Japanese Handplanes – Part 4: Fitting Blade & Body

After tumbling down the rabbit hole, Alice discusses her options with her new friends Gryphon and Mock Turtle. After perusing this article, I hope Gentle Readers will be less discombobulated than poor Alice, less tearful than Dear Mock Turtle, and less indignant than Noble Gryphon.

A Bruise Is A Lesson… And Each Lesson Makes Us Better.

George R.R. Martin, Syrio Forel, Game of Thrones,

In this the fourth post in our series about the Japanese hiraganna handplane we will discuss how to fit the plane’s wooden body to the blade thereby improving the tool’s performance.

As is the case for most of the posts in this blog, this one too is intended primarily for the information and entertainment of our Beloved Customers, but all well-behaved Gentle Readers are welcome to partake. Bon apetit.

Why Fit Body to Blade?

Beloved Customers may wonder why your humble servant is inflicting the internet with another pointless article about Japanese planes, especially since the handplanes purveyed by C&S Tools are advertised as “ready to use” when new. The purpose of this paragraph is to address this absolutely valid concern.

As mentioned in the Part 3 of the Japanese Handplane Series, Mr. Inomoto, the daiuchi shokunin that cuts the bodies from Japanese White Oak to fit the blades forged and sharpened by Mr. Nakano, does indeed do more than just cut a gap for a blade to slot into, but fits the blade to the body so it is able to cut a decent shaving before it leaves his workshop. However, due to cost considerations and practical limits to his prophetic talents and clairvoyant insights regarding who will eventually own each plane and their preferences for the blade-body marriage, he fits the blade on the tight side, assuming the end-user will adjust the body to best suit his own purposes. Ergo the paragraph titled “Plane Philosophy” in Part 3.

I suspect relatively few Beloved Customers have given the subject serious thought, but it is nonetheless true that each owner of a Japanese plane must develop their own philosophy regarding the relationship between blade and body, and if they deem it necessary, adjust their plane body accordingly.

This article assumes Beloved Customer has decided to refine the fit between blade and body, and instructs in how to make those refinements. Are they absolutely necessary? Nah. Will they make a difference? Yes, but the degree of improvement obtained will vary from plane to plane and person to person.

Nonetheless, your humble servant recommends Beloved Customers, especially those interested in obtaining professional-level plane maintenance and usage skills, to perform the operations described in this and future articles in this series. You’ll be glad you did even if it may take some years for the benefits obtained to become evident.

So with that out of the way, let’s assemble the tools we will need to make some righteous sawdust.

Tools

The following is a list of tools recommended for this job.

  1. Wooden mallet for striking the blade and body;
  2. Carpenter’s pencil and/or marking pen;
  3. Masking tape to protect the wooden body from oily fingerprints;
  4. Vernier caliper and/or divider for measuring and comparing;
  5. Various chisels (e.g. 3mm, 6mm, 9mm usunomi paring chisels);
  6. Metal file (to be modified) or a 15~18mm wide chisel (to be modified).
The tools needed for fitting the body to the blade. The chisel next to the vernier caliper is an old Sorby modified especially for working on plane beds and gifted to me by Chris Vandiver. Thanks, Chris.

Regarding the modified file or chisel listed above, this is a push scraper, an ancient tool once commonly used for precision metalwork. Your humble servant uses it to shave the bed to fit the blade. You can make this tool as wide as you wish, but please note that if the blade of either file or chisel is too wide, your shaving efforts may not produce smooth results.

You can easily make this scraping tool from a chisel or an old file by grinding a flat on the end of the file or cutting edge of the chisel square to the centerline of the blade and at an 80~90˚bevel angle. Then hone this square cutting edge and at least one of the two adjoining surfaces to 1000 grit. Voila.

If you use a file you will want to attach a handle to its tang to avoid getting red sticky stuff on your pretty wood.

If you prefer to use a regular chisel, that’s OK too, but you will find this scraper does a cleaner job with less effort.

Blade Preparation

This explanation assumes the blade is sharp and the ura is in good shape. If not, please sharpen the blade because it will of course affect the fit of blade to body.

While you are at it, check that the side edges of the blade are free of burrs or rough grinder marks which might abrade the grooves after some use. Some grinder marks may be unavoidable, but if the sides feel rough and abrasive to the back of your hand, smooth the edges a little using a sander and/or sharpening stones.

In addition, please make sure the right and left clipped corners of the blade’s cutting edge, called “ears,” are properly trimmed, meaning that they are ground large enough to reduce the width of the sharp cutting edge so it fills the width of the plane’s mouth but does not extend into the grooves, because if it does get into the grooves, shavings will become jammed between the blade and groove wasting your energy and leaving nasty scuff marks and sometimes even tracks on the planed surface. それは困る.

When sharpening a plane blade, therefore, it is important to check and trim these ears periodically. A few passes on a diamond plate or rough stone will do the job; It doesn’t need to be pretty, and the ears don’t need to be sharpened because they never touch the wood.

The disassembled plane used as an example in this article, a 70mm finish plane with a Blue-label steel blade hand-forged by Mr. Nakano Takeo and a Japanese White Oak body by Mr. Inomoto Isao. An excellent tool.

Checking & Tuning the Mouth

Beloved Customers won’t need to worry about this, but Gentle Readers fettling plane bodies made by themselves or others should be careful the first time they adjust the blade’s cutting edge to project through the mouth to ensure there is adequate clearance because if the mouth isn’t wide enough to allow the cutting edge to pass through cleanly with a little clearance to spare, the blade may chip out the sole.

If there is any question about the mouth/blade clearance, the first time you extend the blade through the mouth, press the plane sole-down on a piece of clean wood while tapping the head of the blade with your mallet to make a zero clearance cut at the mouth. The supporting board will prevent the mouth from chipping. This is also standard practice when opening the mouth of a new plane body.

Hold the plane up to a light and peer through the mouth to observe the gap between cutting edge and body. The width of this gap must be greater than zero, but how wide it needs to be will depend on the thickness of the shaving you intend to cut.

Ugly tear-out can be minimized and the polish of the planed surface increased by having a tight mouth. Indeed, the tightness of the mouth and the area of the sole directly in front of the mouth applying uniform pressure on the wooden surface being planed up to the last .001 millimeter in front of the mouth is critical for exceptionally fine tear out- free cuts. On the other hand a mouth gap that is too narrow to pass the intended thickness of shaving will jamb every time, so the user must balance the width of the mouth, the desired shaving thickness, and blade projection to obtain good results.

Here is wisdom: repeatedly jamming packed chips and shavings into the mouth is not only hard on the blade, but it will damage the mouth, so before this happens too many times, you want to either adjust the mouth or your expectations for shaving thickness.

To open up or adjust the mouth, cut a hardwood guide block to use with a chisel to pare the mouth opening, and clamp it to the sole. The angle of the block will vary with the angle of the blade.

Then using an exceptionally sharp paring chisel and this guide block, take minute shavings at the mouth using skewed strokes. A paring chisel with a three-hollow mitsuura ura is ideal for this task, but any sharp chisel with a longish blade will do the job.

Body Protection

This process will involve graphite pencils, marking pen ink and fingers, so to keep the wooden body from looking dirty, please cover the top and sides with a low-tack masking tape. In this example, I used a pretty pink tape.

Adjusting the Blade to the Mouth

As mentioned above, the blade fits into and is clamped in-place by the two tapered grooves in the body. Sometimes the fit between the side edges of the blade and the bottom of these grooves is too tight. This can occur in a new plane if the body was improperly cut to begin with, but the most common cause is shrinkage of the body due to humidity changes.

Of course, the wooden body will change dimensions with changes in ambient humidity, while the blade won’t. If a plane is shipped from a wet climate like Japan (at some times of the year) to a dry climate like the Mojave Desert (all times of the year), for example, the body may shrink in width developing tremendous pressure on the side edges of the blade, sometimes enough to crack or split the body. Therefore, if you are located in a dry climate and acquire a plane from a wetter climate, it may be wise to remove the blade and let the body acclimatize for a week or so.

As mentioned above, the blade is tapered in width, being wider at the head and narrowest near the cutting edge. This is intentional. Ideally, you want the side edges of the blade to just kiss the bottom of the grooves where they exit the top surface of the body, and not touch the bottom of the grooves anywhere else. This type of fit will to make it easy to make minute right or left adjustments to the cutting edge’s projection by tapping the head of the blade right or left.

Obviously (and this is an important point to understand), if both of the blade’s side edges are in close contact with the bottom of the grooves their full-length, this important method of adjustment will no bueno.

Use you vernier caliper or divider to check that the the blade does indeed become narrower in width from the point where it exits the grooves at the top surface of the body and the point where the cutting bevel begins. If it doesn’t, you will need to grind in some taper. How much? Mr. Nakano’s blades typically taper the amounts shown in the photos above, but they are handmade and each one is little different.

The distance measured between the blade grooves where the blade makes contact at the top of the grooves. Please notice that this distance is slightly less than width of the blade at this point as shown in the photo on the right above.

In any case, please check the body provides adequate clearance to just accommodate the blade’s width. Mark 1 Eyeball is often good enough for this task, but a divider is better and a vernier caliper is ideal.

Make a final check by applying marking pen ink to the sides of the blade 1cm down from where the blade would normally exit the grooves at the top surface of the body. More ink is not necessary.

If some paring of the grooves is necessary to provide adequate clearance, please remove no more wood than is absolutely necessary.

Groove Maintenance

A common problem we see with old planes is cracked and split bodies caused by the tapered blade becoming shorter over the years due to repeated sharpenings, and therefore the edges of the blade exerting excessive pressure on the bottom of the grooves when a careless user mercilessly pounds the blade into the body. This sort of damage is entirely avoidable through intelligent means, but some illogical, shortsighted nitwits advocate paring the bottom of the grooves of new planes to create a gap of 2~2.5mm between the groove and blade to accommodate all the reduction in length the blade may experience over many years of service at once. To this practice, your most humble and obedient servant can only respond “Poppycock!”

Why do I object to what seems to be a logical solution? Glad you asked.

If you chisel out a big gap between the side edges of the blade and bottom of the groove, not only will you unnecessarily weaken the body by severing continuous wood fibers at the narrowest, weakest, most critical point of the body (think about it real frikin hard), but the pivoting action required to adjust the blade’s projection right and left by tapping the head right and left will become more difficult, while at the same time the blade will become less stable in the body.

I write this based on bitter experience obtained from following bad advice received before I knew better, and later being mocked by more experienced craftsmen who saw my silly error.

Beloved Customers will of course have purchased a high-quality plane from C&S Tools, with a blade hand-forged by Mr. Nakano Takeo and Japanese White Oak body cut by Mr. Inomoto Isao, but just in case you are working on a lower-grade tool, here are some things you need to check.

The solution to body damage due to shrinkage of body or blade is simple: (1) Pay attention to the fit of the blade in the grooves; (3) Adjust the clearance when appropriate, and; (3) Avoid excessive use of recreational mushrooms which may dull the senses and cause chronic tool neglect.

In other words, when you notice the blade becoming tight in the grooves, simply pare the bottom of the grooves a nat’s mustache hair deeper. Don’t get carried away because a little contact is a good thing!

Our 6mm and 3mm usunomi paring chisels are ideal for this job. but standard oiirenomi chisels can accomplish the task too.

Another option is to grind the sides of the blade making the blade a little narrower in width.

Beloved Customers have the choice of learning from your humble servant’s stupid mistakes or from their own. Of course, I suppose there’s always the default option too many lost and wandering souls select of neglecting to learn anything at all…

Fitting the Bed to the Blade’s Back

Assuming Beloved Customer has completed the checks and adjustments in the previous sections, the general steps for fitting the bed to the blade are as follows:

  1. Begin by rubbing the back of the blade from where the cutting bevel begins to the end of the steel lamination with your carpenter’s pencil giving it decent coat of graphite. Marking pen ink or Dykem works too.
  2. Insert the blade into the grooves and tap it with your mallet (not a metal hammer!) until the cutting edge is nearly projecting from the mouth. You may need to really wack the blade hard 5~10 times to accomplish this the first time.
  3. Next remove the blade by holding the plane in your hand and alternating strikes on the right and left sides of the chamfer on the body behind the blade’s head. Don’t strike the flat end of the body! The blade should wiggle out after some less-than-gentle persuasion. If your plane doesn’t already have a pretty 6~8mm wide chamfer cut on this edge, please make one.
  4. Examine the bed. You will notice how the areas in contact with the blade are now marked with graphite. We need to pare or scrape down these contact points to achieve a more uniform contact.
  5. Use your chisel or scraper tool to carefully shave down the high spots marked with graphite. Cut/scrape only those areas marked with graphite. Before you begin making sawdust, however, please be careful to not remove any wood from any of the three surfaces inside each side groove for now. You need to sneak up on the final shape of the bed like a kitten stalking a grasshopper, with eyes wide open, gently and a little bit at a time. It would be a serious mistake to try to make a perfect fit after only a few passes.
  6. Repeat steps 2~5. You may need to do this dance 10 times to get it right. You won’t need to apply more graphite each time, just rub the back with a piece of cloth to redistribute the graphite. Or you can use your carpenter’s pencil again. With each iteration, the graphite marks left on the bed will increase in number and become larger. You want to be able to seat the plane blade with only three or four medium strikes with your mallet, and make fine adjustments with just a few more. At no time should your plane squeal a complaint.
  7. When the blade can be easily seated with 3 or four medium wacks of your mallet, use a metal file to lightly smooth out the rest of the bed. Perfection is neither attainable nor should it be sought.
The bed before applying graphite and any shaving. Mr. Inomoto Isao does a nice job, so contact is good, but still tighter than I prefer. The No.13 is a mark he made to keep blade and body matched. Notice the “tsutsumi” shelf cut at the bed just inside the mouth. This is a nice, pretty detail that aids in preventing the blade from “sniping” the ends of narrow boards, but sometimes it gets in the way, and after much use, it becomes so thin it must be removed. It is neither necessary nor sacred.
The back of the blade has been rubbed with a graphite pencil, and is being tapped into the body. It takes some forceful strikes to get it into position. Notice the purty-pink low-tack masking tape applied to the body to help keep it free of graphite fingerprints. My planes seem to appreciate brighter, feminine colors.
Graphite marks left on the bed from the first insertion of the blade. Not terrible, but contact could be better.
Shaving the bed with a scraper chisel the first time
Shaving the bed with a scraper chisel the second time
The bed after shaving it the third time.
The completed bed following final cleanup with a file. The blade can be inserted with three medium mallet strikes, and fine adjustments made in 3~4 strikes. The blade does not tend to twist out of alignment. Notice the graphite marks left on the tsutsumi shelf where the blade has contacted it.

The Peppermint Twist

Now that the bed is fitted to the blade, we need to return our attention to the grooves.

If one groove is pinching the blade more than the other, the blade will want to twist out of alignment. This can be very irritating.

The surfaces inside the grooves touching the ura and back of the blade should be clean and straight. In any case, unless it causes a serious performance problem, it’s best to leave these surfaces alone for a while because after inserting and removing the blade several times the fit may improve automatically.

If the blade continues to twist out of alignment, however, determine where the high points are on the surface of the groove touching the blade’s ura. You can do this by peering into and through the mouth while shining a light into the groove.

Once you have identified the high spot(s) glue a piece of fine sandpaper to a thin stick of wood and sand it down a little bit at a time between inserting and removing the blade frequently to check the fit.

Don’t sand down the surface inside the groove which contacts the blade’s back unless absolutely necessary because this will effectively open up the mouth, something we want to avoid for as long as possible.

With this, your plane’s hard, sharp blade and soft wooden body should fit together like hand in glove. It may sound like a lot of work, but it usually isn’t. In fact, besides prepping the blade, the whole process can usually be completed in less time than it takes to read about it.

So far in this series I have provided a lot more detail and explanation than I have ever seen in writing elsewhere. It took me many years of fumbling in the dark, much consultation with older, more experienced craftsmen, no few curses and ungentle slaps to the back of the head, and numerous expensive mistakes to learn these things. I hope Beloved Customers profit from them.

In the next post in this ongoing adventure towards the perfect Japanese handplane we will shift our attention to fitting the chipbreaker (uragane 裏金) to the blade.

See you again next week, same bat time same bat channel.

YMHOS

Alice asking advice of a caterpillar sitting on a magic mushroom, smoking magic mushroom.

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 ears of all my plane blades become clogged with wax.

Other Posts in the Japanese Handplane Series:

Japanese Handplanes – Part 3: The Blade

A beautiful and even poetic plane blade forged by the famous Chiyozuru Korehide. The carved inscription reads ”Shin, Un, Mu” meaning “God, Cloud, Dream.”

The best steel doesn’t always shine the brightest.

Joe Abercrombie, The Blade Itself

In this the third post in our series about the Japanese hiraganna handplane we will focus on iron and steel and discuss some unique characteristics and even some philosophical aspects of the hiraganna blade. Why? Because to become proficient at using and maintaining a tool, one must understand it more than just superficially.

In addition, we will briefly examine the story of a single plane blade made for a famous carpenter by a famous blacksmith.

The Shin Un Mu Blade 神雲夢の刃

The plane blade pictured at the top of this article was forged 6 years after the end of World War II by a famous Tokyo blacksmith named Chiyozuru Korehide for a famous Tokyo carpenter named Mr. Nomura Sadao. The engraving on the back by Chiyozura states the blade (and matching chipbreaker) was made by him for Nomura Sadao and completed on June 4, 1951. Chiyozuru charged Mr. Nomura ¥10,000.

You will notice that it looks different from most plane blades in that it lacks the beveled “ears” at the right and left corners of the blade’s cutting edge commonly seen in Japanese plane blades.

The beveled corners absent from this blade are necessary with ordinary blades to prevent the cutting edge from extending into the grooves on each side of the blade opening used to retain the wedge-shaped blade in-place. Without the bevels, shavings become jammed between the groove and blade leaving unsightly and inefficient marks and tracks on the surface of the wood being planed. More on this below.

The blade in question, however, has rabbets cut into the jigane at the left and right edges of the blade so the ura area is thicker than the sides which fit into the retaining grooves, and the cutting edge, therefore, does not intrude into the grooves, making beveled ears unnecessary. This is a very logical solution, although it was not actually invented by either Chiyozuru or Mr. Nomura. Apparently, Mr. Nomura first saw the design at a school. He then made a wooden full-scale model and asked Chiyozuru to forge it for him.

While it is an elegant solution to a real performance issue, it is much more difficult to make this style of blade than the conventional one, and so never became popular.

On the subject of materials, Chiyozuru is well known for preferring to use imported steel, mostly from England, instead of traditional domestic Tamahagane steel. Although the source of the soft jigane is uncertain, there can be no doubt the steel lamination is made of British high-carbon steel.

Gentle Readers are no doubt aware that Japan has always been a land of many man-made and natural disasters, earthquakes and widespread fires being especially common. To protect this important blade from being lost to posterity, as were so many valuable things during the war, upon his retirement Mr. Nomura entrusted the blade to the Takenaka Carpentry Tools Museum located in Kobe, Japan.

Ironically, a large earthquake struck Kobe on January 17, 1995 killing over 6,400 people and tearing the city a new one. Fortunately, while the museum’s exhibits were jumbled up, this blade was not damaged.

Upon the relocation of Mr. Nomura to the big lumberyard in the sky, his heirs formally donated the blade to the museum where it remains to this day.

The blade has four Chinese characters engraved into its face, the meaning of which is a bit of a mystery. From top to bottom they read 神雲夢, pronounced “Shin, Un, Mu” which translates directly into English as “God, Cloud, Dream.” No doubt there is some deep poetic meaning being expressed through these three characters, but the intended meaning is far above the poor understanding of your humble illiterate servant.

Interpretations from Beloved Customers and Gentle Readers are welcome.

Definition of Fettle

While we are on the subject of literacy, I would like to clarify the meaning of a word pertaining to working on tools, and especially planes.

Gentle readers have no doubt heard the word “fettle” used in the phrase “fine fettle,” usually referring to someone being in good health or physical condition. But it has other, older meanings.

In the British dialect, it means to “set in order,” or “get ready,” from Middle English fetlen to shape, prepare; perhaps akin to Old English fetian to fetch.

Your humble servant uses fettle as a verb, mostly when truing a plane or other tool, but also for adjusting it.

Never let it be said that the Gentle Readers of the C&S Tools blog are less than exquisitely erudite and edumacated.

Blade Details

Misunderstandings abound and deep, pungent rivers of BS often burst their banks when the details of the Japanese hiraganna plane’s blade are discussed; Buckets, mops and even garbage pumps are necessary to clean up the mess. I despair: What to do, what to do?

While it appears to be a simple, crude, even haphazard component to the uninformed, the design of a well-made blade is subtle and its execution elegant. I am confident Gentle Readers willing to forego both the temptations of ridiculous rumor and magic mushrooms for a time will quickly understand. So without further ado, let’s turn on the pumps and get our mops moving.

Laminated Construction

The blade is made by forge-weld laminating a piece of hard high-carbon steel to a larger piece of softer low/no carbon steel/iron. These details are discussed in more detail in the two posts linked to below. It is important to understand these details if Beloved Customer intends to become skillful in using and maintaining Japanese planes.

Sharpening Part 8 – Soft Iron 地金

Sharpening Part 9 – Hard Steel & Soft Iron 鍛接

The Ura

The blades of quality Japanese chisels and planes have a hollow-ground area on the blade. In the case of plane blades, it is located on the surface your humble servant calls the “face,” which is oriented upwards when installed in the body. An accurate understanding of this structural detail is essential to using and maintaining the Japanese handplane. We discussed this detail in a previous post linked to below. Please review this post if you haven’t done so previously.

Sharpening Part 10 – The Ura 浦

We discussed how to perform periodical maintenance on the ura in an earlier post. Oh joy!

Another plane blade by Chiyozuru Korehide engraved with many of the brands he used during his career. It has a sweet, sculptural ura.

Blade Retention

The blade of the Japanese handplane is held firmly in-place by the wedging action of the blade in the tapered grooves cut into each side of the mouth opening. This arrangement eliminates the dedicated wedges, usually made of wood, used since at least Roman times to retain the blades of Western planes. It also makes irrelevant the widgets and linkages common to modern planes such as the Bailey-pattern, considered by many to be the pinnacle of plane design in the West. Simple is best, don’t you think?

A common misunderstanding about Japanese planes is that pressure between the wooden body and the back of the blade is necessary to both lock the blade into the body and to eliminate chatter resulting from blade vibration. In response, your humble servant can only increase the speed of the garbage pump and say “poppycock!”

Except in the case of a poor quality body, or one damaged through improper setup and maintenance, the friction acting on the right and left sides of the blade generated by wedging action in the grooves must be sufficient to hold the blade in-place without any pressure on the blade’s back.

And unlike the potato chip-thin blades common to many Western planes, the quality Japanese plane blade of the sort we carry with its relatively thick, laminated construction may have a few female characteristics, such as beauty and elegance, but despite fitting into a truly tiny mouth it simply will not chatter (as you know, it’s chisels and squares that love to gossip).

While some degree of uniform contact between the wooden block and the back of the blade is desirable to steady the blade in-use, many fit their blades (or perhaps “neglect to properly fit their blades” would be a more accurate description) to develop high pressure between blade and bed, making it difficult to adjust the blade and distorting the body unnecessarily. In extreme cases, this pressure can even push out the sole, preventing the plane from working entirely, a situation that has shaken many a poor woodworker to the core! Pixie involvement cannot be dismissed.

We will discuss this subject more in future posts.

Lengthwise Taper

A casual observation reveals that the blade is tapered in thickness along its length, being thickest at the head, and thinnest at the cutting edge bevel. The purpose of this taper is simply to wedge the blade into the grooves in the body. Please note that this wedging action does tend to cause the body to deflect to some degree, something which must be taken into account when fettling the sole, a subject we will discuss in a future post in this series.

Transverse Taper

The blade is also tapered in its width, being widest at the head and narrowest at the cutting bevel.

Ideally the side edges of the blade are in intimate contact with the grooves only where they exit at the top surface of the body, but should normally have no contact in the grooves elsewhere, making it possible to adjust the blade’s projection through the mouth to a uniform distance by gently tapping its head right and left a small amount.

Curved Back

Finally, please observe that the back (vs. the ura) of a quality blade is not flat, but is slightly hollow-ground centered around the centerline of the blade’s length. The amount of this hollow should be more-or-less uniform over the blade’s length.

One purpose of this detail is to lighten the blade’s weight, but more importantly it helps keep the blade from twisting out of alignment in-use. If you have ever made a wooden plane body to fit a blade with a flat back, you may have experienced the irritating tendency of the blade to twist out of alignment under heavy planing forces. This is typically not a concern with the Japanese design because of the curved back detail, so long as the body’s bed is well-fitted to the blade.

Since each blade and its wooden block are a little different, and not yet in perfect accord when new, fitting the body to the blade is one of the first things one must do to a new plane. This fettling operation will be the subject of a future post.

A plane blade by Mr. Ogata. Notice the curved back. Notice also the trimmed and beveled “ears” at the right and left corners of the cutting edge.

Plane Philosophy

Traditionally, everywhere planes were used around the world, a craftsman would commission or purchase the metal parts for his plane and cut the wooden body himself.

In recent history in Japan professional plane body makers called “daiuchi shokunin” 台打ち職人, which translates directly to “plane-body beater” (I kid you not) have become common. These craftsmen fit blade to body making a nearly complete retail product. The end-user, however, is still expected to adjust the fit to his preferences.

Many of these ostensibly completed planes are sold in a “sugu tsukai” 直ぐ使い condition, meaning “ready-to-use.” As witness of this, such planes usually have a wood shaving resting in their mouths when sold. However, the fit between blade and body is intentionally too tight. This is where philosophy comes into play.

There are regional preferences in Japan when it comes to tools, including sickles, saws, axes, adzes, chisels and of course plane blades. In far Eastern Japan, especially the Tohoku area and Hokkaido, thicker, heavier plane blades are preferred, whereas in Tokyo and Western Japan, thinner blades are traditional.

But while discussions of these differences make the hearts of historians go pitter patter, they are irrelevant to persons living outside Japan, so we will ignore them for now.

There are two general, practical approaches to blade size and fit. Carpenters tend to like stiff, thick blades that fit very tightly into the body because they tend to retain their settings better in the rough conditions of a construction jobsite. The downside to the thick blade is that it’s heavier, it takes longer to sharpen, and it’s more difficult to make fine adjustments to.

Craftsmen that do finer, more precise work such as joiners, sashimonoshi, furniture makers and cabinet/tansu makers prefer thinner blades that are quicker to sharpen and easier to frequently adjust to make fine, precise cuts.

We have Mr. Nakano forge the blades for our planes more in the Tokyo style: thicker than some but thinner than most.

Not knowing who will purchase the plane, unless directed otherwise most daiuchi shokunin cut tight-fitting bodies more suited to the carpenter, and assume the user will adjust the blade/body fit to their preference. This is a great idea, and probably the only practical solution, but the reality is that too often the pressure on the back of the blade is so high it ends up creating problems for the user unless corrected.

Too many inexperienced users of Japanese planes, especially amateurs located overseas, learn how to use Japanese planes without knowledgeable supervisors or fellow workers near at hand to notice their mistakes, wack them upside the head, and tell them how to correct their errors (welcome to the gentle world of the Japanese craftsman), and consequently never really figure out how to setup, fettle and maintain Japanese handplanes. I think this is one reason why so many Western woodworkers who give Japanese planes a try fail to ever get satisfactory performance out of their planes and eventually become frustrated.

While your humble servant is eager to provide Beloved Customers all practical support and encouragement, the guidance he can provide is limited by distance, the written word, and the undeniable fact that he is a gentleman of great refinement and exquisite sensitivity (She Who Must Be Obeyed has been known to disagree, but what does she know?).

Therefore, upon making a significant mistake, Beloved Customers must instead call themselves rude names and slap their own heads to aid learning retention. May I suggest “Blockhead” as an appropriate self-imprecation in the case of planes? (ツ)

Conclusion

In this post we considered some of the unique design features of the Japanese hiraganna handplane’s uncompromising and bitterly sharp iron and steel blade.

We even examined a historically-important, unusual, and exceptionally beautiful blade made by a famous blacksmith for a famous craftsman with curious engraving of unfathomable meaning. You can’t make this stuff up.

In the next adventure we will turn our attention to the body of the Japanese handplane, the softer, gentler, wooden component with the mouth that directs and controls the work of cutting.

And I promise we will make some sawdust.

YMHOS

Chiyozuru Korehide (1874~1957), the blacksmith of the blade shown above.

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

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

Other Posts in the Japanese Handplane Series:

Sharpening Japanese Tools Part 30 : Uradashi & Uraoshi

And now at last it comes. You will give me the Ring freely! In place of the Dark Lord you will set up a Queen. And I shall not be dark, but beautiful and terrible as the Morning and the Night! Fair as the Sea and the Sun and the Snow upon the Mountain! Dreadful as the Storm and the Lightning! Stronger than the foundations of the earth. All shall love me and despair!

J. R. R. Tolkien

This article is a continuation of, and probably the conclusion to, our “Sharpening Japanese Tools” series. The last post was one year ago and gave an example of how to employ the lessons taught in the previous 28 posts. At that time, your humble servant promised to discuss the subjects of this post at a later date. It’s later.

Why the delay? Simply because I am an excessively compassionate sumbitch who wanted Beloved Customers who hadn’t already figured out plane blade sharpening on their own to become proficient at regular sharpening operations before worrying about something as bizarre as wacking hard steel blades with hard steel hammers. After all, in the words of Miss Benatar, it’s sometimes a heartbreaker.

But now with the blog teetering on the loose and crumbly edge of the rabbit hole that is the Japanese handplane, we have the choice of either gliding gracefully into its depths or clumsily tumbling down ass over tea kettle (oh my!). Alas, we can tarry no longer.

With his article we will begin our swan-like journey by studying a matched set of operations Beloved Customers need to master to become proficient at maintaining Japanese woodworking blades, one called “Uradashi,” and a related operation called “Uraoshi. If you already have these skills, accept my highest praise. The target audience for this post, however, is those that don’t have experience with uradashi and uraoshi as well as those that want to review and improve the skills they already have.

So spread your wings and fly, my brave cygnets!

Definitions

Beloved Customers should already be aware of the the hollow-ground “uratsuki,” typical to Japanese chisel and plane blades. If not, please review the article at this link.

Uradashi is pronounced oo/rah/dah/she and written 浦出し in the Chinese characters as they are used in Japan. These characters translate directly to “push-out the ura.”

Uraoshi is pronounced oo/rah/oh/she and written 浦押しwhich translates directly to “press the ura.”

These two maintenance operations are performed to restore the blade’s cutting edge to useful condition when the thin land at the cutting edge is almost worn out. We will discuss the why and how below.

Long-term Strategy

Before we start pecking on steel, let’s consider our sharpening strategy.

Professional-grade blades are not only expensive, they are difficult to make, hard to find, and require an investment of time and effort from the user if they are to deliver high-performance results over many years. To minimize the required expenditure of time and effort, and to maximize the results delivered, we need more than just technique, we need a maintenance strategy.

In previous posts in this series we have discussed multiple strategies, some physical, some psychological, and even a few supernatural ones. The following is one I strongly urge Beloved Customers to adopt:

  1. Get the ura in good fettle, and then;
  2. Avoid working the ura on anything but one’s finest-grit sharpening stone thereafter, (with the exception of uraoshi following uradashi, of course).

Simple, no?

The ura is formed by hollow-grinding a lamination of extra-hard high-carbon steel (at least in the case of C&S Tool’s chisels, planes and knives). Because it is hard layer of steel is time-consuming to abrade, a wise craftsman will work to keep the ura as deep as possible, and the flat lands surrounding the hollow-ground ura as narrow as possible, as long as possible, thereby minimizing the area of hard steel that must be abraded with each sharpening.

But no matter how careful we are to preserve the ura, sharpening the bevel makes the blade incrementally shorter, so the day will come, at least in the case of plane blades, when the land at the ura immediately behind the cutting edge, called the “itoura,” (pronounced ee/toh/oo/rah, meaning “ thread ura” ) becomes as thin as a thread. Once it disappears, the blade will no longer function. This is the only drawback to the Japanese ura feature, and can only be solved by bending brittle steel.

Bending Hard Steel

The goal of uradashi is to cause the lamination of hard steel at the ura at the cutting edge to bend towards the ura so that when we subsequently abrade the bent ura the itoura land will be restored.

Now if you think about this for a second you will realize that trying to bend a thin plate of steel hardened to Rc65~66 without snapping it is a fool’s errand. In the case of Japanese blades it is possible to accomplish but only because of the thicker, cushioning layer of soft low-carbon/no-carbon iron, called the “jigane,” to which the hard steel layer is laminated.

Your humble servant struggled at first with uradashi, in part because every explanation I read about the process in both English and Japanese was written by people who either didn’t really know what they were talking about, or were too lazy to explain it well. Some years, several broken blades, and much heartbreak later I finally figured it out. Better information is available nowadays, but there is still plenty of BS out there to shovel.

The first key point to understand and always remember is that uradashi is not about using a hammer to bend the hard steel layer; Never ever ever never touch this steel with your hammer.

Instead, the goal is to peck on the soft iron jigane layer of the laminated blade, as described below, expanding it so the hard steel layer laminated to it will curve in the direction of the ura without snapping or cracking. Please read the previous three sentences again, offer a prayer of remembrance to the gods of handsaws, and click your heels three times (ruby slippers are not mandatory(ツ)).

The second key point you need to grasp around the neck with both hands and dig your Jimmy Choos deep into is that it is indeed a fool’s errand to try to bend the soft iron lamination by the power of your mighty arm, Oh Lord of Thunder. No, we must be as clever as Loki.

So, how do we cleverly do this job, and what tools should we use?

The 60mm blade used in this example forged by Mr. Uchihashi Keisuke from Swedish K-120 steel. The brand name is “Keisaburo.” An excellent blade and still functional, but the itoura is getting a little skinny.

Tools

You will need the following tools to properly perform uradashi and uraoshi on a blade:

  1. A small hammer. Great force is neither necessary nor useful, but you must be able to control this hammer very precisely, so the lighter the better. One with a pointy end like a funate or a Yamakichi or the corner of the thin end of a Warrington hammer is ideal because it focuses maximum pressure on a small area, deforming the jigane efficiently, and it is also easy to see where the hammer will impact providing better control. And control matters a lot because if you miss and strike the hard steel at the cutting edge it will be damaged and bitter tears will flow. Consider yourself duly warned, Oh Might Thor;
  2. An anvil of sorts. This can be any piece of steel with some mass and with a rounded-over corner. A piece of railroad track is great. I use the face of a small sledge-hammer clamped in my vise. A sharp corner is not good, so grind or file one and then smooth it. A piece of thin postcard material glued to this rounded corner help keeps the blade from slipping;
  3. A small square or straightedge;
  4. A marking pen or scribe to mark the “target area” on the bevel;
  5. A rough diamond plate or a mild-steel kanaban plate + carborundum powder;
  6. Parking pen or Dykem for coloring the ura’s lands;
  7. Regular sharpening tools (stones, etc.);
  8. Water.
A small sledge hammer used as an anvil by clamping it in a vise with another clamp as a stabilizer.

Target Area Layout

Let’s begin by laying out the target area on the soft iron jigane at the blade’s bevel with a marking pen. Or you can scratch lines into the jigane with a metal scribe. This target area will indicate the area you will peck with your little hammer producing many small dents. You must not strike outside this target area even if tempted with donuts.

The striking area marked with marking pen.

The dents you will make with your little hammer need to be limited to a band on the jigane parallel to the cutting edge and beginning 2~3mm from where the jigane lamination begins extending to the end of the jigane lamination at the blade’s back, in the case of plane blades, or the face where the brandname is engraved in the case of chisel blades. Make a line with your scribe or marking pen the full width of the bevel at this distance from and parallel to the cutting edge. Everything above this line in the direction of the blade’s back, in the case of plane blades, or the face where the brandname is engraved in the case of chisels and knives, is the primary target area. Make sure you get this right.

The dents need to extend across the full width of the jigane layer, except where the corners (ears) have been ground to a bevel at the right and left end of the blade, so the right and left limits of the target area are delineated by the ears.

Although we need to tap the full width of the blade to avoid stress concentrations, there is nothing to be gained by trying to bend the far right and left corners of the blade, so we want to focus approximately 2/3rds of our hammer impacts and the resulting dents near the center 1/3 of the blade’s width. Mark the right and left limits of this central area on your blade with a marking pen or scribe.

The Grip

If you are right handed, hold the blade in your left hand with your index finger extended and pressed against the ura parallel with the cutting edge, and about 5~10mm away from it. Press down with your thumb on the blade’s back clamping the blade between your thumb and the side of your index finger. Your other fingers should support the blade from the ura side.

This shows how to hold the blade on the anvil.

Your index finger will be the fence that keeps the blade in proper alignment during the tapping-out process.

Next, we need to figure out how to align and move the blade on the anvil, as well as where to place hammer blows in relation to the blade and anvil.

This photo shows the grip without the blade in the way. Notice how the index finger is touching the anvil. The blade is shifted right and left using the index finger as a fence to keep blade and hammer under tight control.

Manipulating the Blade on the Anvil

Place the blade’s ura on the rounded corner of your anvil. You may want to tape or glue a piece of thin cardboard, postcard, or manila file folder to the anvil’s corner not so much as a cushion but to help prevent the blade from slipping, but this is not mandatory.

Adjust the distance between your extended index finger and the cutting edge as necessary so your finger is touching the anvil stabilizing its position, and so you can slide the blade to the left and right indexing off your finger to keep the target area in proper alignment.

Next, while still in position facing your anvil and with hammer in hand, move the blade aside and tap the rounded corner of your anvil with your hammer lightly. Memorize this location and your position because every tap from now on must be aimed at this same exact spot on the anvil.

The Tap Dance

The time has come to begin the dance.

Reposition the blade on the anvil and use your little hammer to tap the soft jigane layer at the bevel (only the jigane!) in the target area you marked earlier making a row of small dents in it.

These small dents don’t need to be pretty or uniform. Be patient because you may need to make hundreds of pecks, each one quite precisely.

Here is the key point to understand: You want each little dent to cause the jigane to deform and expand in length and width a tiny bit, gradually, until a significant degree of deformation accumulates. The hard steel layer, however, will constrain the jigane layer from expanding, causing the blade to bend, and causing the hard steel layer to deflect and curve towards the ura, bending it without breaking it. It doesn’t seem possible at first, but I promise it will happen, so please be patient.

The trick then is to use the grip described above and use your forefinger to index the blade against the anvil while moving your hand, along with the blade, a tiny bit right or left with each strike, with the each point of impact firmly supported on the anvil, in-line with the hammer blow, thereby squishing the jigane between hammer and anvil. In this way, since the hammer is always aimed at the same exact point on the anvil, you don’t need to worry about realigning it with each blow, removing several difficult-to-control variables from the tap dance at once.

Remember, keep the hammer and anvil precisely aligned, and move the blade left and right, not the hammer. It helps to touch the inside of the elbow of the arm using the hammer against your side in a fixed location to help maintain a consistent hammer swing and distance. Until you have mastered consistency, speed is risky.

Another key point to understand is that, unless the point of your little hammer’s impact is not directly in-line with the point where the ura on the opposite side of the blade is touching the anvil, the force of the hammer’s impact will tend to cause the unstable blade to jump and wiggle around instead of deforming the jigane. This wastes time and energy and makes it difficult to make precise taps.

Here’s a video of Eleanor Powell tapping away with great control, and with the aid of her faithful Fido. I don’t recommend including a benchdog in your tapping-out routine other than as a deterrent to any pernicious pixies lurking in your workshop eager to cause you to miss with your hammer and chip your blade. Evil pixies!

Here’s a video of Sarah Reich tap dancing with every strike landing precisely in the target area. I need to get a pair of shiny red lycra pants like her to go with my most excellent aluminum foil hat with the curly copper wires and red fringe. Do you think they would make my butt look huge?

Remember, force is neither necessary nor useful. The goals is to make many precisely aligned tiny taps producing many small deformations in the target area, with no impacts on the hard steel layer.

Dent Removal

We talked about “dents” above. If you are using a round-faced hammer, those dents will be little crescents. If you use a hammer with a tiny striking face on one end like a Yamakichi or Funate, that tiny face will dig into the metal making ugly little peck marks instead of pretty little crescents. I have used all varieties of hammers but prefer the ones with pointy ends because they impact face is small and, it seems to me, easier to control. Six of one half-dozen of the other.

But remember that we will abrade away all those dents/craters after a few sharpening sessions, so appearance is of zero importance.

The Goldilocks Itoura

The goal, of course, is to bend the blade at the ura land just behind the cutting edge enough to create a useful, flat ura. But how wide should the itoura be when the process is complete? Among plane connoisseurs a narrow itoura is, like a willowy super model, considered a thing of beauty. By narrow I mean some where around 0.50~1.0mm.

A narrow itoura does indeed look sexy, so much so that fashion-conscious plane blade blacksmiths make a skinny ura a point of pride. And, in fact, a bulimic itoura makes it easier and quicker to sharpen the blade because the square millimeters of hard steel one must abrade/polish is minimal compared to a wider itoura.

The downside to the super-model itoura is that it wears out sooner, making it high maintenance. Now, I’m not suggesting that if your plane blade has a super-skinny itoura it will demand weekly spa visits, twice monthly trips on a G700 jet to the Vienna Opera, annual ski holidays in Verbier, and bi-annual boob jobs, but there is no doubt you will need to do the uradashi tap-dance more often. Shiny lycra pants are optional, but ooh sooo sexy.

On the other hand, a wider itoura of 3~4mm has some advantages too. It’s easier to fit the chipbreaker (uragane), and you don’t need to do uradashi/uraoshi as often. Much wider than this, however, and I find it can be difficult to get a screaming-sharp edge at times. Moderation in all things, I guess.

I don’t know how to describe when to stop tapping-out the ura to obtain a good width for your itorura because every blade is a little different, but after doing it a few times you will develop a sense of when enough is enough. However, to develop that sense you should make frequent checks on your tapping-out progress by placing your handy dandy straightedge or square right on the itoura parallel to the cutting edge and sighting between the blade and the straightedge/square with a strong light shining at the gap. You will be able to see the itoura gradually bulge upwards at the center. Even a little bit of a bulge will give you a useful itoura, so don’t get carried away.

Uraoishi

Once the tap dance is done, we need to grind down the ura to form a new itoura.

The traditional method is to use the mild steel kanaban lapping plate mentioned above, although any true lapping plate will work. One sprinkles a small amount of carborundum powder on the plate along with a little water, and works the ura side to side grinding down the bulged area to make a flat.

The problem with lapping plates and carborundum powder is that not only is it a messy process, but unless you are careful to keep the right amount of wet grit on the plate, the results tend to be a tad irregular. I recommend using diamond plates because they produce more consistent results quicker.

Whether you use a kanaban lapping plate or a diamond plate, it is important to focus pressure on the thin area where you need the itoura to develop. Pressure anywhere else is not helpful, but only wears out the itoura prematurely.

Here is wisdom: When they first attempt uraoshi most people try to stabilize the blade by applying uniform pressure across the back of the blade. This seems to makes perfect sense, but it always results in grinding a nasty little trench in the ura where it touches the extreme edge of the kanaban or diamond plate. Remember, the uraoshi process tapped out a bit of metal right at the cutting edge, and mostly at its center. This is what you need to abrade, NOT the right and left lands of the ura, and certainly no more than 3~4mm from the cutting edge. So carefully focus the pressure you apply during uraoshi only on the thin area where you need to restore the uraoshi.

Some people like to apply a thin strip of paste wax, perhaps 3~4mm wide, on the edge of their kanaban or diamond plate to prevent it from digging ugly trenches in their beautiful and delicate side lands. Others like to apply a thin strip of mylar tape at the same place for the same reason. These techniques all work, but professional sharpeners don’t use them because they know how to apply pressure correctly.

A quick touch of the blade on the diamond plate shows where the black marking pen ink has been removed, and the highest spots on the bent itoura.

After the itoura has been restored (perfection is not necessary), polish the blade using your normal sharpening routine.

The restored itoura.

The bevel after working it on the diamond plate and stones. The remaining peck marks will disappear entirely after a few sharpening sessions.

Chisel Blades Versus Plane Blades

Uraoshi and uradashi are operations typically, but not exclusively, performed on plane blades. About the only time chisels need to have uradashi performed is to restore the itoura after the blade receives major damage, like a big chip. A sad event all users of Japanese tools experience from time to time

There is a structural difference between plane blades and chisel blades one must understand when considering performing uradashi on a chisel blade.

Plane blades have a steel lamination that is more-or-less uniform in thickness because that’s all that’s necessary. Chisel blades, on the other hand, are subject to much higher bending stresses than plane blades, so to prevent yielding and failure, traditional chisels are forge-laminated with the steel lamination wrapped up the right and left sides of the blade, forming something akin to a structural steel U-channel, producing a higher moment of inertia, and therefore greater strength and rigidity,

Because of this additional strength, chisel blades are more difficult to bend at the right and left sides using uradashi techniques compared to plane blades. Indeed, they may break if you try.

Since you can only hope to safely bend the steel lamination in areas away from the more rigid sides, uradashi operations on narrow chisel blades will go as smoothly as throwing a cat through a screen door. I wouldn’t even try it on any chisel narrower than 24mm. Beloved Customers have been warned.

If you feel compelled to attempt uradashi on a chisel blade, my only advice is don’t peck within 3mm of the right and left sides.

With this article, our Sharpening Japanese Tools Series is complete (probably). I hope it has been helpful. If you’ve had the patience to read it all, and the clairvoyant ability needed to understand most of it, then you know a heck of a lot more on the subject of sharpening than I did when I started the journey. At least you have received some great ideas for sexy new additions to your simply mahvelous woodworking wardrobe!

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 Iron Pixies pass gas in my cornflakes every morning.

Links to Other Posts in the “Sharpening” Series

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

Japanese Handplanes Part 2 : Blade Adjustment

I warn you, if you bore me, I shall take my revenge.

J.R.R. Tolkein

Your most humble and obedient servant has received many requests over the years for explanations about how to setup, adjust, maintain and use Japanese planes. It’s a big subject, enough to fill volumes and volumes, and an important one to woodworkers, but I will try to explain in enough generality that new guys can follow, and in enough detail that professionals may glean something useful.

In this series we will discuss how to adjust a Japanese plane so it works well, how to tune it to increase performance, how to treat the body to reduce warpage and keep it looking good, how to deal with normal wear and tear, how to periodically tap out and dress the ura during sharpening, and of course how to use a Japanese plane.

This last subject is extremely simple but one many amateur users of Japanese planes and most users overseas get wrong. It happens so frequently that I am confident the improvement in Beloved Customer’s personal performance with Japanese planes will improve dramatically from this last subject alone.

The problem with Japanese planes is that, while they are simple tools, they are at the same time more sophisticated than appearances suggests. Dealing with these subtle details without properly understanding them leaves many as confused as a ball of yarn among a dozen big-eyed kittens, so to avoid having too many strands running all over the place, let’s start with the basics, namely how to adjust them. For purposes of this discussion, we will assume our plane is in good fettle to begin with.

Terminology

Your humble servant will not attempt to teach Gentle Readers all the Japanese terms for every part of the hiraganna plane but will try to use standard English language terms wherever possible instead. Indeed, since the plane is a relatively recent tool in the Japanese woodworker’s toolbox, and has a much longer archeological history in the West, it seems silly to use more Japanese words than absolutely necessary to describe something that did not originate in Japan, and can easily be described in English.

I am not a government employee or a legal expert, and so see no need to make things more confusing than necessary. I humbly apologize in advance if this approach offends any purists or employees of the IRS.

The standard handplane in Japan, the one intended to create and/or smooth flat surfaces versus rabbet, chamfer or molding planes, just to name a few, is called the Hiraganna. This word is written 平鉋 in Chinese ideograms and pronounced hee/rah/gahn/nah, without emphasis on any part of the word.

The first character 平 means “flat.”

The second character 鉋 is comprised of two standalone characters combined to make a single character, a common practice in the Japanese language. The one on the left side, 金, means gold or metal, while the one on the right, 包 means “to wrap.”

The character for kanna was not invented in Japan but is said to have been used since the Táng period AD618 – 907 in China, although the tool it represented at the time was a scraper of sorts and not a handplane.

Preparing the Body

Although this is not an issue in the case of the planes C&S Tools purveys, Gentle Readers will want to inspect their plane, and perhaps make a few modifications to the body before playing with the blade too much.

Striking Chamfer

When removing the blade or reducing the cutting edge’s projection through the mouth, we need to strike the body on the corner between the flat end of the plane’s body and its top surface, so we need a chamfer at an approximately 90˚ angle to prevent damage to the body. How wide? 3~5mm is a good range. While you are at it, cut off the corners formed at the right and left sides of this chamfer.

This is a one-time operation.

Sole Chamfers

You need a chamfer on the right and left sides (long direction) of your plane’s sole.

These chamfers have two purposes. First, to prevent the edges of the sole from chipping. Second, to make a gap for your fingers to grip when lifting up the plane.

As the sole wears, Beloved Customers and Gentle Readers will need to be refresh these chamfers from time to time, so further explanation is necessary.

Some people promote big, wide 45˚ chamfers at these locations. Your humble servant has even seen country bumpkins cut these wide chamfers and then cut grooves leading from the sides of the mouth to these chamfers for shavings to escape into. Codswallop!

The thinnest, weakest portion of any wooden plane’s body is sidewalls at the mouth. This is also where most warpage originates, so please don’t weaken it more than is absolutely necessary. In addition, wood removed from the sole by cutting overly-large chamfers reduces the bearing area of wood on the surface being planed accelerating wear on the sole. Keep these chamfers narrow at 3~5mm and a max angle measured from the sole of 25~29˚ More than this is unnecessary and possibly harmful.

A chamfer is not necessary at the trailing end of the sole so long as you have the self control to not strike the sole with your mallet.

Do not cut a chamfer at the leading edge of the sole as it will guide sawdust and shavings between the sole and the surface you are planing.

Top Chamfers

Apply a small chamfer on the front and side edges of the top surface, just enough to prevent chipping. 45˚ chamfers are fine, but a roundover (bozumen 坊主面 which translates to “Priest’s edge,” probably in reference to the bald head of Buddhist priests in Japan) is a friendlier, more elegant edge treatment, IMHO. Your choice.

Hammer or Mallet

In order to use a plane of any kind, one must remove the blade to sharpen it, and then re-install the blade and adjust its projection from the body’s mouth to produce a wood shaving of the desired thickness.

Like most wooden-bodied planes, one adjusts a Japanese plane by striking it with a hammer or mallet. To drive the blade further into the wooden body (called a “dai” 台 in Japanese) when installing the blade or when increasing the depth of cut, one taps the head of the blade down into the wooden body. Pretty straightforward. But like most things in life, there are both clever and stupid ways to get even simple jobs done. Let’s consider some of the clever ones, shall we?

The wacky ones can be very entertaining, I know, but I think I’ll leave those for the tool abusers on GooberTube.

You can use either a metallic hammer or a mallet made of wood, plastic or even rawhide to tap the blade or dai during these operations. They all work just fine, but there are long-term consequences to this selection you need to be aware of.

In Japan a steel hammer is traditionally used by carpenters to adjust planes. Without a doubt it’s convenient and effective, but there are some serious downsides to using a steel hammer you may not realize. Those include:

  1. A steel hammer always mushrooms the blade’s head;
  2. A steel hammer always dings the blade’s pretty face, and most critically;
  3. After many strikes, steel hammers will often crack and even split the wooden body (dai).

A deformed and ugly blade may not be a tragedy, but a split body is an expensive and time-wasting catastrophe, especially if you are a professional that needs his planes to keep cutting.

What did this brightly-polished plane blade do to deserve such barbaric abuse?
All the worst consequences of using a steel hammer on a plane are condensed in this one photo. Notice the mushroomed head of the plane which the owner has probably already ground down several times. We can’t see the blade’s face, but notice how the chipbreaker’s face is all dinged up. And I guarantee you the blade is even more damaged. And of course, the split dai. Tragic! What did this poor innocent little plane do to deserve such barbaric treatment?! And how much of this plane’s useful life did the owner waste?

There may be Gentle Readers who will say: “But I’ve seen Japanese craftsmen using steel hammers to adjust their planes, so it can’t be wrong.” The first part of this observation may be true, but the last bit isn’t. The undeniable truth is that steel hammers have created many ugly, dinged, bent, and mushroomed blades, as well cracked and splintered dai, mostly unnecessarily. Some carpenters are especially abusive of their poor planes, sorry to say, but not all Japanese craftsmen are so inured to the suffering of their tools.

C&S Tool’s planes don’t deserve such violent abuse, so we recommend Beloved Customers use a wooden mallet to adjust them. Without exception. A plastic or rawhide mallet with a wooden handle will work just as well.

Removing the Blade and Chipbreaker

Both the blade and chipbreaker are removed by tapping the chamfered corner of the block behind the blade with a mallet. We discussed this chamfer above.

It is of course possible to loosen the blades by tapping the flat tail end of the block, but there is a risk of striking the bottom edge and deforming the sole. Best avoided altogether.

The physics work best when the mallet impacts are applied in a direction more or less parallel with the blade.

Your humble servant prefers to make this striking chamfer wide to minimize deformation of the body, but this is a personal preference. If your plane’s body is not chamfered, creating it is is an important first step.

The chipbreaker (uragane) must be removed before the blade, but you need to be careful to prevent two unfortunate things from occurring during this process. The first thing to avoid is the chipbreaker jumping out of the block providing Murphy the opportunity for gleeful mischief.

The second thing to avoid is the blade backing out of the body further/faster than the chipbreaker causing the chipbreaker to ride over the extreme cutting edge dulling it. This point is one newbies often overlook until they wonder why the pretty cutting edge they just sharpened is dinged even before they begin cutting.

How does one keep blade and chipbreaker under control? Your humble servant recommends pressing a forefinger onto the chipbreaker and applying pressure upwards when removing it. Do the same on the face of the blade when its turn comes/ as shown in the photos below.

When removing the chipbreaker, apply pressure towards the blade and upwards with your index finger to monitor its movement and help maintain control. It is critical that the chipbreaker moves upward faster the than the blade to prevent the chipbreaker from contacting the sharp cutting edge dinging it.
While applying upward pressure with the index finger on the chipbreaker, tap the chamfer behind the blade to cause the chipbreaker to move up and out of the body’s mouth. BTW, please make it a habit to not strike the center of the chamfer, but instead alternate strikes between the right and left sides of the chamfer to ensure the body will provide long service.

Once the chipbreaker is loose, remove it and go back to tapping the body to loosen the blade further. Continue to apply light pressure to the blade’s face to better monitor the blade’s movement, and to prevent it from jumping out of the body.

The plane used for this example is an extra-wide 80mm finish plane with a blade forged by Yokosaka Masato. The oasaebo steel rod which retains the chipbreaker in-use can be seen tightly installed across the mouth. This is typically never removed over the life of the plane. In the center are the blade and the chipbreaker (uragane). A very nice blade hand-forged from Shirogami No.1 high-carbon steel. To the right is the mallet your humble servant uses for plane adjustments. Notice how the head of the blade is not mushroomed, its pretty face is free of the dents and dings, and the body is free of the dents, cracks and splits that often result from using steel hammers.

Adjusting the Chipbreaker (Uragane)

The chipbreaker is a recent addition to the Japanese plane. In earlier centuries, they had only a single-blade. Unlike the Western Bailey-pattern planes that incorporate the chipbreaker into the linkage necessary to adjust the blade, hiraganna planes work just fine without the chipbreaker. Indeed the chipbreaker’s only role is to reduce tearout, so when tearout is not a concern, removing the chipbreaker will reduce the force necessary to motivate the plane and may even produce a smoother cut.

The chipbreaker of a new plane often needs to be fitted to the blade and body using files and stones, but that is a subject for a future article, so to keep things simple, we will assume the chipbreaker is in good shape and is happily wedded and bedded to its blade.

Gentle Reader is no doubt wondering how to adjust the chipbreaker with the large head of a mallet. The answer is to use the butt of the handle as shown in the photo below. Just hold the mallet’s handle in a fist with the head upward and bring the handle’s butt down on the the chipbreaker. Easy as falling off a log, as my father would say. The connection between the mallet’s head and handle must be quite solid, of course. These mallets are easily made.

Using this technique, your plane blades will look beautiful, and your dai will give many years of reliable service. And although they only have tiny mouths with just a single, shiny, silver tooth, if you look carefully you will sometimes see their clever little smiles.

Using the end of the mallet’s handle to adjust the chipbreaker. Notice that, once again, the index finger is use to monitor the chipbreaker’s movement and to keep it under careful control. To ensure the chipbreaker will do its job, its edge should ultimately be adjusted to be in very close proximity to the cutting edge (>0.002″ (0.05mm). This distance will vary with your plane and the wood being cut, and will require experimentation and fiddling to get right, but with practice, this process will become automatic and intuitive. Be careful to prevent the chipbreaker passing over the cutting edge as this may dull the blade causing Gentle Reader to say undignified things and the iron pixies skulking in your workplace to howl with glee.

To remove or back-out the chipbreaker, one strikes the dai as if loosening the blade, but with a finger on the chipbreaker to keep it from dragging over and perhaps dulling the blade’s cutting edge.

When adjusting the chipbreaker, sometimes the blade will shift position too, so a back and forth adjustment of blade-chipbreaker-blade is sometimes necessary. The tighter the fit of the blade and chipbreaker in the body, the more fiddling is required, so craftsmen such as joiners, sashimonoshi and cabinetmakers that routinely make fine, precise cuts and sharpen frequently tend to prefer thinner blades that fit into the body with less force and are easier to adjust than do carpenters who perform less refined work.

We will delve into this aspect of handplane setup in our journey ass over teakettle down the rabbit hole in a future post.

Adjusting the Blade

In order to take a clean full-width cut, the blade must project from the mouth the appropriate amount, and evenly across its width. In other words, it must not project too far, nor too little, and one corner of the blade must not be projecting more than the opposite corner.

To evaluate the blade’s projection through the plane’s mouth, hold the plane upside down to a light-colored uniform background and look along the plane’s sole. The correct projection will be a thin line of uniform height across the width of the sole. If one side of the blade is projecting more than the opposite side, the blade is either skewed in the body, or it is shaped skewed.

If the blade is skewed, tap the head to the right or left with the mallet. If, however, a few taps fails to make the projection uniform, the blade’s cutting edge must be reshaped.

Please be aware that continued lateral pounding on the blade will not improve the situation and may damage the wooden body.

Most planes allow a little bit of wiggle room for the blade, but sometimes, especially if the body shrinks in width due to reduced ambient humidity, the notches in the side of the mouth may need to be pared slightly deeper, or the blade ground narrower, to provide this right/left wiggle space. Be very careful, however, to avoid paring these grooves more than a thin shaving or two wider because removing wood at the grooves directly and irrevocably weakens the weakest point in the wooden body.

Looking down the sole to ascertain the blade’s projection, the black line visible at the top of this photo. A light-colored, uniform background is helpful for this. In this case, two adjustments are necessary. The first problem is that the blade is projecting too far. This is easily resolved by tapping the chamfer behind the blade, something that, with practice, can be done while the plane is held upside-down in this position. The second problem that must be resolved is the skew evidenced by the blade’s projection being much greater on the left side of the photograph.
Adjusting a skewed blade by tapping the blade’s head laterally. If a few taps will not correct a skewed blade, it probably needs to be reshaped to correct a skew that developed during sharpening.
A much smaller, useful projection with just a tiny bit of residual skew that must be corrected. When taking extremely fine finish cuts, the ability to determine the blade’s projection sometime seems more clairvoyant than simply optical.

To test the projection of the blade, and ensure skew has been removed, hold a a short, narrow piece of softwood such as pine or cedar in your hand and run it over the cutting edge, first on one side of the blade, then the opposite side, and finally the center, and observe the shavings (if any) produced. They will tell you the truth. Be careful not to shave your fingers unless they have become hairy (ツ).

Even experienced craftsmen betimes become gutted, gobsmacked, and guragura upon discovering their otherwise perfect plane blade has become skewed and is projecting too far on one side to be adjusted for a good cut without resharpening it. Of course, the culprit is almost always pernicious pixies, but a wise Beloved Customer (are there any other kind? Nah!) will be careful to follow Petruchio’s example and tame the skew. And don’t forget to use a hardened stainless steel straightedge to check the blade for square when sharpening.

Striking the Body of the Plane

Your humble servant does not want to seem repetitious, but just so there is no confusion, I feel compelled to review a point or two before we end this discussion.

When backing out or removing the blade, make it a habit to strike the chamfered edge of the dai behind the blade alternating between the right and left sides instead of dead-center.

Also, angle your strikes so they are more or less parallel to the long axis of the blade. With a little practice this will become second nature. The reason for this action is simply that it is both more effective and at the same time helps to keep the dai in one piece.

Please, never strike the flat tail end of the plane’s body, but only the chamfered top edge of behind the blade. Too many people who strike the flat end of the tail get carried away and end up damaging the sole.

If you examine your plane you will notice that there is actually very little wood holding the plane’s body together in the mouth area. Indeed the only continuous wood is at the sides, and it is only as thick as the distance between the bottom of the blade grooves and the exterior sides of the body. Not a lot of meat.

If we strike the body’s tail in the center, the body, being relatively unsupported in this area, must flex creating stresses, sometimes enough to crack, sometimes even enough to split it. This sort of damage is common, but almost entirely avoidable because, if we strike the right and left extremes of chamfered edge behind the blade, stresses will be carried through the stronger sides reducing the chances of cracking and/or splitting the tail. You can feel and even hear the difference if you pay attention.

If you don’t care how your plane looks, and prefer replacing or fixing their wooden bodies instead of using them, by all means disregard this suggestion. You might want to get some extra bubble wrap to keep yourself entertained while the bolt and epoxy repair to your plane’s broken body cures.

Damage to the body or blades of C&S Tool’s planes caused by the incorrect use of metal hammers will void the tool’s warranty.

Plane Storage

When you purchase a plane, the blade is already installed in the body, although the cutting edge is usually recessed inside the mouth to protect it. The first step, therefore, is to remove the blade and examine it.

If you live in a low humidity area such as Nevada or Arizona in the USA and purchase a plane from a part of the world with high-humidity at times, such as Japan, it is wise to remove the blade and set the plane aside for a few days to let the body become acclimatized, especially if you plan to use the plane in a space with central heating and cooling which may cause the wooden body to shrink in width

If you plan to store your plane for several years in a dry climate, or in a space with central heating and cooling, we recommend you remove the blade and chipbreaker, oil them, wrap them in aluminum foil, and store the body and blades together but without being installed in the body to prevent the blades from restraining the body’s shrinkage causing it to crack. Just to be safe.

In the next post in this adventure we will discuss how to modify a Japanese plane’s body to make it easier to use.

And please remember the wise words of the Sage of Possum Lake: “Remember I’m pullin’ for ya–we’re all in this together.”

YMHOS

The end view of an amazing nagadai plane body by Inomoto-san made from a piece of Japanese White Oak combining “Oimasa” grain orientation and the highly-desireable ripple grain. In oimasa orientation, the dense, tough, light-colored medullary rays are oriented towards the sole, making the sole wear slower. Using plain-sawn wood will direct even more of these rays to intersect the sole further reducing wear, but at the same time would increase the tendency of the sole to warp. On the other hand, orienting the annual rings vertically in a “quartersawn” configuration would maximize the body’s stability, but at the same time would cause the sole to wear quicker while making the body less resistant to cracking and splitting. Oimasa orinetation shown in this photo is a compromise intended to reduce warping without reducing strength and to improve the sole’s wear resistance. Ripple-grain white oak is not only more beautiful, it contains more of the harder Winter wood making it both more wear-resistant and more stable than ordinary white oak.

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 plane blade be forever skewed if I lie.

Other Posts in the Japanese Handplane Series:

Four Habits and Three Mysteries

The carpenter dresses his plank, the tongue of his foreplane whistles its wild ascending lisp

Walt Whitman, “Song of Myself,” Leaves of Grass

When working in wood the professional aiming for efficiency must continue the work of accurately cutting or shaving wood just as long as possible without stopping to sharpen his blades too frequently because time spent sharpening is time the primary job isn’t getting done. The wise professional therefore needs chisels, planes and knives with cutting edges that not only become very sharp and cut exceptionally well, but stay sharp a long time. C&S Tools are handmade one at a time by master blacksmiths to meet the expectations of Japanese professional woodworkers for sharpness and edge retention.

Alas, even our tools do not have eternally-sharp cutting edges, and at some point must be resharpened to maintain work efficiency and product quality. The experienced professional craftsman will develop unconscious habits to help him constantly monitor the condition of his blades and the quality of the work being performed. In this post we will examine a few ancient techniques for doing so.

The Four Habits

As the saying goes, “timing is everything.”

If Beloved Customer pays attention, you will discover there is a point where a woodworking tool’s blade still cuts, but its cutting performance begins to drop off. Sensing this point in time is critical because if you continue cutting wood much past this point, not only will the energy needed to motivate the blade increase dramatically, but the quality of the cutting done will quickly deteriorate while the time and stone expenditure necessary to resharpen the blade will increase. That’s three variables in the blade, the work and the craftsman that could be expressed in a pretty graph if one was so inclined, a graph that would have at least one inflection point. Which variable is most important to you?

In most cases, when considered from the viewpoint of a craftsman that uses and sharpens his tools daily, and needs them to be quite sharp, minimizing wasted of time and stones over the years tends to be the governing variable because it costs the most money.

Most woodworkers fail to consider these efficiency variables; They simply keep cutting away until the tool either becomes too difficult to motivate, or it stops doing an acceptable job, then stop work and sharpen the blade. This is normal, but the wise woodworker will focus on minimizing the total time and total cost required to maintain his tools even if it means he must pause work to resharpen his blade well before its performance deteriorates badly.

This sharpening inflection point will vary from blade to blade and job to job because every blade, every piece of wood and and every user are unique. Simply counting strokes is not enough. It takes attention and practice to sense when a blade has reached this point.

The following are some things you should pay attention to, and habits you should develop, to help you identify the sharpening inflection point.

Habit No. 1: Sense Resistance Forces: As you use a tool, a plane, chisel, or saw for instance, tune your senses to detect the point at which the blade becomes more difficult to motivate. As the blade dulls, the force that you must apply to the tool to keep it cutting will gradually increase. This is especially noticeable when planing and sawing. Develop the habit of paying attention to this force so you can determine when it is time to resharpen. Your humble servant recommends you regularly use an oilpot to ensure any increased resistance is due to a dulled blade and not increased friction between the tool and the wood;

Habit No.2: Listen to the Music: Pay attention to the tool’s song. That’s right, turn off the radio and CD player and listen to the music your blades make instead. If you do, you will notice that each tool sings its own song, one that varies with the wood, the cut, and the condition of the blade. Is the blade singing, lisping, or croaking as it chews wood? Is it a saw with a basso profundo voice, or a mortise chisel with vibrant tenor tones, or perhaps a soprano finishing plane singing a woody aria? A sharp blade makes a clearer, happier sound when cutting or shaving wood than a dull one does. Learn the happy song it sings when it’s sharp and the sad noise it makes when it’s dull, and all the changing tones in between. If you have ears to hear, it will tell you what kind of job it is doing and when the time has come to resharpen it;

Habit No.3: Eyeball Cuts: Watch the tool and the wood it has cut. Is your chisel cutting cleanly, or is it crushing the wood cells? A sharp chisel blade cuts cleaner than a dull one. You can feel and hear the difference. And you can see the difference in both the shavings or chips and the surfaces the tool leaves behind. Don’t be a wood butcher: develop the habit of frequently checking the quality of your cuts. It doesn’t take extra time, and your tools will wiggle with happiness;

Habit No. 4: Feel Surface of the Wood: Is your plane shaving the wood cleanly, or are the surfaces it leaves behind rough with tearout? Develop the habit of running your fingers along the path your plane just cut to sense surface quality. If you detect roughness or tearout, the plane may be out of adjustment, or more likely, the blade is becoming dull. Or maybe you need to skew the blade, change the direction of the cut, or moisten the wood’s surface with a rag dampened with planing fluid (I use water, industrial-grade busthead whiskey, or unicorn wee wee when I can get it). Next, run your hand across the cut your plane just made to detect ridges that may have been created by irregularities or chips in your blade’s cutting edge. Every one of those ridges indicates a small waste of your time and energy and a flaw in the wood. Don’t forget that the top of those ridges contain compressed cells (kigoroshi) that may swell and become even more pronounced with time. This is accomplished with a few swipes of the fingertips along and across the wood between cuts without spending any time.

These techniques are not rocket surgery. They don’t take extra time. They can be applied to any tool all the time. The key is to pay attention. To listen to one’s tools. To watch their work.

Let’s next shift our attention to three of the Mysteries of Woodworking, their potential impacts on mental health, and how to avoid unfashionable wardrobe decisions.

The Mystery of the Tilting Board

To discuss this Mystery, we will call on the services of my old buddy Richard W. (Woody) Woodward. You may remember him from a mystery story in previous article. Yes, it was a near thing, but he has fully recovered from the effects of chugging a 5th of tequila in an emotionally-charged bout of drama over a brittle blade.

Anyway, this mystery goes something like this. Woody is planing a board about the same width as his plane’s blade down to a specific thickness, but for some unfathomable reason, the board ends up thinner on one side of its width than the other. He checks the blade’s projection from the plane’s mouth, but it is absolutely uniform. In fact to make the board the correct thickness he ends up having to tilt the blade to take less of a cut on one side of the board than the other.

Most everyone has experienced this curious and wasteful phenomenon, but because it is not consistent, many never solve the mystery of the tilting board, but blame it on Murphy’s antics or Pixie play. But never fear, because the solution is elementary, Dear Watson.

In Habit No. Four listed above, your humble servant mentioned residual “ridges.” Please be aware that these ridges are not only unsightly and may damage applied finishes later, but they can actually keep your plane from cutting shavings of uniform thickness. Think about it.

Let’s assume you are planing a board the same width as your plane blade, but the blade has a tiny chip near the right end of the blade that leaves behind a .0005″ high ridge on the board’s surface. With each subsequent cut using this same blade with the same defect the right side of the plane’s body and likewise its blade will be elevated above the board’s surface by .0005″, while the left hand side, which doesn’t have any ridges for the plane’s sole to ride on, is shaved the normal amount.

Assuming you checked that the blade is projecting from the plane’s mouth the same distance across its entire width, with each pass the surface of the wood becomes tilted, a little high on the right side and a little low on the left, so that instead of a flat surface square to the board’s sides, you have produced a flat surface that is thinner on the left side and thicker on the right. This is no bueno, amigo.

If you detect ridges on a freshly-planed surface, immediately check the blade’s cutting edge by running a fingernail along it’s width. Don’t worry, it won’t dull the blade unless you are also a bricklayer. Your nail will feel the catch and grab of defects too small for your eye to see. A few small ones may make no difference, but on the other hand, they might make a big difference.

With this the Mystery of the Tilting Board, one that has driven many a woodworker to distraction, sometimes even leading to fashion decisions involving stiff, canvas jackets with long sleeves connected to straps and buckles that fasten behind the barking woodworker’s back and even pass under the crotch (decidedly uncomfortable, I assure you), has been solved. Only the Beloved Customers and Gentle Readers of the C&S Tools’s Blog can be assured of avoiding this undignified state. Sadly, all others must be responsible for their own mental health.

The Mystery of the Missing Plan

Here is another mystery of woodworking, one that especially vexes those tender souls new to the calorie-burning fun of dimensioning wood by hand.

Let’s say Woody needs to turn a bunch of twisty, banana-shaped boards into flat, square, precisely dimensioned and cleanly-surfaced drawer fronts, for example. All the adjectives after “banana” in the previous sentence are critical to his project’s success because Woody’s ambitious objective is to make 24 piston-fit drawers. Let’s also assume the wood he uses for each drawer-front is unique in both appearance and warpage. It’s a heck of a lot of wood to cut and with no time to waste, so our erstwhile wood butcher gets out his trusty handplane, sharpens it up, adjusts the blade and chipbreaker, gives it a kiss for luck, and without further delay makes the shavings fly through the air in glorious fashion!

But wait a minute! No matter how much Woody planes, he just can’t seem to make some of the surfaces flat, free of wind and the sides square to the faces. It’s like some kinda frikin moving target! Indeed, eventually he is dismayed to discover some of the edges are getting too thin. What to do, what to do!?

Drama queens typically begin interesting antics at this point, but not so our Beloved Customers who, unlike Woody, are stoic, laconic, intelligent and of course, sharply-dressed, and therefore pause their physical efforts to focus their mental powers on solving this mystery. At this point BC’s benchdog perks up his ears and tucks in his tail in fear of the humming emanating from his master’s ears, his benchcat arches his backs, hisses like a goose, and flees the workshop like his tail is on fire, and the resident pixies frantically hide in the lumberpile to avoid being disrupted by the power they sense radiating outward from BC’s mighty brain.

Of course, the conclusion you eventually arrive at is operator error. After then there is cat urine to deal with…..

Too few people really pay attention when using their tools, focusing too much on the joy of making as many chips or shavings as quickly as possible without a plan. For example, a failure common to many woodworkers is to start planing without first identifying and marking the high spots that must be cut down first, and then areas to be cut down next. In other words, they fail to plan the sequence of the work. The result is that time, steel and sweat is wasted cutting wood that didn’t need to be cut while ignoring wood that did need to be cut. And all for lack of a plan measured with a straightedge or dryline and written on the board with a few strokes or circles of a lumber crayon or carpenter pencil

This mystery too has been known to increase profits of the mental health industry and even (heaven forfend!) fashion decisions involving poorly-tailored canvas jackets with crotch straps. Simply not to be borne!

The Mystery of the Sounding Board

Lastly, we come to perhaps the most frustrating and least-understood of the Mysteries of Woodworking. Not to say there are no other mysteries, because there is always that most ancient of riddles that baffled even the enigmatic Sphinx, one which has been repeated endlessly since before Pharaoh wore papyrus nappies, of why Woody would respond honestly to his wife when she asks him if her new pair of jeans makes her bottom look “simply humongous.” Sadly, this is one mystery upon which your humble servant is unable to shed light because even I do not fully understand the heart of woman.

But I digress. This Mystery is one that torments those badly befuddled souls like friend Woody who, lacking a plan to follow, eyes that see, hands that feel and ears that hear, unwisely assume that the board they are working on is stable simply because it doesn’t walk away from him. Perhaps it is the malevolent influence of pernicious pixies that causes himm to ignore the downward deflection the pressure of their plane unavoidably induces in a warped, unevenly supported board, or in a board being planed on a flimsy or crooked workbench.

This unintentional, indeed unnoticed deflection too often causes the board to escape the cutting blade resulting in hills being raised and valleys remaining low where flat surfaces were required. Of course, this leaves the handplane bitterly dissatisfied because it wanted to do good work too.

But this waste of wood, steel, sweat and goodwill can be avoided because, even if the board isn’t rocking like Zepplin and dear Woody can’t feel the board deflecting away from his plane’s cutting edge, he could detect the change in his plane’s song when it is cutting an unsupported area of a board if he only listened because the board is also a “sounding board.”

Think of all the money saved that Woody would otherwise spend on lithium, Prozac, and small hotel rooms with padded walls to ease his mental anguish if only he had the foresight to make a plan, train his hands and eyes to confirm his tool’s performance, and his ears to listen to what his plane tries to tell him.

The experienced professional will investigate each board, make a plan for his work, mark the plan on the wood, shim the board so it is evenly supported on a flat workbench surface, and sharpen his blade if necessary before making a single cut. Then instead of cutting randomly like a modern artist wielding a paintbrush, he will make each cut intentionally, purposefully, in accordance with his plan to make each cut as efficient as possible.

He will also pay attention to the reaction of the wood and feedback from his tools during each cut. He will use the four habits discussed above, and maybe even a drop or two of unicorn wee wee to limit tearout if his budget allows.

If Beloved Customer doesn’t have a master to give you a dirty look or to box your ears when you impatiently err, you must train yourself. Slow down. Make a plan. Execute the plan. Pay attention, use your senses, and spend the time needed to evaluate progress against the plan. Consider carefully why the work is going well or why it is not. This process will slow the work down at first, but over time it will help you develop good habits and guide you along the path to becoming a master craftsman instead of just the typical woodcutter.

May the gods of handsaws smile upon you always.

YMHOS

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

Please share your insights and comments with everyone 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 my straightjacket dig into my crotch.



Testimonial

N.G., Bozeman, Montana, USA

We occasionally publish testimonials from our Beloved Customers. This one by a talented and diligent professional in Montana is especially well-written, and representative of much of the customer feedback we’ve received over the years. More importantly, it contains pictures of a beautifully-made solid-walnut table.

Stan Covington, C&S Tools

As a 4th generation carpenter, I’ve always been interested in the legacy of well crafted items. Finally, after 25 years as a carpenter I was ready to build my collection of heirloom-quality hand tools.

I’ve owned many chisels, most of them new Stanley chisels, but they never held a satisfactory edge. I bought some older chisels off eBay and rehabilitated them, hoping for a better steel (based on my research), but the blades always curled when they hit knots.  During my in-depth research of quality chisels I eventually came across Covington and Sons Tools.

I learned a lot from the C&S website and blog posts. Stan took the time to make sure I was purchasing the right tools for my needs.

The tools that Stan provides are made by craftsmen whose attention to detail and legacy is crystallized in the tools they forge. You’ll know what I mean when you use them.

Honing a high-quality blade to a mirror finish, and then feeling it slide through wood with just light hand pressure is an experience lesser woodworking tools truly cannot provide.

Working with people who understand quality is a pleasure.

Here are some photos of my most recent project, using chisels and a plane purchased from Covington and Sons.

N.G.

Japanese Handplanes – Part 1: East Vs. West

The Road goes ever on and on,
Down from the door where it began.
Now far ahead the Road has gone,
And I must follow, if I can,
Pursuing it with eager feet,
Until it joins some larger way
Where many paths and errands meet.
And whither then? I cannot say.

The Road goes ever on and on
Out from the door where it began.
Now far ahead the Road has gone,
Let others follow it who can!
Let them a journey new begin,
But I at last with weary feet
Will turn towards the lighted inn,
My evening-rest and sleep to meet.

Bilbo Baggins
C&S Tools Sukezane brand 70mm finish plane. Shirogami No.1 steel blade hand-forged by Nakano Takeo, body by Inomoto.

Your humble servant has received many inquiries over the years from Honorable Friends and Beloved Customers (may the hair on their toes never fall out!) about how to setup, maintain and use Japanese planes to which I have gladly responded when the request for information was made politely.

The Japanese hiraganna handplane is an elegant tool with a simple yet deceptively sophisticated design. It is not a difficult tool to master once one understands its unique design principles and learns a few basic techniques easily taught in person, but it can be frustrating to master using only written guidance.

But I believe the time has come to begin this journey. I pray Beloved Customers will have the courage to accompany me down this road that goes ever on and on until we reach the lighted inn. When we arrive, the first round of root beer will be on me!

Let’s begin the journey by examining some relevant terminology. Don’t forget your handkerchief!

Terminology

The Japanese Yariganna in-use. Prior to the advent of the handplane to the islands of Japan, an approximation of this tool was used for finish-planing the surfaces of wood following the adze. It creates a unique and practical surface texture.

In this and subsequent posts in this series your humble servant will not attempt to educate Gentle Readers in all the Japanese language terms for every part of the plane, nor will I use Japanese conventions for describing handplanes, since that would be about as useful as ice skates on Bambi. Instead I will use standard English language terms wherever possible. There is an illustration below that shows the various components and features along with Japanese language labels for those interested.

Indeed, since the plane is a relatively recent tool in the Japanese woodworker’s toolbox, and has a much longer archeological history in the West, it seems silly to use more Japanese words than absolutely necessary to describe something that did not originate in Japan, and can easily be described in English. I will, however, venture to describe some of the more common general terms specific to the Japanese handplane.

I am neither a lawyer nor a government employee and so see no need to make things more confusing than necessary. I humbly apologize in advance if this approach offends any purists who enjoy being confused.

The standard handplane in Japan, and the one used for creating and/or smoothing flat surfaces (versus rabbet, chamfer or molding planes) is called the “hiraganna,” pronounced hee/rah/gahn/nah, and written using the Chinese ideograms 平鉋 , without emphasis on any part of the word.

The first character 平 is pronounced, in this case, “hira” (there are at least 6 standard pronunciations for this character in Japanese) and means “flat.” makes sense, right?

The second character 鉋 , written “kanna” in the Latin alphabet and pronounced “kan/nah,” means “plane” (as in “handplane”). This character is comprised of two standalone characters combined to make a single character, a common practice in the Chinese and Japanese languages. The one on the left side, 金, means gold or metal, while the one on the right, 包 means “to wrap.” Kinda sorta makes sense. Almost hardly.

The character for kanna was not invented in Japan but is said to have been used in China since the Táng period AD618 – 907, although the tool it represented at the time was a scraper of sorts and not a handplane.

Comparison Between Western and Japanese Wooden-bodied Bench Planes

If your humble servant may be permitted a brief digression on a personal subject, I would like to clarify a point of some small relevance to this explanation of the Japanese handplane.

I have at times been called a Japanophile, and although I confess to being fond of the mountainous islands and the wonderful people of Japan, the years I have spent living in Japan, and my ability to read, write and speak the language were not born of some starry-eyed infatuation or even simple admiration of Japan, but by more practical matters of service obligations, educational pursuits and my work in the construction industry. My point is that I prefer Japanese tools and techniques when I think they are superior, and by the same token prefer Western (or at least American) tools and techniques when I believe they are superior. Consequently, I like to flatter myself that I can provide a relatively unbiased viewpoint, one which will come into clearer focus near the end of this article.

Of course, those who prefer Western tools and techniques will say I am biased towards the Japanese way, while those who prefer Japanese tools and techniques above all others will insist I am biased toward Western tools and techniques. There is no way to win such an argument, so Gentle Readers must judge for themselves. Anyway, back to the subject at hand.

A detailed treatise comparing wooden-bodied Japanese handplanes to steel-bodied Western handplanes would be an extravagant waste of Beloved Customer’s precious time, so I will resist the temptation.

But I would be remiss to not point out that Bailey-pattern steel-body handplanes do have a few serious advantages over wooden-bodied planes in general, while wooden-bodied planes in general and Japanese hiraganna planes in particular have several serious advantages over modern Bailey-pattern planes the thoughtful woodworker should understand.

Some of the advantages of modern steel-bodied Baily-pattern planes over all wooden-bodied planes include the following:

  1. The steel plane’s body is unaffected by seasonal humidity changes and therefore warps less and requires less fettling. This is a huge advantage;
  2. The steel plane’s sole is harder and wears slower than a wooden sole, and therefore requires less fettling. Also, since wear is less, the mouth does not easily become wider, and seldom if ever needs to have a new mouth inlet. This is another huge advantage.

Both of these advantages can have a huge impact on the effectiveness and productivity of the tool over the years.

Some of the advantages of Japanese wooden-bodied planes over steel-bodied planes include the following:

  1. The wooden body is lighter and not as easily damaged as a traditional cast-iron steel-bodied plane’s body which will bend and/or fracture if dropped onto a hard surface (the ductile cast iron used in some high-end planes nowadays is a significant improvement in this regard). Fracturing has been the bane of steel-bodied planes since the beginning. This is a huge advantage;
  2. The plane’s Owner can make a replacement wooden body, exactly as he prefers it to be, quickly and inexpensively;
  3. The wooden sole is softer than a steel sole and therefore is not only less likely to scratch the surface being planed, but tends to burnish it instead;
  4. The wooden sole is easier to true, fettle, and even modify;
  5. The wooden body is lighter in weight and therefore both less tiring to use and easier to transport;
  6. Japanese handplanes have lower profiles so they take up less volume, and are easier to store and transport;
  7. Japanese handplanes have few if any screws or levers so adjustment is simpler, more intuitive, and entirely dispenses with the clumsy, often sloppy mechanical linkage common to Bailey-pattern steel-bodied planes;
  8. And finally, the biggest advantage of the Japanese handplane is, (drumroll please), the blade, if hand-forged from high-quality steel and properly heat-treated, will become much sharper, stay sharper longer and will be easier to sharpen than the blades of modern steel-bodied Bailey-pattern handplanes. No contest. Your humble servant believes the blade’s performance is the most important aspect of a handplane, after all, it is a cutting tool, not a paperweight (although I admit to having a pretty little LN No.1 benchplane in white bronze I use as a paperweight. My associates here in Japan can’t figure out what it is. I tell them it is for shaving kiwi fruit (ツ)).

Allow me to expound a little further on the advantages of the Japanese handplane:

Blade Performance:

A beautifully-polished kanna blade with what appears to be excellent grey jigane and a milky-silver hagane cutting edge. It takes your humble servant’s breathe away.

The Japanese planes we carry have forge-laminated handforged blades made for specialized high-carbon tool steel to meet the performance expectations of professional woodworkers in Japan. The crystalline structure of this steel once made into a blade by our blacksmiths is fine-grained and uniform. Blades are exceptionally hard at 65~66Rc, and remain sharp a long time while being easily sharpened.

There was a time in centuries past when Western blades were of near equal quality, but no longer. Sadly, the blades of most Bailey-pattern planes manufactured nowadays are made of high-alloy steels for which quality control can be easily automated, but which were never intended for handplanes. These steels are undeniably tough, won’t become very sharp initially, quickly dull, and are an “evil screaming bitch” to sharpen (pardon the excessively-technical jargon).

Blade Appearance:

While it used to be that Western wooden-bodied planes had interesting maker’s marks stamped in their blades, such is no longer the case. Japanese planes, on the other hand, make a point of having decorative engraving, stampings and surface treatments applied to their blades for a significantly more interesting presentation of the blacksmith’s art than the plain, boring sanded steel of modern Western planes.

A plane by Usui Kengo with a nekkiri yabane (cut arrow feather) ground and stunningly artful calligraphy handcut into the face.

Reliable Blade Retention:

The blade of Japanese handplanes is wedged tightly into two grooves in the side of the body preventing shifting and rotation, and providing reliable settings. Most modern Western handplanes rely on a relatively complicated and less-secure blade retention and adjustment mechanism.

Simplicity:

The standard Japanese hiraganna plane has at most 4 components: The body, blade, chipbreaker (uragane), and chipbreaker rod. Planes with adjustable mouths will have more parts, but those are not standard planes. Western planes often, but not always, have at least 21 and sometimes more components. Screwdrivers and wrenches are not necessary for adjusting or disassembly of Japanese handplanes.

And all the parts in Bailey-pattern handplanes have built-in slop which grows worse with use and often makes adjustment irritating and sometimes even unreliable.

The Japanese hiraganna does not have a separate wedge or a mechanical assembly securing the blade in-place. Instead, the blade itself is wedge-shaped, narrowing in thickness from the head to the cutting edge, and fits tightly into two grooves, one cut into each sidewall of the mouth opening, for a secure fit, an elegant, simple and utterly reliable design.

The various component parts of a Japanese Hiraganna. There are only 4.

Lower Profile and Reduced Weight:

Japanese hiraganna have thinner bodies and a lower profile than Western Bailey-pattern planes and even Western wooden-bodied planes. Accordingly, they weigh less and take up less space in the toolbox.

While there are times when your humble servant appreciates the extra momentum a heavier steel body affords when making deep cuts, those instances are limited to specific applications. The rest of the time the extra mass is like most government agencies: a pointless burden.

In all other applications, the lighter weight of the wooden-bodied Japanese hiraganna plane is a blessing.

Smoother Surface

Where wooden-bodied plans of all types excel is the superior finish they leave on the wood they are used to plane. That is not to say steel-bodied planes cannot create a perfectly smooth surface, but it is the nature of steel to develop dings and burrs in-use that can leave scratches in the wood they are planing. And while a wooden sole will burnish a wooden surface, the best steel can do is rub it.

Western Steel-bodied Handplanes: The Right Tool for the Right Job 適材適所

There is a saying in Japan I am told comes from the boat-building tradition where many types of wood are used for the various components in a quality vessel that goes like this: Tekizai tekisho 適材適所 meaning: “The right wood for the right place.”

Your humble servant is a pragmatic son of a gun, and a firm believer in using the best tool available to achieve the best results. Accordingly, it would be exceedingly foolish to insist that Japanese handplanes are always the best tool for every planing job. Indeed, I have used a combination of both Bailey-pattern steel-bodied handplanes and Japanese-style handplanes for many decades, selecting the best tool for the specific job at-hand. So what steel-bodied planes do I believe excel?

Scrub Plane

I have found the Stanley No.40 furring plane and especially its more modern equivalent the Lie-Nielson 40 1/2 scrub plane to be superior for removing material when dimensioning lumber (making it thinner and flatter).

This is an extremely simple plane with a narrow, thick blade 1.450″ x 3/16″ ground to a large curvature and a big mouth designed to hog lots of wood. The handles make it easier to leverage body weight into the cuts.

In the case of the LN Bedrock model, the blade is A2 steel, a material developed originally for dies, not plane blades, a tool steel that will never become especially sharp, and which dulls quickly, but once it has dulled to a certain point simply keeps on cutting seemingly forever. And while the blade may become dented and dinged, it will not easily chip, perfect for the rough work of dimensioning dirty and stone-infested rough-sawn lumber.

The ductile iron sole will be of course be scratched by dirt and stones hidden in the wood, but who cares? Better a steel scrub plane than the white oak of my Japanese planes. I consider Lie-Nielson 40 1/2 to be an essential plane in my toolchest.

Block Plane

The steel-bodied Western block plane is also an essential tool IMHO. There are of course Japanese planes with similar dimensions, of lighter weight and with better blades, but they all have one weak point, namely the area right in front of the mouth becomes scratched and wears too quickly. Block planes are often used to trim and clean edges which apply a high point load on the mouth. The fix used in Japan is to inlet a brass plate at the mouth. But if metal is the answer, why not make it metal from the beginning?

Also, I use my block planes for finish carpentry and installations which involves working around hidden finish nails, little pieces of steel that damage wooden bodies and hard blades, but which a steel block plane shrugs off.

I own several block planes, being fond of experimenting with tools, but have found the Lie-Nielson No. 60-1/2 rabbet block plane with nicker to be the one most useful for me.

Jointer Plane

Another Bailey-pattern steel-bodied plane I consider to be excellent is the jointer plane. I once had an old Stanley No.7 jointer plane I bought at a flea market, but it fell from the back of my 1966 VW van many moons ago and suffered the fate common to old grey cast-iron planes, breaking both the body and my heart in half. I bought the Lie-Nielson version many years later and have been pleased with it’s perfomance (my expectations were never very high).

It is a monster at 22″ long and weighing 8-1/4 lbs. I hate the heck out of the A2 steel blade. To make things worse, the sole was warped when I bought it new, so I had to spend hours flattening it on sandpaper and glass. Why do I like it? The cast ductile iron sole is tough and never warps. The extra length makes it especially stable for cuts ending or starting off the piece of wood I am planing. When I have a large surface such as a table to flatten, my No.7 may not cut like a dream or be easy to use, but it always makes the job go quicker.

Conclusion

In this post we have briefly touched on the history, terminology, advantages and disadvantages of the Japanese hiraganna plane. We have also compared it to Western planes, and concluded with several examples of Western handplanes your humble servant believes to be superior to their Japanese counterpart.

I hope you will agree that the Japanese handplane is a tool worth mastering if only because of the excellent work it can help you execute. Besides, they’re a lot of fun.

In the next post in this story of supernatural intrigue and inter-dimensional romance we will discuss how to properly adjust a Japanese hiraganna plane without hurting its feelings.

YMHOS

Look at them,’ mother Troll said. ‘Look at my sons! You won’t find more beautiful trolls on this side of the moon’ John Albert Bauer (1882–1918)

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Other Posts in the Japanese Handplane Series:

The Mystery of the Brittle Blade

There are few blessings without a curse hidden inside, nor curses without a whiff of blessing. Like most things, it’s a matter of how you look at it.

Joe Abercrombie, Isern, “A Little Hatred”

In this article your humble servant will seek to unravel for Gentle Reader another aspect of the ancient “Mystery of Steel.”

This story does not begin on a dark Scottish moor, nor on a foggy London night in a drawing room with the door inexplicably locked from the inside concealing bloody mayhem splattered across intricately carved linenfold oak paneling; Rather, it begins in an ordinary woodworking shop. And it goes something like this.

The Brittle Edge

The curtain rises on a humble detached workshop where, unbeknownst to our victim, an erstwhile woodworker we shall call “Woody,” dastardly events are about to unfold (cue the deep, ominous music). It’s really just an old dilapidated garage, but it’s Woody’s kingdom and he is master here, or so he imagines. He’s expecting us, so we’ll just go on in.

Make sure the door is firmly closed behind you now; It tends to stick and Woody’s bench dog loves to jet out and root around in the neighbor’s garbage. No need to solve the mystery of why they call the fuzzy little leg-humper “Stinky.” (ツ)

Pine and cedar plane shavings litter the floor of Woody’s shop and their fragrant aroma fills the air erasing the mutt funk. Autumn sunlight filters gently through the single dusty window as sawdust motes dance above a limp bench cat sleeping at the far end of the workbench dreaming of buffalo wings and big-eyed kittens. All appears well in Woody World.

Woody’s sitting at his workbench on his white Smith & Wesson padded stool where he has just unpacked his new chisel, admired it, checked the fit, finish and edge, and appears quite satisfied. He lays out a test mortise hole on a piece of scrap oak, picks up his gennou hammer (the one with the classic Kosaburo head and the sexy Osage Orange handle that turned out so well), and begins to chop a test mortise. But, wait!… Something’s not right!

With trembling hands, Woody examines the chisel’s cutting edge to discover the last thousandth of an inch or so has changed from smooth and sharp to ragged and dull. “Nooooo!” Woody wails as he lifts his arms to the ceiling, arches his back, and slumps to the floor on his knees in a pose reminiscent of Sergent Elias in that poignant moment on the battlefield; “I have been betrayed!” he screams with wavering voice. Yes, Woody’s a talented and enthusiastic drama queen in the Smeagle mold; Maybe even good enough to run for the US Congress.

Another of Woody’s qualifications for high public office is that he dearly loves to pull a cork, so while he walks to the corner Piggly Wiggly to get a 5th of tequila to anesthetize his emotional shock and refill his thespian fuel tanks, let’s take a load off and sit on his workshop sofa over there while I explain the cause of his emotional fragility. Yep, you’re right; It’s a recycled bench seat from an old Power Wagon he salvaged from a junkyard and converted to a sofa for watching ballgames and taking naps in the shop away from the jaundiced eye of “She Who Must Be Obeyed.” Don’t worry about your pretty pink dress, princess, it’s just honest sawdust.

With tools, tequila, and the mystery of steel involved, this could be a long story, so let’s consider how to solve this particular mystery before Woody gets back and starts up his caterwauling again.

But just so you don’t become discouraged, let me state right now that there is a tunnel at the end of the light, and that while all seems dark and hopeless to Woody now, he may actually have reason to rejoice greatly! But we’ll get back to that later in the story.

The Questions

A Japanese blacksmith fluxing and placing a piece of high-carbon steel onto a hot piece of jigane in preparation for forge-welding the lamination of a blade.

Your humble servant always asks the following questions when someone complains of a chipped cutting edge on a chisel or plane. When Woody gets back, and if he manages to remain coherent and vertical long enough, we’ll ask him these same questions. If your blades are causing you grief, you should consider asking yourself these questions too. Jose Cuervo and acting skills are not required.

  1. What sort of quality is your problem chisel? Low? Medium? High? How do you know? This is relevant because a poor-quality chisel will fail just by looking at it too hard;
  2. What type of chisel is it? A striking chisel or a paring chisel? Each type of chisel is used for different tasks and in different ways;
  3. What and how were you cutting when the edge failed? This is important because some woods are best cut in a different manner than others, and some cuts require a special approach if we are to avoid damaging the chisel;
  4. What is the bevel angle? If the angle is much less than the ideal for the type of chisel, plane, cut and wood, we may have found the culprit. Finding the perfect angle for your chisel and situation may take some experimentation;
  5. How did the edge fail? Did it crumble? Chip? Roll? A combo failure (with cheese)? This will tell us a lot about the tool.
  6. Was the wood you were cutting dirty? Did it contain embedded grit? This is an important question because many people carelessly use their valuable chisels, planes and powertools to cut hard minerals instead of scrumptious wood. The lesson? Don’t be a slob: Scrub your wood with a steel brush before cutting it. And saw off the last 3~4 millimeters of every board, or at least chamfer the ends with a block plane, drawknife or knife to remove the grit always embedded in end grain, before you put it through your jointer, thickness planner or tablesaw, or cut it with handsaws, planes or chisel. If you have not made a habit of doing this, don your scratchy sackcloth tidy whities, smear ashes on your face, then repent and be baptized because you have been abusing your innocent tools, Bubba. Clean your wood and you will notice the difference. Strange that no one I have ever asked this question to has admitted to using dirty, stony wood at first. The reason is usually simply that they didn’t realize it was filthy until I pointed it out to them, just as it was pointed out to me many years ago. What’s that you say? You don’t have a stiff steel wire brush in your toolbox?! Shame on you;
  7. Did you abuse the chisel by trying to lever wood out of the cut, a mortise for instance? This is a common cause of failure. People accustomed to using amateur-grade tools with soft cutting edges frequently discover the edge of their new chisel chipped after using it like a cheap Chinese screwdriver to lever waste, never imagining the harder and more brittle steel of a quality chisel might be damaged. Such boorish behavior voids the warranty on our chisels, BTW, because a chisel is a cutting tool, not a prybar or a can opener, much less a screwdriver.

Did your answers to these questions suggest any remedial action to you? The best answer to Question 1 is often to procure a better-performing tool.

But if your tool is professional-grade instead of hardware-store grade, then you need to learn how to use it and maintain it properly. But that is a story for another day.

Let us shift our attention briefly to another, related mystery, one that has more to do with human nature.

Why Are the Blades of So Many Modern Tools Mediocre Performers?

It wasn’t always that way, but there are sound business reasons why chisel and plane blades are such poor performers nowadays, even in Japan, and like many things, it boils down to money. The numbers of craftsmen that routinely use handtools has decreased, and therefore the demand for professional-grade tools is way down. In Western countries the degradation of tool standards started even earlier.

In this situation, mediocre tools are simply more profitable. After all, low-quality materials are cheaper and it only takes ordinary machines and minimum-wage factory workers, not expensive trained blacksmiths, to make tool-shaped objects from mediocre-quality materials. Professional woodworkers won’t touch such crap, but amateurs, the inexperienced and those deluded, wandering souls who judge performance based solely on lowest cost buy them by the ton. More now than ever, sustainability is given pious-sounding pompous lip-service, while the reality of modern society is that high-volume sales of colorful but poor-quality tools designed to meet planned obsolescence goals, manufactured in lots of thousands by Chinese farmers, and destined to become early landfill stuffing has become the only viable business model left standing. Gofigga.

More importantly, even if they would do better if given half a chance, inexperienced amateurs seldom have anyone to teach them how to use and maintain their tools, so they never learn proper maintenance principles and cutting techniques. When they damage their woodworking tool blades carelessly, they blame the tool supplier for their own failure. As Mr. T would say: “I pity the fool.”

Faced with this sort of consumer, it is simply easier and more profitable for tool companies to manufacture, and for retailers to sell, chisels and planes with softer, tougher blades suited to amateurs. I think you can see the vicious cycle.

A kakuuchi oiirenomi chisel by Hidari no Ichihiro
An Atsunomi chisel by Hidari no Ichihiro

A Non-technical Technical Explanation

Your humble servant’s earlier comment that Woody may have cause to rejoice about what appears to be metallurgical malfeasance may cause some Gentle Readers to wonder if I am mad as a sack of owls; Perhaps my most excellent aluminum-foil skull cap (the one with purty curly copper wires) malfunctioned permitting those icky inter-dimensional aliens’ mind-control waves to leak through.

Like our absent drama queen, I too was devastated when first faced with the Mystery of the Brittle Blade, but I can explain why it may be sign of a blessing instead of a curse. It’s elementary dear Watson. But I think it best to provide some background and explain some time proven solutions before presenting the good news. Steak before ice-cream, you see.

I beg the indulgence of knowledgeable Gentle Readers who feel insulted by the lack of temperature curve drawings and jargon such as “pearlite,” “martensite” and “ austentite,” and ask them to understand that, while this blog is focused primarily on informing our professional Beloved Customers, many Gentle Readers require a less technical explanation. Simple hospitality demands that your humble servant make an effort to provide useful insight to a wide range of Gentle Readers. As a dude wearing a skirt and sandals in a movie once said: “ Are you not entertained?”

A shinogi oiirenomi chisel blade by Hidari no Ichihiro

Quenching the Blade

When a blacksmith quenches a high-carbon steel blade in water in the ancient manner (called “Yakiire” 焼き入れ in Japanese which translates to “burn in” in English), the steel suffers a thermal shock, sometimes severe enough to crack it. This violent cooling also causes a peculiar crystalline structure to form in the metal, one that causes it to become harder and increase in volume, and to warp to some degree. The casual observer may imagine the water cools the entire blade uniformly, but ‘tain’t so.

Those areas of the blade that cool the quickest form the highest volume of crystals and become hardest. In the case of chisels, planes, and kiridashi knives, the end of the blade has the most exposure to water, cools quickest, and therefore becomes hardest, at least during the first quench.

The blacksmith may carefully repeat the heating and quenching process multiple times, sometimes varying the heat time and temperature to achieve the desired crystalline structure and uniform distribution of small, hard carbides that define “fine-grained steel,” but the quenching process by itself always leaves the blade too hard and too brittle to be useful as-is.

Tempering the Blade

Now that the blade is hardened, indeed too hard, the blacksmith must mellow the steel, reducing its hardness while at the same time increasing its toughness by carefully reheating and cooling the steel to modify the crystallized steel in a process called “tempering,” in English and “yakimodoshi “ 焼戻し ( literally “ burn return” ) in Japanese. In this way, a steel blade hardened to Rc85 degrees during the first quench, indeed brittle enough to break into pieces if dropped onto a concrete floor, can be softened to a useful hardness while becoming at the same time much tougher.

In materials science and metallurgy, toughness is defined as the ability of a material to absorb energy and elasticly deform without fracturing. To “elasticly deform” means an object changes shape or deforms when pressure is applied, but returns to its original shape when the pressure is removed. For instance, if you clamp one end of a piece of mild-steel wire in a vise and apply a little force with your hand at the other end it will bend at first and then spring back to its original shape when you remove pressure. This is called “elastic deformation.” But if you apply enough pressure the wire will not spring back (“rebound”) but will remain bent. This permanent bend is called “plastic deformation.” Mild steel wire is truly “tough as nails.”

Glass is the opposite case. While it may exhibit more elastic deformation than most people realize it can, it will tolerate no plastic deformation, because when the stresses in glass reach the “yield point,” instead of bending plasticly, it breaks.

A brittle blade is hard but not tough, and while it will elastically deform a little bit (often so little it’s unnoticeable), it too easily breaks. Proper tempering therefore, is critical.

But this reduction in hardness and increase in toughness brought about through tempering is not always 100% uniform, and as mentioned above, the extreme cutting edge of the blade of a chisel or plane tends to be hardest and therefore most brittle in the case of hand-forged tools, even after tempering. The cheap, mass-production solution is to simply make the entire blade softer, say Rc55 for example, so brittleness will never be a problem. But such a tool is more a sharpened screwdriver than a cutting tool suited to the needs of professional woodworkers, IMHO.

I’m being too harsh, you say? Not even a little bit. A soft blade dulls quickly, wastes the professional woodworker’s time and money, and is irritating instead of useful. Perfect for turning screws, spreading spackle or stirring paint but not much good for quickly and precisely cutting lots of wood for pay, thank you very much.

Solutions 1 & 2

The Mystery we are investigating on Woody’s behalf is as ancient as steel itself. And of course there are reliable ancient solutions our blacksmiths employ. Let’s consider two of them.

First, create a crystalline structure in the blade through hand-forging that is more resistant to fracturing than ordinary steel regardless of its hardness. This doesn’t happen by accident.

Second, employ painstaking heat-treatment techniques combined with uncompromising quality control to achieve the right balance of hardness vs. toughness.

To help control the heat-treat process, our blacksmiths apply a special mud-like compound to specific areas of the blade to slow down the thermal shock during the quench and improve the steel’s crystalline structure. Every blacksmith has their own “secret sauce,” so I can’t tell you what it’s made from. This technique is not perfect nor unique to Japan, but we know it has been successfully used by Japanese swordsmiths for at least 900+ years

It ain’t rocket surgery, but factory workers in Guangzhou or Mumbai can’t do it.

So, we have discussed the reasons, and some solutions, but what to do about a blade that’s already chippy?

Solution 3

Assuming the blade has been forged by an expert blacksmith in accordance with the principles outlined above, the fix to chippiness (oops, did I coin a word?) is to be patient and sharpen the blade three or four times removing the extra-brittle steel exposed at the cutting edge, the area that became harder and less tough than the rest of the blade during the heat-treating process. With few exceptions, the blade will then “calm down” and stop misbehaving.

This is the solution we ask our Beloved Customers to employ when this problem infrequently arises. It requires faith, and patience, but it almost always works.

Solution 4

The last solution, and one I certainly do not recommend to anyone except as a last resort, is to heat the cutting edge under a candle flame. Not an acetylene torch; Not a propane torch; Not even a butane lighter; A candle flame only. You want the extreme cutting edge to become just a smidge hotter than you can comfortably touch with your bare finger. Don’t heat the entire blade, just the cutting edge.

BIG FRIKIN DISCLAIMER 1: This method won’t fix a poor-quality blade or one that was initially ruined during forging or heat-treat.

BIG FRIKIN DISCLAIMER 2: If you are careless and do this wrong you can easily ruin the blade!

Rejoice Greatly!

But what insanity made me say that Woody should rejoice when the cutting edge of his new chisel crumbles? I assure you, my reasoning is sound, I have Woody’s best interests at heart, and I will explain all to him when he sobers up. Probably tomorrow afternoon, at this rate. (ツ)

But I’ll explain it to you now, if you will be good enough to get me a root beer from Woody’s cooler over there to wet my whistle. No, that’s not a Class M-3 Model B-9 General Utility Non-Theorizing Environmental Control Robot, it’s one of those mini-fridges sitting on two skateboards with a shop-vac wrapped in Christmas lights perched on top that Woody puts out on his front porch for Halloween to thrill the kids and to keep a sufficient stash of cold adult beverages, and root beer too, of course, close at hand. He’s very practical that way. Oh, BTW, please don’t tell SWMBO about the adult beverages, or you’ll ruin a great Halloween tradition and preclude many erudite discussions in the future: Vino Veritas

Ahh, that’s better. Nothing like an ice-cold root beer.

Now where was I? Oh yes, the reason for my optimism: A high-quality blade that crumbles like Woody’s did when brand new, and mellows after a few sharpenings, is highly likely to be an exceptionally fine tool!

On the other hand, a blade that is too soft when new will never crumble or chip, but it will always quickly dull and never improve. A veritable gasket scraper. (个_个)

There are exceptions, of course: some hand-forged blades are defective and crumbly from beginning to end, usually a result of overheating the steel during the forging process, a rookie mistake. You should return such a defective blade to the retailer you purchased it from. If, however, to save a few bucks, you bought a tool without a warranty, or purchased it from an online auction, you will need to enlist the services of Murphy’s two bubbly buddies Mr. Doodly and Mr. Squat.

Somehow I doubt Woody will thank me for solving this piece of the Mystery of Steel for him, but I am confident he will love the flavor of that chisel for the rest of his life.

YMHOS

PS: If you found this interesting, you may find other posts regarding the Mystery of Steel found in our “Sharpening Series” interesting too. The one at this link in particular is relevant to this discussion.

A kakuuchi oiirenomi chisel by Hidari no Ichihiro

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 I gag on a hairball if I lie.

Relevant Posts:

The Story of a Few Steels

Professional-grade Tools

The Japanese Sumitsubo Inkpot 墨壺

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 version, 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 travels through holes at each end of a “pond” filled with absorbent silk or cotton waste soaked with ink, and then spools around a wheel or reel. As the line is let out it soaks up ink from the pond.

In Japan, a wooden bob 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.