah, often shortened to “kiridashi,” and written 切り出し小刀 in Kanji. It translates directly as “small cutout sword.
This simple but sophisticated tool is used, without exception, by all woodworkers in Japan including carpenters, joiners, wood carvers, cabinetmakers, sashimonoshi, bamboo workers, umbrella makers and many other trades.
Gentle Reader may wonder why Japanese professional craftsmen insist on using a tool made from expensive and difficult materials requiring advanced blacksmithing techniques instead of an inexpensive, disposable, Chinese-made utility knife. The short answer is that they have strict performance criteria that tool-shaped landfill-stuffing simply can’t satisfy. Let’s examine some of those criteria, shall we?
One characteristic a useful woodworking knife needs is rigidity without bulk. Flexible, floppy blades cannot easily be directed by our minds. Thick blades are rigid, but are clumsy and a pain to sharpen. Utility knives are especially hopeless in this regard, having floppy blades, fat handles, not to mention garbage steel.
Another important characteristic needed in a woodworking knife is the ability to get one’s fingers close to the cutting edge and point without having them fall off… fingers fall off, that is; You need your fingers.
In the case of the kiridashi, while it lacks a long cutting edge for slicing and dicing veggies, it also lacks a long cutting edge that would prevent the craftsman from choking up on the knife to maximize control. That’s because it’s a woodworking knife, not a kitchen or skinning knife.
The kiridashi lacks the fancy handles that are so popular nowadays. Handles look cool and may feel comfortable when making a cob salad, but are bulky and get in the way when woodworking, preventing the craftsman from getting his fingers close to the cutting edge for maximum control. I don’t know about you, Gentle Reader, but as for your humble servant and thousands of Japanese craftsmen, we prefer to spend money on an excellent blade without a handle rather than a bulky, pretty handle with a sucky blade attached.
But of all the performance criteria the professional woodworker needs to consider when evaluating a woodworking knife, absolute sharpness is the most important, followed by ease of sharpening, two things at which the kiridashi is superior to every other small knife or cutter ever invented.
If you suppose your humble servant is exaggerating, remember that I have used kiridashi to shape wood for 40+ years, and at times they were critical to feeding the wife and babies. Of course, sharpness ultimately depends on the quality of the knife’s blade, and the skills of the sharpener but the fact that the kiridashi can be made sharper quicker than any other woodworking knife ever made is a big advantage for those who need a sharp blade for their work.
Let’s next examine those troublesome materials and blacksmithing techniques and consider what benefits they provide to the woodworker.
Materials & Forge-welded Lamination
I will begin with an explanation of the materials and techniques involved in making the traditional hand-forged kiridashi. We will look at cheap consumer-grade kiridashi in a separate section below.
Quality kiridashi are made using a traditional blacksmithing technique called “forge-welding” to laminate a layer of high-carbon steel called “Hagane” in Japan (mostly either Hitachi Yasuki Shirogami No.1, Aogami No.1, or Swedish Steel Asaab SK120) to an iron or low/no-carbon iron body called “Jigane” similar to that used for blades of Japanese planes, chisels, scythes, and even many styles of traditional kitchen knives. C&S Tools’ kiridashi are hand-forged in the traditional manner to maximize performance as required by our Beloved Customers that work wood professionally.
Inexpensive kiridashi knives are made from SK steel, another variety of Japanese high-carbon steel but of lower purity used for many commercial and agricultural products. This is an inexpensive and useful tool steel, but due to the additional impurities it contains, unavoidably produces an inferior-quality crystalline structure negatively impacting cutting and edge-retention performance.
Because kiridashi kogatana are relatively narrow, thin knives, Aogami steel is often preferred by blacksmiths over Shirogami or Swedish Steel because it tends to warp and crack less during heat treatment yielding fewer rejects.
C&S Tools’ kiridashi are made from either Shirogami No.1 or Swedish Steel.
We will briefly examine why this lamination is necessary below, or for more details, please read the longer articles on this subject linked to above and below.
The Hollow-ground Ura
Most kiridashi kogatana have a hollow-ground Ura, just like Japanese chisel and plane blades. The advantage of the Ura is that it makes it easy to quickly sharpen the exceptionally hard steel that forms the blade’s cutting edge. There are always inexperienced people who mistakenly imagine the ura is unnecessary, so allow me to clarify why it is critical.
To begin with, the layer of cutting steel in the kiridashi, or at least C&S Tools’ kiridashi, is hardened to Rc65~66, substantially harder than woodworking blades in the West. This hardness, combined with the excellent crystalline structure made possible through proper hand-forging and heat-treating by an experienced blacksmith produces a blade that meets the following essential requirements of a professional woodworking tool:
The cutting edge can be made extremely sharp;
The cutting edge will stay sharp a relatively long time;
The cutting edge won’t easily chip, crumble, roll or break; and
The knife is easily and quickly sharpened.
Items 1~3 above are normally satisfied when an experienced blacksmith skillfully forges and properly heat-treats high-quality high-carbon steel, but because the steel in the finished product is so hard, satisfying the fourth criteria becomes difficult without some innovation.
The conundrum the blacksmith must resolve is that, in accordance with materials science, given a fixed area of steel (measured in square millimeters, for instance), the harder the steel is, the harder it will be to sharpen. The solution is to hollow-grind the steel lamination reducing the square millimeters of hard steel that must be abraded thereby reducing the time, elbow grease and sharpening stone mud expended in maintaining the blade.
Another problem one faces when trying to sharpen a large area of flat hard steel is that the perimeter of the flat area always wears faster than the center, eventually resulting in a high spot at the center of what was once a flat area. This too is a fact some inexperienced folk dispute; We wish them many joyful hours popping their bubble wrap.
This unintentional high spot matters because it makes it more difficult to keep the flat at the cutting edge in tight contact with the sharpening stone, which in turn makes it more difficult to cleanly and quickly polish away the burr. Clearly the flat side of the blade needs to be truly flat if we are to quickly and consistently achieve a sharp edge.
The solution to these two problems is to create a hollow-ground area at what would be the flat on a chisel, called the “Ura.” We will dig into the details of this feature below.
And finally, since it would be time consuming and financially inefficient to abrade a bevel of uniformly hardened steel, the lamination replaces most of the hard steel exposed at the bevel with soft, easily abraded iron.
Despite this knife’s simple appearance, it’s a very clever and sophisticated design.
Pre-laminated Steel & Mass Production
Except for those sold by C&S Tools, most kiridashi kogatana sold nowadays are made from pre-laminated steel called “rikizai,” (利機材) or “fukugozai” (複合材) a material invented for mass-producing consumer-grade kitchen knives inexpensively and in high-volume. Dies and presses in factories are used to cut blanks from strips and sheets of this steel which are then ground and sanded by automatic machines and heat-treated in large lots in ovens. The result is a knife that is cheap to produce (despite the high price often charged to unaware consumers) and quite useable, but since the blade has not been forged through multiple heats, or been normalized and subjected to multiple quenches, the crystalline structure of the cutting edge is inferior such that the knife cannot be made as sharp, it will dull quicker, and may be harder to sharpen. Such kiridashi kogatana also tend to be thinner, like kitchen knives, and are not as comfortable in the hand for hard work over long hours.
We prefer the performance and ease of use of hand-forged traditional kiridashi, so this is the only type we sell. Along with most professional woodworkers in Japan, we feel they are worth the extra cost. But if you decide to try a cheaper mass-produced kiridashi, please be careful you are not sold a pimped-out mass-produced blade at the price of a more labor-intensive, skill-intensive hand-forged traditional knife. Caveat emptor baby.
Right & Left
Kiridashi kogatana come in right-hand and left-hand configurations, with the right-hand variety being most common. To differentiate a right-handed knife from a left-handed one simply hold the knife with the cutting edge facing downward. The bevel of a right-handed knife will be on the right side as seen from above.
Craftsmen in many trades, especially cabinetmakers, shashimonoshi, joiners and woodcarvers will often own both left and right-hand versions because the type of work they do requires a different bevel orientation for some jobs particularly when shaving wood contrary to the grain, for example when shaping the inside corners of curved wooden components.
Blade Width & Thickness
The width and thickness of the blade and the angle of the cutting edge to the centerline of the blade are matters of individual preference. Generally speaking, a wider blade is easier to grip than a narrower blade, and is also easier to power through cuts. On the other hand, if too wide, it will feel clumsy in the hand and may not fit into tight spaces as well.
Likewise a thicker blade is easier to grip and easier on the hand when making high-pressure cuts for long periods of time than a thin blade. On the other hand, a thicker, wider blade weighs more and may take longer to sharpen.
It’s worth figuring out which style works best for you.
The angle of the cutting edge (not the bevel angle) is easily adjusted to personal preference within limits. In general, a steep angle forming a relatively oblique tip is better suited to making deep, powerful cuts, while a shallower angle provides a more slender, pointer tip that is preferred by many for finer cuts, especially long diagonal slices, in narrow spaces.
The downside to the slender pointy knife is that the point tends to be more fragile, and is more difficult to sharpen.
Despite its simple appearance, the kiridashi kogatana is a sophisticated and unusually effective knife. There are, however, many examples of kiridashi with artistic and even anthropomorphic shapes such as vegetables, and even fish in the knife pictured at the top and end of this article.
Handles and Scabbards
Some people prefer a kiridashi with a handle of sorts, although most professional craftsmen, in our experience, prefer the bare metal.
A wise craftsman will have some means to protect the blade from becoming damaged when not in use, and to protect other tools and fingers from its frightfully-sharp cutting edge. A no-cost, thin scabbard or sheath can easily be made from cardboard or plastic, but the wooden combination handle/scabbard pictured above is a clever solution taught to me many years ago by a master joiner of great renown.
In a future post we will discuss how to make a convenient combination handle and scabbard for the kiridashi kogatana.
Why Should You Use a Kiridashi Kogatana?
I can’t tell you why you need a kiridashi, but I can tell you why I and many others use them. Perhaps some of these reasons apply to you.
One can get by with disposable-blade utility knives for low-quality and rough work such as opening boxes, cutting gypboard, or discouraging icky deadish members of the legal profession, but such knives are not up to most serious woodworking jobs for several reasons.
First, while utility knives are sometimes called razor knives and may even use razor blades for cutting edges, they are nowhere near as sharp as a good kiridashi. The fact is that surgical scalpels are not as sharp as a good kiridashi sharpened by someone with skill. And utility knives dull quickly because the steel is soft and of miserable quality. You’ve not doubt noticed this poor performance.
Second, while your approach to life may be different, in my decrepitude I have come to despise stuffing landfills with throw-away tools, especially those made in the increasingly-despotic and bloody-handed kingdom of China. It doesn’t make sense environmentally or morally. I prefer a faithful, high-quality kiridashi knife that can easily be made sharper than any commercial razor and will serve faithfully for decades without complaining.
Third, a good kiridashi is a compact tool with a stiff blade to which one can apply heavy pressure for serious cutting, and a single-bevel that provides exceptional control for detailed carving and trimming tasks. It’s a tool that becomes an extension of my mind when it is in my hand. Can’t do any of that with a flimsy, clumsy utility knife.
And finally, while conventional double beveled knives are useful, because they lack the lamination of fine-grained exceptionally hard steel and the clever ura, they take longer to make as sharp as a good kiridashi and dull quicker.
As they say in Japan: “The difference between the moon and a mud turtle.”
If you use knives in your work and you need them to be literally sharper than a razor and stay that way a long time without spending tons of time and attention, then nothing beats a good hand-forged kiridashi kogatana knife. All those generations of Japanese craftsmen can’t be wrong.
If you have questions or would like to learn more about our tools, please 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, incompetent facebook, or sneaky Twitter and so won’t sell, share, or profitably “misplace” your information. May my nose fall off if I lie.