Yet such is oft the course of deeds that move the wheels of the world: small hands do them because they must, while the eyes of the great are elsewhere.Elrond
This is the first article in a six-part series that condenses the advice we have given to our Beloved Customers over the years regarding the hammers they should use with our chisels. While some of this information is relevant to our warranty, all of it is relevant to how well our chisels will perform and the pleasure our Beloved Customers will enjoy using them.
In this first part we will focus on the varieties of hammers we recommend. Subsequent articles in this series will focus on appropriate hammer weights and faces, how to use a chisel efficiently, the “chisel cha-cha,” the importance of rhythm, as well as a discussion about health and hammers. There may even be a song or two to hum along with. Helluvalot better than a performance of Cats, and cheaper too.
In the future we will present several different series, one with more details about hammer heads, and another explaining why and describing how to make a handle for a Japanese gennou hammer (or any hammer for that matter), with scaled reference drawings. We will of course provide the entire contents of these articles in a single wiggling bundle to our Beloved Customers that purchase one of our gennou heads. Yes, there are more perks to being a Beloved Customer than simple toe-curling joy (ツ）。It’s a cunning plan, you see.
We sell tatakinomi chisels such as oiirenomi, mukomachinomi (mortise chisels), or atsunomi all designed to be motivated by the most efficient method available, namely a steel hammer swung by human hand and arm. I won’t debate the pros/cons of steel hammers versus wooden mallets versus plastic mallets versus brass hammers versus unobtanium-platinum alloy hammers in this post because the physics are as obvious as a lemur in a lingerie shop (they’re a bit hairy, they jump and climb all over the displays and bras don’t quite fit them right) beyond noting that a hardened steel hammer imparts more energy to a chisel in a more easily focused and controllable manner than any other type of beater considering the economics of both initial cost and repair/replacement cost. Some may disagree; A mind is a terrible thing to taste.
The advantages of the steel hammer are quite obvious, even without doing energy calculations, but are there any disadvantages? Mochiron (Japanese for “of course”).
Steel hammers can concentrate so much energy on a tool handle so efficiently and so quickly that they may eventually destroy the handles of the sharpened screwdrivers sold as chisels nowadays in Western countries due to a faulty design detail. It’s this silly design flaw most modern Western chisels share that motivates people to use softer, fatter, energy wasting mallets made of wood, plastic or rawhide. So sad.
An obvious solution is to use a steel hammer of a reasonable weight along with intelligent technique to effectively keep the energy imparted to the chisel within acceptable limits. But this may not be enough if the chisel design is weak.
Ooh ooh! I got’n idea. Why not design and manufacture a chisel that a steel hammer won’t destroy as a matter of course? Wow! Such an innovation would be right up there with the rumors I’ve heard of buggies that move without horses. Imagine that…
Fortunately, the tataki nomi chisels we sell are professional tools designed to be struck by steel hammers so they need not be coddled. They have a mild steel kuchigane (coned ferrule) fitted where the handle meets the blade, and a mild-steel hoop, or crown seated at the butt end of the handle. When properly fitted to a dense, straight-grained Japanese oak handle, this steel furniture does a great job of protecting the handle from splitting or breaking.
However, along with the handle, these parts do need to be setup properly to ensure they continue to protect the handle for a long time. We have provided clear instructions for how to perform this setup job here.
So, please use a hardened steel hammer with our chisels.
But there is more to hammers than just materials, so let’s continue onto the next subject.
Japanese Hammer Types
The traditional hammer used in Eastern Japan for striking chisels and general carpentry work is called a “gennou” pronounced “ghen-noh.”
The gennou common to Eastern Japan is a simple symmetrical cylinder of one sort or another with a flat face on one end and a domed face on the other, often called the “ryoguchi gennou,” or the “Janus Hammer” by those with a classical education. No claws, no pointy tail. The flat face is used for striking chisels and pounding nails. The domed face is used for something called “kigoroshi” and for the last stroke when setting nails. It’s a handy tool and more stable in the swing than a claw hammer. It’s a matter of physics.
Japanese carpenters use a specialized nail bar for pulling nails effectively increasing the lifespan of their hammer handles, so claws are not necessary.
The Yamakichi style gennou head (see photo below) is another variety popular primarily in Western Japan. The tail is not pointy but rather a small square face that is useful for starting small nails and for “ tapping out” plane blades. The face typically has a slight curvature which is helpful for setting nails, but not enough to damage a chisel. The moment of inertia is less than the symmetrical gennou head so it is not as stable in the swing, but it is still a fine head.
The pictures below are of a gennou head called “Funate,” which translates to “boat hand.” I have heard it originated with ship carpenters, but am uncertain. The tail end is a small square as you can see from the photo, and is handy for setting nails. It makes a great finish hammer, but as a hammer for striking gennou it never appealed to me. But there are plenty of craftsmen that love this hammer.
Any of these hammers will do the job: it’s all personal preference.
Western Hammer Types
The purpose of this article is is not to suggest that our Beloved Customers must use a Japanese hammer when beating on our chisels. In fact, nearly any variety of quality steel hammer can be easily modified to do the job satisfactorily, including claw hammers, engineer’s hammers, or even ball peen hammers, so it isn’t necessary to buy a special hammer.
Please note that the closer the hammer’s center of mass is aligned with the center of the striking face, and the higher the hammer’s moment of inertia, the better. A cylindrical head is the closest to ideal from a physics viewpoint.
We’ll talk about the governing physics of hammers in future posts for those Gentle Readers that enjoy math.
In the next post in this series we will examine the type of face a hammer used to strike our chisels should have. Please come back and bring your lingerie-loving lemur friends. A Brazilian body wax is not required.
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