The Marking Knife

A spearpoint marking knife

“Make sure that you always have the right tools for the job. It’s no use trying to eat a steak with a teaspoon and a straw.” 

Anthony T. Hincks

There are many varieties of marking knives used for woodworking around the world. In this article your humble servant would like to discuss the Japanese version.

We will begin with some definitions, followed by an explanation of the design details and structure of the tool. We will save the best for last by describing two subtle but effective professional modifications to improve the tool’s performance and the results produced.

Definitions

The Japanese marking knife is called a “shiragaki” or sometimes “shirabiki.” The characters used vary, but can mean “white pull” (白引き), which makes some sense, or “white persimmon” (白柿), which makes little sense, so I suppose the persimmon character is used as a phonetic substitute for “kaki” (書き) which means to write. I choose to write the word as 白書 so the Kanji translate directly to “white writing.” That makes more sense to me.

Such confusing substitutions are all too common in the Japanese language in the case of words with purely phonetic origins. The fact is that, much like psychologists, lawyers, and priests, the Japanese people enjoy confusing terminology. It’s an ancient habit that probably won’t change soon. I say this as someone that has been reading, writing and speaking the Japanese language at graduate school level for 45 years, been a resident of, attended school and worked in Japan for 30 years, and been married to a Japanese woman and had Japanese relatives for 43 years. I can get into serious trouble in the Japanese language.

Now that we are done with the Japanese language lesson, I will simply call this tool a “marking knife.”

The marking knife is used to cut thin, precise layout lines in a board’s surface, most often but not always at a 90 ° angle to the direction of the wood grain.

Every woodworking tradition I am aware of includes the marking knife, and regardless of their preferred style, anyone serious about woodworking will own at least one, and know how to use it.

Advantages

The marking knife has some advantages over other methods of marking a line more-or-less perpendicular to the direction of the wood grain. Here are a few:

  1. The line it makes can be as thin as the edge of nothing, achieving precision unapproachable by pencils, pens, scribes, sumisashi, inklines, chalklines, laser-sights, or even wishful thinking for layout in wood in the case of lines at more-or-less 90˚ to the direction of the grain. The line it makes, however, is not as easy to see as an ink or even pencil line, so it is not always useful for rough layout work;
  2. The line cut by a marking knife penetrates the wood’s surface providing a physical place into which the woodworker can index the edge of his chisel, or nicker of his plow plane or rabbet plane, or the teeth of his saw, or points of his divider quickly, precisely and confidently without relying heavily on Mark-1 Eyeball, improving the efficiency and quality of both his layout and fabrication efforts. The resulting time savings, improvement in accuracy, and reduction of eye strain the indexing benefits marking knife lines provide are huge.
  3. When making layout lines on perpendicular faces of a member, such as a table apron, for instance, after making one line on the reference face, the remaining three lines can be indexed and extended from each other with a marking knife, confirming the accuracy of the member’s dimensions and ensuring the tenon shoulders will be sawed accurately creating an excellent tenon, assuming the craftsman knows how to use a saw properly, of course.
  4. The line cut by a marking knife severs the fibers near the board’s surface helping to prevent fibers from being torn out of the wood avoiding a ragged cut with saw, chisel or router.

Are you convinced yet?

Design & Materials

Shirabiki Ura by Konobu

There are many styles of marking knives used around the world, and your humble servant has tried most of them at one time or another, but none that I am aware of are as simple as, or functionally superior to, the Japanese version.

Lacking a pretty, turned handle and looking more like a blackened steel popsicle stick than a finished tool, the Japanese marking knife appears unfinished, even barbaric. But despite its stark appearance, it’s a sophisticated design that employs superior metallurgical and blacksmithing techniques.

Like many Japanese woodworking tools, the professional-grade marking knife is made with a layer of hard high-carbon steel forming the cutting edge, forge-welded to a softer layer of low-carbon steel which forms the body of the tool. They are almost always flat, generally thin, and not especially wide tools. Perhaps 1/2 the length of one side is ground flat and bright and includes a hollow-ground depression called the “ura,” while the other side is plain and includes the cutting edge’s bevel.

Some marking knives, such as the photo at the top of this article, have a spear point or “kensaki” (剣先)meaning “sword point” which is convenient because the same knife can be used either left-handed or right-handed. Some people prefer this style, but in my experience it has limited usefulness. To each his own.

The demands on the marking knife in terms of sharpness, durability, and edge-holding capability are not as high as for chisel and plane blades. The better-quality ones are hand-forged of high-carbon steel and quality jigane, properly shaped and filed, and carefully heat-treated.

Because of their thinness, marking knives tend to warp badly during heat treat, and consequently demand either a blacksmith with good skills or the use of high-alloy steels that warp little. Even experienced blacksmiths end up with a few rejects due to cracking and excess warpage, which perhaps explains the relatively high cost of handmade ones. It has mostly been a tool made by specialist blacksmiths.

For this reason, and because the performance demands on the cutting edge are not severe, Blue Label steel is entirely acceptable IMO.

The Ura

I mentioned the “ura” above, but let’s examine it a bit more. Ura is a Japanese word written using the Chinese character  浦. It means a bay or inlet from a lake or ocean, usually without lots of rocks, and often with a sandy or gravelly shore. You can imagine why this word was employed to describe the hollow-ground depression in many Japanese woodworking blades.

In North America, similar curved surfaces and depressions were once called “swamps” even though they were made in metal. This term is obsolete nowadays.

The ura is what makes the Japanese marking knife superior to its Western counterparts for two reasons. The first reason is that the ura makes it easier to keep the hard layer of steel at the reference side flat. Second, in light of the hardness of the cutting edge layer, the ura makes it easier to sharpen the cutting edge.

Without the ura, the hard steel would be time consuming to sharpen and would tend to become rounded instead of remaining a flat reference face to index against a steel square or straightedge. It’s a subtle and clever design more sophisticated than its simple appearance suggests.

In use, the flat ura side is pressed lightly against the leg of a steel square with the point cutting lightly into the wood and the heel floating above. The blade is then pulled toward the user to cut the straight layout line.

Lubrication

I recommend Beloved Customer use an oilpot to lubricate the marking knife’s blade to reduce friction and wear between the blade and the square, as well as friction between the cutting point and the wood. Not only will  your square last longer, but your layout lines will be more accurate. Don’t believe me? Give it a try.

Recommended Modifications

Marking knives are simple tools for a simple job, but there are a couple of subtle improvements some advanced Japanese craftsmen, especially joiners, make that Beloved Customer may want to consider.

1. Habiki

The first improvement is intended to minimize one downside of the marking knife, namely its habit of shaving metal from the square or straightedge used to guide it. In Japanese this modification is called ” habiki “ 刃引き which translates directly to “ blade pulling, ” as in pulling the blade’s cutting edge over a stone to intentionally dull it. It is a term borrowed from the sword world.

The steps to accomplish this modification are as follows:

  1. First, sharpen the blade;
  2. Then, with the tool’s ura side facing you, stand the blade vertically on its cutting edge on the face of a medium grit waterstone or oilstone with the last 2~3 millimeters of the blade, measured from the tip, hanging off the stone’s side so the tip does not contact the stone;
  3. Finally, drag the blade towards you creating a flat on the cutting edge, while leaving 2~3mm of the blade’s tip sharp. Voila.

The dulled portion of the cutting edge will now be less likely to shave your square or straightedge, while the sharp tip will cut the wood and make a pretty, accurate layout line, assuming you do your job, of course.

I know that the idea of sharpening a good blade and then intentionally dulling part of the cutting edge sounds gaga. In fact, when Honda-san showed it to me, I thought the old guy was pulling my leg. But Honda-san was a master among masters, a man in his 80’s who had been making extremely high-end custom joinery since he was 15 years old, one who took his tools extremely seriously. In addition, he let me try his knife so I was quickly convinced.

Honda-san’s technique works, so gather up your courage and give it a try before allowing your inner-troll to embarrass you. I promise you’ll like the results and your square will thank you.

2. Tip Bevel

The second modification is also one Honda-san taught me. There are several ways of doing it, but the essence is to grind an angled flat 15~18mm long  on the top edge of the blade’s side angled away from the ura, ending at the cutting edge’s point. The goal is to create a very sharp “clipped” point.

This angled flat has three purposes: First, it removes metal that would otherwise get in the way of your clearly seeing the knife’s cutting tip. This is important because often a knife must be indexed off a tiny divider point’s mark or a previous layout line, for instance when marking the shoulders of a tenon on four sides of a stick of wood. Removing this unnecessary metal will make it easier to begin the mark exactly where it is needed.

The second purpose is to reduce the friction between blade and wood when cutting a layout line, thereby improving control like racing tires on a fast car.

And third, it provides a convenient place to rest your fingertip to better control the knife.

If you imagine this modification can’t make much of a difference, then your lack of experience is showing. How embarrassing >~(ツ)~<

The Square

I know there are those who prefer to use a wooden square for layout work, and others who like brass ones. Both work just fine with a marking knife until they don’t. You would be wise to consider using a hardened steel square, or better yet, a precision hardened stainless steel square with your Japanese marking knife; They simply last longer and stay straighter.

There are hardened carbon steel and hardened stainless steel combination squares and die maker squares available on the market, but I think they are too bulky and too costly for making simple 90° layout lines on wood.

Matsui Precision produces a series of excellent hardened stainless steel squares that are popular in Japan and well worth the cost. I have been using them for years. Send me a note if you are interested.

The Japanese marking knife is a great tool. Once you use one, especially after making the modifications described herein, you will wonder how you ever got decent layout work done before.

YMHOS

My old marking knife was hard on my eyes and fingers, but now I know how to fix it!

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. May my square always lie to me if I lie to you.


The Forgotten Sumitsubo 忘れ物の墨壺

The Forgotten Sumitsubo

Remember me when I am gone away,
Gone far away into the silent land;
When you can no more hold me by the hand,
Nor I half turn to go yet turning stay …

Christina Rossetti

The tool pictured above is a very old “split-tail” variety of “sumitsubo.”

Versions of this tool are used in many trades worldwide to mark a straight layout line on material being worked. In the West, the line is coated in chalk to produce a “chalkline” when snapped, but in Japan a silk line wound on the spool near the tail of the tool is soaked in ink as it passes through the “pond” near the pointy front of the tool to produce the same sort of layout line.

This particular tool is unusual not only because it is one of the best-preserved examples of sumitsubo in existence, but also because it was discovered during restoration work on the 27m tall Nandaimon gate of Todaiji temple in Nara Japan in 1879.

Since its discovery it has become famous as the so-called “Forgotten Sumitsubo.”

The reason for the unusual name, indeed the very reason it has survived in such a good state of preservation, is that Todaiji Temple’s Nandaimon gatehouse where this sumitsubo was found perched peacefully on top of a beam high in the structure was built in the year 1199, so it is likely this sumitsubo had remained there undisturbed for around 680 years, a long time for a wooden tool.

Was it really forgotten? I like to think some carpenter left it there on purpose to look after his work. But that’s just me…

Related image
Front elevation of the Nandaimon gate of Todaiji temple, Nara, Japan. The deer of Nara are like pigeons. The stall to the left is selling “deer crackers” for tourists to feed them.
The eaves of Nandaimon Gate
Related image
Looking up into the structure of Todaiji’s Nandaimon Gatehouse
Cross-section sketch of Todaiji’s Nadaimon Gate

So, if you ever misplace a tool at a jobsite, instead of fretting about it, just imagine that someone, someday, will find it hidden inside the building 700 years later and reverently put it in a museum. Certainly more romantic than any other more likely option. (ツ)

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 the two guardian kings above refuse to let me shower alone.

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The Japanese Sumitsubo Inkpot 墨壺: Part 1

If your wife’s having a good time and you’re not, you’re still having a better time than if you’re having a good time and she’s not.

Red Green

The sumitsubo is a Japanese marking and layout tool similar in function to the Western chalk line. Although few Gentle Readers in Western countries have experience using this tool, it has much to recommend it.

In this post we will briefly examine this tool so prevalent in Asia. Our focus however, will be on the traditional wooden versions, not the modern plastic one, a version of less beauty but perhaps more utility

Sumitsubo is written using the Chinese characters 墨壷 which directly translates to “ink pot”  and pronounced “sue/me/tsu/bow.”

The inkpot has been a common tool in many Asian countries since ancient times. Indeed, until recently, few craftsmen in Asia had even heard of the dusty chalkbox used in the West.

This is just conjecture by your humble servant, but the fact that nearly all writing and much artwork in many Asian countries during recorded history relied heavily on brushes and sumi ink, the black carbon reside of burnt pine sap, may be the reason the inkpot became the standard tool for marking straight (and sometimes intentionally curved) lines.

Using the Sumitsubo

The sumitsubo works on various surfaces including wood, stone, concrete, gypsum board, and other construction materials. It is not unique to Japan, but is found in one form or another throughout Asia. It is an essential tool for carpenters.

A thin line spooled around a reel attached to the sumitsubo passes through holes at each end of a “pond” or inkwell filled with absorbent silk or cotton waste soaked with ink. As the line is let out, and with encouraging pressure applied by the user, it soaks up ink from the inkwell.

In Japan, a wooden bob called a “karuko” with a sharpened steel pin is attached at the line’s far end. The workman pushes this pin into the surface of the wood being marked to secure the end of the line in place for marking. 

To use the sumitsubo, the workman stretches the damp inkline over the surface of the object to be marked, secures it in the desired position at the far end using a pin, weight, or helper, reels out and stretches the line, picks up the line with his fingers and releases it snapping an inkline. There are other more subtle actions that the user must perform at the same time, but this is the essence.

Depending on the user’s skill and the available line, a perfectly straight line can be marked on a flat, level surface to many meters in length.

The ink line has several undeniable advantages over the Western chalk line. First, the line it leaves is narrower and less “ fuzzy,” sufficient for fairly accurate carpentry work, much more precise than the typical chalk line.

Second, it is not as easily rubbed off or blown away as chalk.

Third, while inks of various colors can be used, black is most common and contrasts nicely with most building materials, but red is another traditional color. Nowadays, ink can be purchased in a rainbow of colors, some in permanent ink and even some that glow-in-the-dark.

The standard variety of ink used with sumitsubo is not entirely waterproof and if applied to a non-absorbent material like stone or steel, will not endure a rainstorm well. There are waterproof inks available, however, and of course the standard trick of using a spray can of clear lacquer to seal the snapline works as well with ink lines as it does with chalk lines.

History and Design

As your humble servant has mentioned in previous articles, the marketplace development that makes it possible to purchase completed woodworking tools is fairly recent. In previous centuries and millennia, when material costs were high and labor costs low, craftsmen would commission a blacksmith to make the metal components of their tools, but would make the wooden components themselves. In Japan at least, the sumitsubo too was made by the individual craftsman and became an opportunity to display both his skills and imagination, yielding unique, beautiful, and even bizarre tools.

There is neither adequate time nor space in this insignificant little blog to go into the evolution of sumitsubo design in any detail, much less the design variations, but the Takenaka Tool Museum’s website has pictures of representative examples.

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An old “Ichimonji” style sumitsubo. These squarish sumitsubo have their own charm, but are not as functional or convenient as later designs.
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This antique sumitsubo shows the design evolution of the tool with the narrow tail, which is easily held, the large reel which not only holds more line but helps the line dry retarding fungal growth, the wide and shallow pond, and the ceramic ferrule for the line. The owner used this tool exclusively for red ink. This sample does not have a crank for working the reel, typical of Western Japan.
A fancier craftsman-made version of the sumitsubo above, with a smaller pond, a hand crank, and a more elegant wave motif

The style used for the last 200 hundred years or so is shown at the top of this post, and in the photo below. The major improvements include a larger ink pond designed to both hold more ink and to better accommodate the bamboo sumisashi inkpen used for layout, a larger, more exposed reel to hold more line, making it quicker to reel in, and providing better ventilation to reduce mildew, and a narrower, easier to grip tail containing the reel greatly improving functionality and reducing fumbling and damage.

A typical sumitsubo nowadays with crane and turtle facing each other across the ink pond, no doubt talking about sports scores. Zelkova wood

The carving seen in sumitsubo has meanings, of course, which varied with the craftsman and popular whim. The most popular style nowadays has a turtle and a crane facing each other across the ink pond. In Japanese mythology, both are considered lucky, with the crane said to live 1,000 years and the turtle 10,000 years. The turtle normally has a hair skirt flowing behind.

A very artistic craftsman-made sumitsubo with a peony blossom and Chinese lion holding court at each end of the ink pond, and a lotus leaf reel. These three symbols hark back to a famous Japanese Noh play titled “Shakkyou.” The lion in mythology is the king of beasts. It drives away demons and evil forces and protects against disease. The peony is the king of flowers. The lotus is a thing of grace and beauty that lives in, yet floats above the dirty mortal world, and with its roots purifies it. A potent symbol in Buddhism as well. However carved this sumitsubo was well-educated, but the size of the lion on his precarious perch would limit the practicality of this tool.
Bottom view. Notice the opening below the reel to intended to promote air circulation
A side view of the Chinese lion, facing away from Gentle Reader. No offense intended, of course, but dignity must be maintained.
A professionally-carved sumitsubo by Kimura Isaburo showing lotsu leaves surrounding the ink pond with a tiny frog poised on the rim
A closeup of the lotus ink-pond’s froggy.
Another sumitsubo carved by by Kimura Isaburo. This one too has a tiny frog on the rim of the ink pond, but instead of reposing, he is preparing to jump to escape the snake on the opposite edge. The body of the snake wraps around the wheel and tail of the tool.

Dragons are another mythological motif seen in sumitsubo, being a fierce but noble and benevolent creature in Japanese tradition

The reel end of the sumitsubo typically incorporates water or wave details, perhaps related to the ancient Japanese motif of wagon wheels in flowing water.

The last sumitsubo maker in Niigata Prefecture was Mr. Tamaki (RIP). Those Gentle Readers who have visited Kezuroukai competitions in Japan may have seen him doing exhibitions. Here is a link to a video of him making sawdust.

Here are a few links to videos of sumitsubo in use: Link 1 Link 2 Link 3

Here is a link to a video of a huge (2.3 shaku = 700mm = 27.4″) sumitsubo by a famous Niigata craftsman named Ichimonji Masakane. The size brings the carving details into focus. This is of course not a practical tool, but was created for decorative purposes. Once, every major tool store had a similar sumitsubo on display. If you visit Suiheiya in Tokyo you can see similar examples.

The sumitsubo is a tool Western woodworkers could benefit from when making straight layout lines because it’s not only cheaper, more convenient and more reliable than a long steel or wooden straightedge, it produces a finer, easier to see, and more indelible mark than a chalkbox can.

The sumitsubo was once said to be the symbol of the master carpenter, the craftsman that created the design and performed layout of major aspects of a construction project. Even today, older carpenters prefer the wooden sumitsubo and inist that it does a better job. I suppose every generation in human history had similar attachments to older ways and older tools. But I have a hand-carved Zelkova wood sumitsubo mounted under the lid of my toolbox. Does that make me an old fart?

A drachma for your thoughts.

YMHOS

A sumitsubo at work.

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

Please share your insights and comments with everyone 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 fortuitous crane do a damp doodoo on my head.

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The Matsui Precision Notched Straightedge

Matsui Precision Bevel-edged Straightedge with notch

You cannot teach a crab to walk straight.

Aristophanes

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:

  1. 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;
  2. 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.
  3. 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.
  4. 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;
  5. 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:

  1. 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.
  2. 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.

Feeler Gauge

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.

Beveled Edge

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.

The Notch

The Matsui Precision Straightedge being used to check the sole of a 70mm finish handplane with a blade by Sekikawa-san. The notch fits over the cutting edge so one can check the sole with the blade protruding as it will be in-use. In this photo the blade has been extended waaay too far out of the mouth to make it easy to see the cutting edge. Please notice the light showing between the straightedge and the sole indicating that something is not right. The wedging pressure of forcing the blade to project this ridiculous amount has warped the block so that the most important part of the sole, the area directly in front of the mouth, is not touching. The point is that the notch makes it possible to check the sole with the blade projecting the intended distance, a job simply not possible with an ordinary straightedge.

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.

YMHOS

Matsui Seimitsu Precision Squares

Maestro Bruno Walter 1876~1962

By concentrating on precision, one arrives at technique, but by concentrating on technique one does not arrive at precision.

Bruno Walter

We would like to introduce some excellent tools made by a company called Matsui Seimitsu Kogyo located in the city of Sanjo in Niigata Prefecture in Japan. We have been using this company’s products for many years and have started carrying a few by popular demand. The time has come to share these with our Beloved Customers in general.

Matsui Seimitsu Kogyo translates to “Matsui Precision Industries,” but I’m just going to call them Matsui Precision. The company has been around for over 100 years. They may not be the largest manufacturer of precision tools in Japan, but their reputation is unsurpassed.

Allow me to digress for a moment while I grind these oak galls to make some ink. Just about out, you see. Anyway, as you can probably tell from my posts to this blog so far, and which will become even more obvious in the future, I love ancient tools and learning how beautiful work was done by determined people using basic, even crude tools. But I am also fond of excellent refined handtools that help me do a better job more efficiently. I am always on the lookout for such tools, and this post is about one such tool I discovered. One thing I like about this tool is that while it is essentially unchanged from the days when Noah was knee-high to a grasshopper, Matsui Precision has subtly improved the ancient and lowly square in ways that are not immediately obvious. For one thing, it really is a “Precision Tool,” even though you wouldn’t think so just by looking at it.

The idea of using “precision tools” for woodworking is offensive to some. I have seen online discussions about using precision tools for woodworking induce psychotic events in some amateur woodworkers. Perhaps the very thought of such tools triggers hallucinations of digital micrometers swooping through their dreams while pissing down on the eternal beauty flowing from their masterful hands. Or perhaps they imagine the smelly poor-quality Chinese-made tools they buy in bundles from Harbor Freight to be more expressive of their artistic intentions than the cold precision tools of the sort less artistic machinists use. To the former I say “Don’t drink alcohol with your medications.” To the latter I exhort: “Extract your head from your nether regions and behold the light of civilization!” 

Anyway, that’s enough ink to last a month, so enough free psychoanalysis. Let’s get back to Matsui Precision Squares.

They have six distinct advantages over almost any other simple square you will find:

  1. Precision: Unlike any square ordinarily available to woodworkers, these are manufactured and certified in accordance with Japan Industrial Standards (JIS). The relevant standard is JIS B7516 (2005). The hardened steel model (SY Series) is rated Grade 1, and the graduated model SM Series) is rated Grade 2. Accordingly, these squares precisely measure 90°. Without using other precision instruments the only way to confirm this claim is with another high-precision machinist’s or diemaker’s square. The MP square will pass this test, not to woodworking tolerance, but to machinist’s tolerances. We guarantee it.
  2. Lightweight and Handy: You will not find a precision square lighter or handier. The blade (long leg) and stock (short leg) are relatively thin, light in weight, and handy to use, unlike machinist’s squares and combination squares with their thick, heavy, clumsy, flat stocks and blades which make it difficult to see light showing between them and the workpiece. The Matsui blade is relatively thin making the square easy to use for woodworking.
  3. Durable: The stock and blade of both SY and SM series tools are joined by spot welds, unlike all but the most expensive machinists squares; Not a compression joint, not glued, not bolted, not pinned. They are not indestructible, of course, but the stock or blade will bend or melt before this connection fails.
  4. Corrosion-Resistant: both blade and stock are stainless steel so they won’t rust even if used and stored in constantly humid conditions, even if you have sweaty hands.
  5. Hardened: This feature is most important in my opinion. The blade and stock of the SY series squares are hardened, a very unusual feature. For the woodworker, this means that the blade will better endure the scraping and shaving action of steel scribes and heat-treated marking knives used in layout, and will stay straighter much longer than all but the most expensive machinist’s and diemaker’s squares.
  6. Relief Cut: The stock has a small half-circle notch cut into where it meets the blade to prevent wood shavings etc. from jamming between the blade and/or stock preventing them from making clean contact with the workpiece ruining accuracy, an important detail indeed.

In short, the Matsui Precision square will help you do better woodworking, easier, and for many years.

We carry two models of Matsui Precision squares. The first is the SY Series pictured below, with a hardened stainless steel blade but without graduations. The stock is hardened to Rc54~57 and the blade to Rc48~52. This is the tool we use and recommend for layout using a marking knife.

The SM series is different from the SY Series in three ways, reflected in the lower price. First, the blade is not hardened. Second, it has deeply etched graduations (not laser etching) which are perfect for using with a scribe or marking knife because the tool’s tip can get into the graduation for positive indexing. And third, the level of precision is one level lower at JIS Grade 2. The graduations include a √2 scale useful for determining the diagonal distance of a square by measuring a side.

If you are tired of squares that aren’t square, that are bulky, heavy, and clumsy to use, that are destroyed by a single drop, or that get eaten alive by your marking knife or scribe, then you should give these a try. You’ll never look back.

If you would like to purchase one, please inquire using the form below.

Matsui Precision Hardened Stainless Steel Squares (w/o graduations) Model SY-15
Product IDNominal Size (mm)Blade lStock lStock t¥ Price
SY-550524086,270
SY-770725686,270
SY-101001057086,270
SY-151502029986,820
SY-2020025212288,690
SY-252502521481012,320
SY-303003021761015,180
Matsui Precision Hardened Stainless Steel Squares (w/o graduations)
Matsui Precision Stainless Steel Square (w/o graduations) Model SM-10
Product IDNominal Size (mm)Blade lStock lStock t¥ Price
SM-550524083,080
SM-770725683,080
SM-101001127083,080
SM-121201408583,080
SM1515017010083,300
SM-2020022512084,840
SM-2525027514510.56,820
SM-3030032517310.58,800
Matsui Precision Stainless Steel Squares (w/ graduations)

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. May my square always lie to me if I lie to you.