Hasegawa Kosaburo and the “Classic Profile” Gennou Head

A 200monme (750gm/26oz) classic-profile gennou with a black persimmon wood handle. Notice the swollen area near the eye of this archaic design

“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”

J.R.R. Tolkien, The Fellowship of the Ring

In this post your humble servant will introduce a famous modern-day Japanese gennou hammer blacksmith and a somewhat archaic product he infrequently forged. It is our fervent hope to provide Gentle Readers some insight into the world of the Japanese blacksmiths of yesteryear.

Hasegawa Kosaburo

Let’s begin with some background about the gennou (hammer) blacksmith known as “Kosaburo.”

Hasegawa Kosaburo 長谷川幸三郎 was born Sakai Kosaburo in 1935 in Sanjo City in Niigata prefecture Japan, the third son of a pruning shear blacksmith. He married and was adopted into the Hasegawa family and changed his legal name from Sakai to Hasegawa, a tradition in Japan used to maintain genealogical lines in the case of acute male heir deficiency.

The Hasegawa family were blacksmiths that specialized in mass-producing hammer heads.

Kosaburo worked in the family business but eventually tired of factory work and began working with his adopted brother, Hasegawa Kanichiro, who later became famous for his “Hishikan” brand gennou heads. After 10 years of practical experience in both mass-producing and hand-forging gennou heads, Kosaburo decided to devote himself to the deceptively-difficult work of hand-forging high-quality gennou heads, eventually becoming independent under his own “Kosaburo” brand.

A more detailed description of Hasegawa Kosaburo’s life and work is found at this webpage. Sorry it’s in Japanese.

Here is a video of Hasegawa-san forging a modern-profile gennou with laminated steel faces, a common method worldwide when steel was still expensive. Seeing this I think you can understand how the swell discussed below was a standard feature of forged hammers throughout most of human history.

Mr. Hasegawa has since moved on to the big woodpile in the sky where he is probably cutting charcoal. His products are no longer being manufactured, of course, but even when he was active, Kosaburo products were widely recognized as the best-quality gennou heads ever produced in Japan. At this juncture, I believe Hiroki heads are the very best new heads available.

Kosaburo’s Students

Kosaburo trained two gennou blacksmiths that are still active today: Baba Masayuki (born 1949), who uses the brand name “Doshinsai Masaykui” (道心斎正行), and Aida Hiroki (born 1964), who uses the brand name “Hiroki” (浩樹).

Mr. Baba produces beautiful decorative gennou heads. Sadly, I am not fond of his products because, in my direct experience, sometimes the eyes are not true. Am I being too severe? Should I value external beauty foremost and wink at the ugly void where the handle attaches?

Here’s my thought process in the matter; You must judge for yourself. Decoration can compensate for many shortcomings, but the used car salesman’s schtick that “It isn’t a flaw, it’s a feature” doesn’t impress me, at least not in a tool as simple as a hammer head and at the prices for which his products sell. Kinda like the city slicker who paid a high price for a stunningly beautiful Arabian horse named “tripod” and justified its missing leg because it had three good ones left, and the hopping was not really that noticeable. For me, craftsmanship and functionality take precedence over decoration. But I won’t tell you what you should think because, well, that’s your wife’s job. (ツ)

Mr. Aida’s products, on the other hand, are less decorative but of accurate construction and hardness of the sort that makes the hearts of true craftsmen sing. Making a precise, properly-forged and differentially-hardened gennou head (hard face but soft body) is no mean feat. When I can’t get Kosaburo heads, Mr. Aida’s Hiroki brand are my next choice. The last I asked Mr. Aida, he had a three-year waiting list for his products. Very popular over here.

Most blacksmith’s shops are dark, dirty, smoky places like a dungeon in hell minus the demon torturers, lakes of blood, and the bitter stink of rotisserie lawyers, but when I visited Mr. Aida’s forge I found it to be neater, cleaner, and tidier than most CNC machine shops.

The Classic-profile Gennou Head

The head pictured in this article is the primary subject of this article. It’s an antique style seldom seen anymore, one that was once the standard shape for blacksmith-forged heads throughout most of the world. I like to call it the “classic profile” gennou head. It really doesn’t have a specific name in Japanese that I have been able to discover.

The polished areas at each striking face are non-functional vestiges of the laminated steel faces applied to gennou heads back when steel was very expensive.
Please be aware that, while new, this head is old-stock, at least 40 years old. Notice the eye. Not only are its dimensions perfect, but it is centered in the body and aligned with the head’s axis in both directions. Not an easy thing to do by hand in yellow-hot steel.

We have a few of these in-stock, but they are now serious collector’s items and pricey. Few were ever made in this style and I have never seen one in an auction. Please be aware that the head shown is old-stock, at least 40 years old. During those years in storage in a cardboard box the head developed some surface rust of the sort antique dealers call “patina” in reverent tones which is easily removed, but no deep pitting.

The shape is subtle. The swollen waist is a feature all hammer heads worldwide once exhibited, a remnant of the blacksmith driving a steel drift into the yellow-hot head to form the eye into which the handle’s tenon fits. Kosaburo used this same technique to create his eyes, as does Hiroki nowadays, as seen in the video linked to above.

Traditionally this swell was very roughly formed, but Kosaburo carefully hand-filed the swells to be smooth and uniform. I am told by those who know how these things are done that it is much more work to create a pretty swell like this than to quickly grind a head into the modern shape with a uniform waist and flared faces.

From a physics viewpoint, given the same total weight, the modern-style gennou head with its narrower waist and flared faces will have a higher moment of inertia, and will therefore be more resistant to twisting out of alignment during the swing. The flared faces of the modern design also have the advantage of protecting the waist from wear and scratches when the hammer is laid on the ground or on concrete. Most people think the modern design with its flared faces to be a more attractive product. I did too until I purchased my first classic-profile head.

You will of course wonder why Kosaburo bothered to even forge this strange antique-style head. I once asked the same question to an ancient joiner that used this style of gennou head. He was much senior to Mr. Hasegawa, BTW. His answer was three-fold:

First, nostalgia. Remember, he was an old dude back when I was a younger man.

Second, while you may not think so, this shape is more difficult to produce by hand than the modern style, and although it is undeniably “jimi” (地味), meaning plain, or understated, those who know the difference appreciate the subtle details of this design. Very much a wabi sabi thing, one only true craftsmen understand. Remember, ancient dude. I thought he was full of crap at the time. Not anymore.

Third, the swell allows one to use the side of the hammer to drive nails or bang wood in tight spaces. Finish carpenters, joiners and cabinetmakers have this need, as I know from my days in the business. Many Western claw hammers have this ability, but the modern-style gennou head simply doesn’t.

So we have nostalgia, aesthetics, and functionality as factors. As far as I’m concerned, that’s a home run, baby!

This was once the standard profile for gennou heads in Japan, but sometime in the late 1890’s, I am told by people who study these things, and perhaps due to the direct influence of an exceptionally talented master blacksmith named Chiyozuru Korehide, the modern profile head with the flared ends and lacking the swell around the eye became popular.

Any old-fashioned styles that appeal to you?

YMHOS

This image has an empty alt attribute; its file name is 1956-ford-f100
Nostalgic, aesthetically interesting, and functional.
Nostalgic, aesthetically interesting, and functional.

If you have private questions or would like to receive information about our tools, please use the contact form located immediately below. Or you can view this link to our pricelist and photos of this gennou head. Please share your insights and comments with everyone using the form located further below labeled “Leave a Reply.” We aren’t evil Google, incompetent facebook, or thuggish Twitter and so absolutely will not share, sell, or profitably misplace your information. That would be theft. Cross my heart and hope to die.

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