Different Japanese hammers: shapes, names, and uses of the Genno

The Japanese hammer, or Genno, is an iconic tool in Japanese woodworking. But did you know that there are several shapes of Japanese hammers, each designed for a specific use? Ryoguchi, Daruma, Yamakichi, Funate… Discover the main types of Japanese hammers and how to choose the one that suits your work.

Key points to remember

• Genno (玄翁) mainly refers to Japanese hammers used in woodworking and for striking wood chisels.
• The Ryoguchi Genno is the traditional two-faced model, with one flat face and one slightly domed face.
• The Daruma Genno is a shorter, stockier version of the Ryoguchi.
• The Yamakichi Genno is a versatile model, particularly useful for switching between chisels and nails.
• The Funate Genno is more geared towards driving nails and has a tapered rear end.
• Japanese hammer shapes are not limited to the Genno: there are also Kanazuchi, forging hammers, wooden mallets, and copper or brass hammers.

What is a Japanese hammer?

In Japan, several terms can be used to describe a hammer depending on its construction and use.

The term Kanazuchi (金槌) is specifically used to refer to a metal hammer intended for striking, particularly for nailing. The term Tsuchi (槌) is more general and means hammer or mallet.

But when talking about Japanese tools for joinery, cabinetmaking, and using wood chisels, it is primarily the term Genno (玄翁) that is encountered.

The Genno consists of a steel head and a wooden handle. Its design seems extremely simple, but its shape, weight, balance, and the geometry of its faces have a direct influence on the precision of the strike.

The traditional Genno is particularly suited for use with Nomi, Japanese wood chisels. It can also be used for nailing and certain wood adjustment operations.

Specialists at Covington & Sons point out that the Genno is a special case among Japanese hammers, as it is specifically designed for striking chisels, adjusting plane irons, and performing certain wood fitting operations.

The main shapes of Japanese Genno

When looking for a Japanese hammer for joinery, four main shapes appear regularly:

1. Ryoguchi Genno
2. Daruma Genno
3. Yamakichi Genno
4. Funate Genno

There are also many variations and intermediate shapes.

Covington & Sons considers these four models to be the main Genno head shapes available today for woodworking.

1. Ryoguchi Genno: the traditional two-faced Japanese hammer

The Ryoguchi Genno (両口玄能) is probably the most iconic Genno shape.

The term Ryoguchi literally means something like "two mouths": the head effectively has two striking faces.

The first is generally flat, while the second is slightly domed.

What are the two faces of the Ryoguchi used for?

The flat face is mainly used for:

• striking Japanese wood chisels;
• driving nails;
• performing strikes that require good precision.

The domed face has a different function. It can be used, for example, for final strikes to slightly sink a nail head into the wood.

This operation is linked to the Japanese principle of Kigoroshi (木殺し), which can be translated literally as "killing the wood." It is a technique consisting of locally compressing the wood fibers to facilitate certain adjustments or joinery.

Why is the Ryoguchi so popular?

Its symmetrical head offers excellent stability during the movement.

This stability is particularly useful when using the hammer to strike a Japanese Nomi: the hammer naturally accompanies the gesture and allows for a steady strike.

The shape of the head can also vary. There are round, oval, square, rectangular, octagonal heads, or intermediate shapes.

Covington & Sons notes that octagonal or cut-angle shapes are particularly appreciated, while 90° angles may be less useful for certain adjustment operations.

The Ryoguchi is therefore the ideal choice if you are looking for a versatile Japanese hammer for joinery and regular use of wood chisels.

2. Daruma Genno: the compact and powerful Japanese hammer

The Daruma Genno (達磨玄能) is easily recognizable by its short and stocky silhouette.

Its name refers to the Daruma, the famous Japanese figurine traditionally represented with a rounded body.

The Daruma uses the same principle as the Ryoguchi, but with a head that is generally more compact and massive.

What are the advantages of the Daruma?

Its compact shape gives an impression of great stability and concentrates more mass around the center of the head.

It is particularly interesting for users looking for a highly maneuverable Japanese hammer for wood chisel work.

The Daruma is, in a way, the "stocky little brother" of the Ryoguchi: it maintains the double-face principle while adopting a shorter geometry.

It is also a particularly recognizable shape for fans of Japanese tools.

3. Yamakichi Genno: an extremely versatile Japanese hammer

The Yamakichi Genno (山吉) is a particularly interesting shape for those who want a single hammer capable of performing multiple tasks.

Its history is also distinctive.

According to Covington & Sons, this shape is named after the Japanese blacksmith Yamakichi, from Fukuoka on the island of Kyushu. The model was then supposedly introduced and slightly adapted to meet the needs of users in the Tokyo region.

A hybrid shape

The Yamakichi has a shorter, more robust silhouette than the Funate.

Its rear end is tapered and ends in a small surface that allows, among other things, to:

• start and position nails;
• work in spaces that are harder to access;
• adjust certain parts;
• perform operations on Japanese plane irons.

Its main face remains sufficiently adapted for striking wood chisels.

The Yamakichi: the "do-it-all" Genno

It is likely one of the most interesting models for a joiner who wants to carry a single Japanese hammer in their workshop or to a job site.

It acts as a compromise between the Ryoguchi, excellent for chisels, and the Funate, more geared towards nailing.

Covington & Sons presents it as an excellent versatile hammer for work in the field.

4. Funate Genno: the Japanese carpenter's hammer

The Funate Genno (船手玄能) has an easily identifiable silhouette due to its tapered rear end.

The name Funate is associated with the maritime world and can be understood in the context of marine carpenter work.

The rear part of the head is particularly useful for starting a hole or positioning a nail in certain situations.

This characteristic explains its historical interest for shipbuilding work, particularly when it is necessary to work in spaces that are difficult to access.

The Funate, however, remains usable in general joinery.

Its slightly domed striking face can, in particular, be used to strike chisels, even if this shape is generally considered to be more oriented towards nailing and assembly work than the Ryoguchi.

Ryoguchi, Daruma, Yamakichi, or Funate: which one to choose?

Here is a simple summary to help you choose your Japanese hammer.

For Japanese joinery

If your priority is use with Japanese wood chisels, the Ryoguchi is an excellent starting point.

For a compact hammer

The Daruma is particularly interesting if you like short, massive heads.

For a versatile hammer

The Yamakichi is probably the most versatile choice for alternating between chisels, nails, and adjustments.

For nailing

The Funate is particularly interesting when the work involves a lot of nails or requires a rear end that allows for their initial placement.

Other Japanese hammers: Kanazuchi, Sakikiri, and Hakoya

The Genno only represent part of the family of Japanese hammers.

There are also several specialized shapes.

Kanazuchi: the Japanese steel hammer

Kanazuchi (金槌) is a term commonly used to refer to a metal hammer.

It can be used for various DIY, construction, or metalworking tasks.

One should not therefore consider Kanazuchi as the name of a single head shape: it is rather a general designation.

Covington & Sons makes a distinction between the Genno intended for specific uses in joinery and the Kanazuchi used particularly for nailing and other striking work.

Sakikiri Kanazuchi

The Sakikiri Kanazuchi (先切金槌), sometimes simply called Sakkiri, has a more specialized shape.

Its head combines a striking face and a narrow or tapered rear end.

This geometry allows, in particular, working in places where a classic hammer head would be difficult to position.

It is particularly interesting for certain nailing and assembly jobs.

Hakoya Kanazuchi

The Hakoya Kanazuchi (箱屋金槌) is traditionally associated with the work of box makers.

Its unique feature is having an end that allows, among other things, working with nails.

In terms of function, it is closer to certain Western carpenter's hammers.

Japanese forging hammers

The world of Japanese forging also has its own hammers.

Tezuchi and Kozuchi

The Tezuchi (手槌) or Kozuchi (小槌) refers to a small hand hammer used particularly in metalworking.

In traditional Japanese forging, the geometry of the hammer is different from that of the joiner's Genno.

The blacksmith can use an asymmetrical head to better accompany the wrist movement and control the impact zone.

Ōzuchi: the heavy forging hammer

The Ōzuchi (大槌) is a much larger sledgehammer used with two hands or by the blacksmith's assistant.

It is used in particular for roughing out and shaping hot metal.

These hammers belong to a different world than that of the woodworking Genno.

Kizuchi: the Japanese wooden mallet

The Kizuchi (木槌) is a mallet with a head made of wood.

It is particularly useful when you want to transmit significant force without striking the workpiece directly with a steel head.

It can be found in particular for:

• assembling wooden parts;
• certain carpentry work;
• fitting;