“The beginning of wisdom is to call things by their proper name.”
The “Tsuba” in Tsuba Nomi is the Chinese character 鍔 which means “guard” as in a sword or knife guard.
Two nubs attached to opposing sides of the blade just below the handle look like the guard for a knife or sword. This chisel is driven with a hammer to quickly create a pilot hole for nails or screws. The blade becomes tightly wedged into the wood, but by striking up on these projections with a steel hammer, the blade can be extracted.
This unique chisel comes with blades with round, square, or rectangular cross-sections.
Square and rectagular blades usually have a chisel-point beveled on two sides, but sometimes are beveled on just one side. Round blades may have simple pointed ends, but sometimes they have short triple tines to drive the crushed wood fibers into the hole.
While this chisel severs the wood fibres, unlike an auger, drill, or gimlet, it does not remove material from the hole. The ends of the severed fibers are angled down into the hole, and over time and exposure to humidity and water, will partially swell back to their original shape locking nails in tightly.
This chisel is still used in the wooden shipbuilding industry, but other than that sees very little practical use nowadays. I own one but have have never used it in anger.
“There is a great satisfaction in building good tools for other people to use.”
This is the second and final post about the heavy-duty Japanese carving gouges.
The Sotomaru Nomi” 外丸鑿 is what is called an “Incannel Gouge” in the West. “Soto” 外 means “outside” or “external,” “maru” 丸 means “round,” and “nomi” 鑿 means “chisel.” The name corresponds closely to the English language term for incannel gouges.
As with other Japanese chisels, the Solomaru nomi has a thin layer of high-carbon steel laminated to a softer low-carbon steel body with a neck and tang. They also have the ferrule which compresses the handle’s wood to keep the blade’s tang firmly attached to the handle and prevent the handle from splitting, and a crown to prevent the handle from cracking when struck with a steel hammer. Unlike most Japanese chisels, however, they do not have a hollow-ground ura.
The cutting edges differ from their Western counterparts in that the bevel is a single, flat plane, instead of a curved surface. The advantage of this detail when sharpening would be difficult to overstate. The blade can be sharpened on a normal, flat sharpening stone without pesky slips, finger contortions, or heaven forfend, miniature die grinders.
This is an unusual chisel outside Japan, but is indispensable for working round wood and bamboo used in Japan’s sukiya and teahouse construction traditions. Although this chisel has many advantages, it will not waste wood as rapidly as the uchimaru chisel we looked at in the previous post. Its shape is more conducive to cutting precisely curved surfaces than its concave sisters.
The hard steel lamination in this chisel has more support than its brother the uchimaru gouge we looked at in the previous post, making it a bit tougher.
Sharpening is easier and quicker than other gouges because the bevel can be treated as a single flat plane. The area called the “flat” or “ura” on conventional chisels is convex so it can be worked on a flat stone eliminating entirely the need for those pesky grooved stones and slips.
The disadvantage is that the flat bevel/curved cutting edge cannot make clean stopped cuts against 90 degree surfaces. This shortcoming is easily dealt with, however, by making a few more passes.
The sotomaru nomi is perfect for fitting straight line curved surfaces in some situations because its convex surface can ride and index directly on the concave surface being shaped, whereas the more common concave gouge must be tilted at an angle on its axis to cut, with less precision.
Since this chisel can cut parallel to its axis, and does not need to be angled up from the surface being worked to cut, it can cut and carve in much tighter locations than standard gouges.
If you need to make curved cuts at 90° to the workpiece’s surface, as in the photos above, then this chisel is indispensable. I’m sure you can see why this chisel is a must-have for the elegant ” round work” the Japanese love so much.
Another advantage is that the sloped cutting edge can easily make undercuts, something their Western counterpart cannot do. This is an essential performance criteria for accomplishing a few traditional Japanese architectural details such as the edge detail in the beam nose shown in the photo below. Good luck cutting that with a standard gouge!
It’s always nice to have the right tool for the job at hand.
Standard sizes are 9mm, 12mm, 15mm, 18mm, 24mm, 30mm, 36mm, and 42mm.
“Along with the milk of my nurse I received the knack of handling chisel and hammer, with which I make my figures.”
In a previous post, we looked at various types of oiirenomi (bench chisels) and mortise chisels. In this post we will examine a type of tatakinomi called the “Atsunomi.”
The ”Atsunomi, ” written 厚鑿, translates to “thick chisel.” This is the largest variety of tatakinomi and is almost identical in design to its petite oirenomi sisters. Being larger, heavier and stronger it is able to transmit and endure the impact forces of heavy hammer blows from sunup to sundown and cut a lot of wood. Indeed, I can remember times when the handles of the 24mm and 30mm Kiyotada atsunomi in the photographs on this page became seriously hot after long hours of heavy hammer blows.
The 24mm chisel in the photograph below was the first atsunomi I owned. All three of the Kiyotada atsunomi chisels shown herein have seen hard use with heavy hammers, but have held up well.
If I can liken the bench chisel or oiirenomi to a 1/4″ cordless hand drill, then the atsunomi is a 9 amp 1/2″ corded drill (when combined with the right steel hammer). Serious business indeed.
The atsunomi is ideal for heavy work such as timber framing and wasting large amounts of wood quickly. However, carpenters are not the only trade to use them. Many professional craftsmen in Japan, even those that never work on construction sites, prefer to use atsunomi even for delicate work because of their relatively longer blades, greater durability, and cost-effectiveness.
Because of its greater size and weight, the atsunomi is not as nimble as the smaller varieties of tataki nomi and demand greater strength and skill of the user. But on the other hand, it is very stable in the cut and wastes wood with oodles of gravitas.
As with all tataki nomi, the handle is big enough to use with one hand, but not two. Atsunomi always have a mild steel katsura crown installed at the end of the handle to reinforce it and prevent it from splitting under hammer blows.
Standard widths for atsunomi are: 12㎜, 15㎜, 18㎜, 21㎜, 24㎜, 30㎜, 36㎜, 42㎜, 48㎜.
There are several varieties of atsunomi, some with very wide blades and others with very long necks, but I will not go into that level of detail in this post.
In Part 9 of this saga of romance and derring-do, we will examine the Uchimaru Nomi.
“You can complain because roses have thorns, or you can rejoice because thorns have roses.”
This tool is a specialty mortise chisel with two blades for cutting twin mortises at the same time. It was developed specifically for cutting mortise joints in wooden stiles and rails for doors, shoji, cabinets and other joinery.
Interestingly, double or twin tenons are not called ” nihon hozo” (hozo means ” tenon”) but “ nimai hozo “ (二枚ほぞ) with “ni “ meaning 2. In this case the number is combined with the counter “mai “ used to count flat things like a sheet of paper or tenons. Japanese is almost as messy as English… I blame those pesky Buddhist priests for the complications involved in reading and writing Japanese, but I’m not sure who to blame for English.
The name is a variation of the name of the standard mortise chisel ” mukomachi nomi” in my previous post, and no, I still don’t know what it has to do with ” waiting over there.” In front of this is added ”nihon” (二本) with ” ni” meaning ”2” and ” hon” being a counter for longish things, like pencils or trees, or in this case, blades. The word is pronounced ” knee hone.”
Allow me to wander off the path a bit and talk about the Japanese language since you might find a few details interesting. If you don’t feel international today, please feel free to jump over the next few paragraphs.
The nation of Japan is called “Nihon” or “Nippon “ in the Japanese language and is written with the two characters “Ni “ 日 and ”Hon” 本 sometimes pronounced “pon.” Yes, the same pronunciation and one of the same characters used in nihon mukomachi nomi. Besides being a counter for pencils and trees and longish things, it also means ” book” and ” source. ” The word for the nation of Japan means “The source of the sun,” a jab by the Japanese at an arrogant Chinese emporer some millenia ago.
Spoken Japanese is not that difficult for English speakers to figure out, but the reading and writing are crazy difficult because of the vast quantity of Kanji, the multiple pronunciations possible for most of them, and the multiple meanings attached to many.
Elementary children are required to learn 1,006 kanji characters along with the various meanings and pronunciations. In total, a minimum of 4,272 characters are used in newspapers and magazines and must be learned before graduating middle school. Most educated people in Japan can read well over 6,000 of the over 13,000 registered kanji in Japan. Universal literacy requires a lot of study and memorization at a young age. This should give you an idea why education is so highly valued in Japan.
When I was a young missionary in Japan in the 1970’s, I spent several months stationed to Ehime prefecture in rural areas of the island of Shikoku, back when many farmhouses in that locale still had thatched roofs, no glass windows, and no electricty. Many of the older residents had spent their entire lives on their little farms and could not read or write, and had never seen a brown-haired blue-eyed foreigner before.
But the children in these mountain villages were always excited to see a foreigner and would swarm around and ask us where we were from. My standard response to this somewhat rude but innocent question was to point down at each of my legs and count them saying ”One leg, two legs. I’m a Nihonjin.” The “nihon” I was was jokingly referring to was the same as the mortise chisel which is the subject of this post, not Japanese Nationality which is pronounced identically.
Now you know a stupid pun in Japanese, so never say you didn’t get your money’s worth at this blog!
The twin-blade mortise chisel is exceptionally difficult to make, and even new ones require the owner to perform a significant amount of tuning to convince them to perform well. They have never been common, and I am not aware of anyone forging them now.
The twin tenons this chisel specializes in cutting are almost twice as strong as a larger single tenon, and are the preferred joint for high-stress wooden connections worldwide, especially joints in doors and windows. If you haven’t tried them before, you should. They look pretty cool as through tenons too.
Twin tenons have three advantages that justify the extra work. First, while they may have the same or even less cross-sectional area, they have more surface area than a single tenon in the same space, creating greater friction when assembled, if properly cut, creating a joint that is much more likely to stay assembled when stressed.
Second, this larger surface area also means a larger glue area, a big advantage with the right glue.
And finally, twin tenons are much more resistant to twisting, an huge advantage for highly stressed joints in operable doors and windows. This is their biggest advantage and is nothing to sneeze at. If you want a door to last, always use twin tenons, at least at the bottom rail.
I purchased one of these chisels many years ago. They are difficult to tune. But even after all that work, the gentleman I learned tategu work from many years ago was not impressed with my clever tool insisting that a regular mortise chisel does a better job. There is an obscure structural reason why this makes sense, which I will not delve into here, but I did not ask Mr. Honda at the time for an explanation because it would have been improper to question a master who had been a professional joiner at his level for 60 years.
I can’t get these chisels made anymore, and know of no blacksmith that makes them nowadays. The time is not far away when handmade tools will not be available except as collectors items.