Hand Tools #6 - Japanese Woodworking Tools - Part 1: Gauges, Knives & Hammers

Over the past thirty or so years, there has been a burgeoning interest in Japanese woodworking tools and methods by Western woodworkers.

We are attracted to these tools for a myriad of reasons. For some, it is the attraction of the philosophy and tradition of the Japanese woodworker or the technical aspects and quality of the tools, for others it is the romanticism of the eons old history of the Japanese sword and blade makers.

Japan is a country of very long traditions, where hundreds of years of accumulated knowledge and experience are passed down from master to apprentice, and from teacher to pupil. Every Japanese tradition has it's own set of rules and procedures. 

We have remarkable woodworkers like George Nakashima and Toshio Odate and others to thank for bringing Japanese tools and techniques to the fore in our Western woodworking, and a growing number of Western woodworkers contend that the Japanese tool design in superior in many ways.

Just in case you ask, no I am not donning my Ninja slippers, burning incense and starting to sit on the floor to do woodwork!

I love my Western hand tools, I grew up with them, their techniques and idiosyncrasies, but I do use Japanese saws, marking knives and planes on a daily basis in my workshop along with their Western counterparts.

For the true Japanese woodworker, workshop life is more of an all encompassing philosophy than just the tools. He respects and cares for his tools, almost to the point of reverence.

A Japanese craftsman or artisan is called a “Shokunin” This is not merely a descriptive title, but has a much deeper, more significant meaning. Japanese apprentices are taught that being a Shokunin not only implies having technical skill, but also implies having an attitude and social consciousness within their work.

To quote the great Toshio Odate:

The Shokunin demonstrates knowledge of tools and skill with them, the ability to create beauty and the capacity to work with incredible speed. The value of an object is dependent on a subtle combination of skill and speed; this is what the apprentice's master and his colleagues teach. This is what the Shokunin believes. Such teaching is basic and continues to be significant from the earliest stages of apprenticeship through to mastery of the craft.The pride of the Shokunin is the simultaneous achievement of skill and speed, one without the other is not Shokunin”.

Note the finger positions of the hammer hand

The Shokunin also has a social obligation to work his best for the general welfare of the people. This is both a spiritual and material obligation. Interestingly, the worst insult that you can give a Japanese craftsman, is to call him a slow worker!

In this blog entry, I cannot hope to elaborate on the entire concept of Japanese woodworking, as I am most definitely not qualified to do so. Here, I will rather concentrate on the tools that have made their way into our Western woodwork workshops, especially those that are easily available to us in South Africa.

There are a few fundamental concepts that separate Japanese woodworking tools from the Western tools that we all know and grew up with.

The basic principle of Japanese woodworking tools is that it is more efficient, accurate and productive to use a pulling motion rather than a pushing motion, when using hand planes or saws. It makes sense. Not only is it more efficient, but the process of starting the cut “away” from your centre at the full extension of your stroke, allows you to set up the stroke for the best balance. By cutting towards your body, you are bringing the tool into your centre of balance and gravity which has the remarkable advantage of more control of the tool, coupled with less effort and therefore, more efficiency.

Japanese Planing Competition

I have proved on many occasions, when teaching new woodworkers, that students develop efficient and accurate control over the tool much faster with a Japanese saw or hand plane than with it's Western counterpart. When learning to edge-joint timber with a Western hand plane, new woodworkers will invariably start the plane at 90º to the timber and the longer the board the more acute or obtuse the cutting angle will become. I think that this has to do with the following:

Western Plane – You start at your “Balance Centre” and move away into a position of less control during the cut.

Japanese Plane – You start “Away” from your “Balance Centre”, the position of least control, you then line up your body with the cut and bring the plane in towards your centre of balance and gravity. Effectively, at the point of least control (extension), you are static and setting up the cut.

A good way to test this hypothesis for yourself is to take a well sharpened and tuned Western hand plane, turn it around and do few cuts with it in the “reverse” or “pull stroke” position. You are likely to find that your cut is closer to 90º to the face of your board over a longer area of the cut than with the plane in the “push stroke” position. You also will tend to position your head and shoulders lower during the cut, compared to the position you would hold with a Western hand plane, and I strongly believe that this definitely helps with keeping the plane at 90º to the work.

The Tools:

"Keshiki" - Japanese Marking Gauges

Keshiki are available in many different sizes to suit the work at hand, much the same as in Western woodworking.

They are dissimilar to the traditional Western style gauges in that they all use blades instead of pins, to create the scribe line both with and across the grain.

As we already know, a blade will always leave a finer and cleaner line than a pin, because it cleanly severs the wood fibres, instead of scratching or tearing a line into the wood. In addition to this, there is no need to angle the marking gauge during your scribing process as one would do with a Western pin type marking gauge to avoid tear out, because the blade is bevelled. Just like many other Japanese tools, the Keshiki is used on the pull stroke, never on the push stroke.

All Keshiki are adjusted with a small Japanese hammer, either tapping the beam inwards or outwards.

These are fine instruments and are not just a wooden handle with a chunk of steel on one end.

The actual striking surfaces of the steel heads are selectively hardened. This results in part of the energy of the recoil being absorbed by the core of the head, which is made of softer steel than the striking surfaces. With this extremely clever usage of hardening, a resulting hammer blow is infinitely more effective, partly because less of the energy of the recoil of the blow makes it's way down the shaft to your wrist. Traditionally, the shaft of the Genno is shaped from Japanese White Oak which has excellent shock absorption characteristics.

Both square and octagonal Genno heads have one flat striking face and one that is slightly convex in shape. The two heads are used for different purposes, depending entirely in the job at hand. The flat striking surface of a Genno is used for tapping chisels, setting Japanese planes and for driving nails that are very close to the inside edge of a workpiece. Because the cheeks of the Genno head are parallel to each other and are at exactly 90º to the striking faces, the result is that one of the cheeks is used to bear on the one surface of the workpiece, so that the striking surface connects with the nail square on. This allows you to tap in small nails absolutely straight, even if the location is rather awkward. Simple, yet very clever! For setting nails, you would use the convex striking face of the Genno, allowing you to greatly minimise the risk of damaging the surrounding surface of the wood.

Kiridashi - Japanese Marking Knives

Japanese marking knives, called "Kiridashi", are fashioned by techniques that were originally developed for making Katana (Samurai swords) over 1200 years ago.

The lamination line of the two steels is clearly visible

Traditional Japanese Kiridashi are created in the same way that their remarkable chisels and plane blades are made. The exceptional edge is achieved by laminating very hard, high carbon steel to a softer steel. The high carbon steel that is used is not very thick, and due to the carbon content, is quite brittle. The only way that this material can be employed without snapping under force, is to forge it onto a softer, "gentler" more malleable steel. This secondary steel then acts as a support for the extremely hard, high carbon steel.

The Japanese are masters at forging steels of differing tempers to each other, and this is nowhere more apparent in Japanese tools than in their marking knives, plane blades and chisels. When you take a closer look at the bevel of either a Japanese marking knife, chisel or plane blade, you will be able to clearly see the fine line showing the lamination of the two steels.

Japanese marking knives available in South Africa are all of the traditional type and style. My personal preference is the 21mm Kakuri Kiridashi, which is my "go to" marking knife.

Interestingly, I was recently asked why I would use a single bevel Japanese marking knife instead of a Western style "spear point" double bevel knife for marking out my dovetails. The logic in the question is very sensible because you register the flat rear surface of the knife on you tail board to scribe the pin board, using the two bevels for left and right scribing. The theory is that with a single bevel knife, you can only accurately scribe the left hand side of the pins..... Not at all. Due to the very shallow bevel angle of a traditional kiridashi, the large surface of the bevel allows it to act exactly like the flat rear surface as it registers to the right hand wall of the tail, allowing you to scribe the right hand side of the pin with equal ease. Some Japanese manufacturers make the kiridashi in both left and right formats for woodworkers who find it difficult to use a single bevel knife only.

Next week in Part 2 of our Japanese Woodworking Tools blog, we shall discuss Japanese saws and chisels...

Until next time, let's make shavings, not dust!