A Handle On Things - Japanese Hammer (Genno, 玄能)

On Saturday I took some time for myself, I had bought a Japanese hammer in May and finally felt confident enough to make the handle for it. The man who sold me the hammer also gave me a piece of Japanese Beech ((Buna) at least I think this is what it is, still a mystery) to use as the handle.

Japanese hammers have two sides, one is flat the other is round. The flat side is for initially striking nails and the other is for the finishing strike. The domed side only compresses the wood, it does not tear it. By compressing the fibers of the wood they are given a chance to bounce back.

When assembling joinery there is a technique called "kigoroshi" where the rounded part of the hammer strikes the contact surface of the wood joint, when glue is added to the joinery the compressed fibers will expand again and make the joint even tighter.

Penciled out the shape of the handle.

Cut the shape out on the bandsaw.

After shaving the sides down to the thickness of the eye I began to push the handle into the head. Depending on the level of quality, hammers will either have a parallel opening (lesser quality) to take the handle, where the walls are straight, or the walls will have an hourglass shape (high quality). This hammer has an hourglass eye, if I make the handle exactly the size of the eye then as it goes through the wood will be compressed and slowly, but surely, push through. When through the hammer does not need a wedge to hold it, the wood was compressed and has expanded around the hourglass, holding it securely. This particular hammer was hand forged by Masayuki, currently one of the best blacksmiths in Japan that is still alive.

Fun fact, I bought this hammer for around $100USD. The man who taught Masayuki, HaKozaburo who died in 2004, his hammers go for MINIMUM four times more.

To fit the handle I hold the hammer upside down and strike it with a mallet. The inertia from the mallet drives the handle through the eye.

I managed to fit the handle a little more than halfway through the eye. I made the taper of my handle 2mm and now it is stuck with 3/8" left to go. Hindsight, I could have used half a millimeter for the taper and it would have been perfect. If the handle is a bit stuck good practice is to take a few whacks every day for a month to move the handle further in. It has been a day since I made this hammer so I hit it a few more times today and moved it 1/64". Progress.

The final product. Not perfect, but I am happy with this first attempt at making a handle. Next one will be even better.