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Thread: Japanese hammer/genno

  1. #1
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    Japanese hammer/genno

    I find myself using Japanese chisels more and more, and furthermore, using them with metal hammers. With timber framing, this meant my 16oz estwing hammer. With the bench chisels, I have an old ball peen hammer. I started to look at gennos of various weights, but these things are freaking expensive. Even used hammer heads in the 300-500g range are $100+. Is there much practical difference in different makers/price levels? Am I just as good to stick with my current crop of hammers? Interested in the views of people with genno experience.

  2. #2
    There are cheaper brands out there I have a Dogyu brand gennou that cost me (IIRC) somewhere between $20-30 last year. I like it. Good balance. Has a domed face on one end of the head and a flat face on the other. I'd love to have one of the hand-forged ones (I think there's enormous value in helping support the continuance of traditional methods of manufacture), but I can't justify the cost right now.

  3. #3
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    i'm a wooden mallet guy myself and have made them in a variety of weights. One does not serve for all tasks. Would I go to metal, a few antique cobbler's hammers would be on my Christmas list, with big flat faces close to the center of the handle. Making personalized handles would be a nice winter project.

  4. #4
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    Whether it would be worthwhile for you to get a high-quality genno head and make your own handle for it will depend at least to some extent on how sensitive you are to feedback and efficiency.

    Stan Covington has a good quantity of information on his website (covingtonandsons.com). As Stan notes, for the head itself the eye is of particular importance--how cleanly formed is it, how well aligned to the sides and faces, and so on. He includes detailed instructions on how to make a traditional handle that is customized for your hand and arm. A high quality genno head on a traditionally designed handle will generate a solid hit with the center of percussion (the "sweet spot") at or very near the point of impact with the chisel, and makes it significantly easier to feel what is occurring at the chisel's cutting edge if you're paying attention as well as avoiding vibration of the handle in your hand. Further, a correctly designed (for your hand and arm) traditional handle will make it easier on your body--you'll generate less stress on your joints and be more able to avoid repetitive stress injuries. The flat face is also easier on the chisel handles than a domed hammer face, spreading out the impact over a greater area.

    There is a significant difference in feel, efficacy, and efficiency in chisel use between any framing or ball peen hammer I have used and a mass-produced genno, let alone a customized high-quality one; if you want to get an idea of the difference without spending a lot of money, I'd suggest purchasing a decent mass-produced genno to start, but note that a high quality genno head with a custom handle will be a significant step above this.

    I don't have experience with a variety of makers, but Stan does and he is happy to share information. He's a great guy to deal with and stands behind everything he sells. Everything I have purchased from him has been exceptional. I have never regretted taking Stan's advice.

  5. #5
    Well, I used sledge hammers for years when doing concrete work. When it comes to chisels, I don't like hammers or mallet style wood hammers either. I prefer the fish bonker type of mallet. There is one guy on You Tube I like to watch, H Carpenter, and he uses the end of an old baseball bat. I can hit the head of a chisel with a hammer, and not have to look at the handle, but the long mallet style just works better for me.

    robo hippy

  6. #6
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    Michael, that is helpful. It is what i was looking for, that these hammers are slightly better/improved. Also, i can get behind you are paying a premium simply because its a handmade product and not that its necessarily 'better' from a functional standpoint. They are still a little wild to me that these are routinely $200-300 per hammer head. Makes me wonder if i can do justice to the hammer head with my handle making abilities!

  7. #7
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    If you dig a bit into what it takes to make a high-quality genno head, you'll soon see that the smith is not earning an exorbitant hourly wage even at $200-300 per head. Are you paying for skill? Absolutely. A high level of skill costs more per hour, as with any profession. Will it be better than a mass-produced genno head? If you choose a reputable seller, it will.

    If you follow Stan's instructions, it's not difficult to do quite a bit better than a mass-produced genno even if the handle is "terrible" compared to, say, Stan's level of skill. As Stan notes, the head will outlast the handle; the second handle will be better than the first, and if there's a third it will be even better. If there's anything you don't like about your first handle, build another using the lessons you've learned and replace the first.

    You can do it!

  8. #8
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    There is an article on making handles for a gennou on my website: http://www.inthewoodshop.com/ShopMad...oraGennou.html

    Those handles were eventually remade a couple of times until I achieved a comfortable diameter. The current two I use are



    375g (upper) and 225g (lower) heads. I use the 225 mostly, and the 375 when morticing.

    Regards from Perth

    Derek

  9. #9
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    Excuse my 'ignorance' - but up here way above the 'moral' ( arctic) circle, most people I know haven't heard of japanese tools, neither seen a picture of one..
    I have had my pull saws for quite some time, and I'm concidering buying a few wide chisels... but except for 'coolness' , what's so special about the gennou hammers?? While I fully understand the weight and balance thing, which also applies to other types of tools, what is it about these hammers? Hardening of the head? Other aspects??
    Last edited by Halgeir Wold; 09-24-2022 at 5:04 PM.

  10. #10
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    This is a quote from So Yamashita’s website. So lives on the northern beaches of Sydney and sells the very highest quality Japanese tools. I obtained my gennou heads from him many years ago.

    A bit more on Japanese hammers, since I started (^^). Top quality handmade Japanese hammerheads are not hardened just evenly throughout the body. The hardness is different within a single head. The centre of the striking surface is softer so that it won't be as slippery when striking the nail. The peripheral is made harder to prevent dents and chips. The body is hardened and tempered to make it as tenacious as possible to absorb the shock. The best of the best hammerheads are constructed using soft iron for the body and steel laminated on the striking surface. The MOST expensive ones even have wood grain pattern on the jigane (body iron). The handle attatching hole is opened to absolute square, and the center is made slightly tighter by tapping the body from outside after the hole has been gouged. This makes it possible for the handle to be attatched with no wedge holding the handle from the other side, and still will not come off. The best made hole's edge is not rounded at all, and it looks as if it was chiseled out.


    Japanese gennous aren't just a chunk of steel with a hole in the middle. It has a microcosm in itself.ore on
    Japanese hammers, since I started (^^). Top quality handmade Japanese hammerheads are not hardened just evenly throughout
    Regards from Perth

    Derek

    A bit more on Japanese hammers, since I started (^^). Top qualitping the body from outside after the hole has been gouged. This makes it possible for the handle to be attatched with no wedge holding the handle from the other side, and still will not come off. The best made hole's edge is not rounded at all, and it looks as if it was chiseled out.

    Japanese gennous aren't just a chunk of steel with a hole in the middle. It has a microcosm in itself.

    Last edited by Derek Cohen; 09-24-2022 at 8:01 PM.

  11. #11
    I was wondering what the weight was, and the heavier one above is about a pound. That would be adequate, and not too heavy. I picked up a set of carving chisels which had a persimmon mallet with them. It is about 4 inch diameter and just too heavy. When doing concrete construction, I started with a 32 oz. hammer. I ended up with a 20 oz. hammer. That is just too much weight to be swinging around, except for driving stakes. 10 pound sledge....

    I am curious about what weights you all prefer????

    robo hippy

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