This past weekend at the Woodworking in America conference in Valley Forge, PA, I had the pleasure of sitting in on three very informative and entertaining seminars held by master craftsman Toshio Odate.  His insights helped me get a better understanding of how and why Japanese tools work they way they do.

Some of the valuable lessons I was able to learn from Master Odate include:

* He came up through the very demanding apprentice program common for Japanese woodworkers of his era.  His master was tough.  Odate told us about his early days learning how to joint a long board using a traditional planing beam.  The complicated process involves taking a step back with one leg and shifting the weight from the front leg to the back in order to create a long shaving with no hesitation. When he didn’t move his leg properly… whack.  A crack from his master in the offending leg.  Needless to say, it  didn’t take long for him to learn the craft – or learn that master knew best.  These skills are still deeply ingrained in his hands, his eyes and his muscle memory even at 79 years old.

* The Japanese plane has only four working parts (The block, blade, chipbreaker and pin) compared to the 60 plus seen in western style metal planes.  However, the simplicity of the tool doesn’t necessarily make it an easier tool to understand.  In fact, Odate told us several times that there are only four parts you can see… there are 996 more parts that can’t be seen but must work together to get the plane to perform at its best.  These include the woodworker’s senses, the material the block is made from, how the edges of the plane are shaped… it went on and on.  This is why it’s not easy to find a comprehensive ‘’how-to’’ guide that addresses every aspect of Japanese plane craft – ultimately, the woodworker must interact with the tool to make it work properly.

* Japanese plane irons are forged of two different types of steel – a very thin base of very hard steel that is too brittle to stand on its own without cracking and a thick layer of softer, more malleable steel that  couldn’t hold an edge even if it wanted to.  Why mix these dissimilar materials?  Because, the softer steel serves as a shock absorber for the harder steel… and the harder steel is capable of holding an exquisitely sharp edge. The same holds true for Japanese chisels as well…

* But, what about those hollows on the back?  I remember when I was given a set of Japanese chisels and I tried sharpening them for the first time. I wondered what I could have done so wrong to have such a dramatic uneven area on the back side.  It turns out this hollow is there for a very important reason – when you hone, you only have to remove some of the steel behind the bevel and along the sides instead of having to grind away an entire flat area of Rockwell 64 hard steel.

* But, what happens to the hollow after you sharpen the chisels or plane irons several times?  Eventually, the back side of the bevel will fall into the hollow, making the edge useless.  Here’s where the two cutters vary wildly.  The chisel’s hollow gets deeper the further away you get from the bevel.  This way, you can grind the material away to keep the area flat behind the bevel.  On plane irons, however, the hollow is a very shallow and consistent depth.  When enough material is removed to see the bevel’s back fall into the hollow, the woodworker must hold the back side of the bevel against the end grain of a wooden block and tap the beveled face with a plane hammer to push the bevel’s back side forms the new flat. After that, the bevel is resharpened to remove the ever-so-slightly deformed bevel back into shape.  Is this nerve wracking? You bet.  Has Toshio ever cracked the brittle steel while doing this?  You bet.  Twice.  His master was quick to let him know what he had done wrong…

* Why oak for the block?  The Japanese oak used for plane bodies has very elastic properties which allow the chipbreaker and iron to be seated deeply if needed, yet tapped out gently.  Hundreds of times.  Softer woods would just collapse under the pressure of the wedge being driven in, and harder, inflexible woods such as ebony would simply split.  He repeatedly inserted and removed the iron with slight hammer taps, and the plane body willingly took and released pressure.

* Oh, and that oak block should never be finished.  Master Odate told us about a plane maker who would seal the mouth of the plane with tape and pour linseed oil into the blade well. This would soak in for a week and saturate the block. Sounds like a good idea, right?  Well, what happened was that the planes would always be wicking oil out, and they would pick up every single bit of dust, grit and grime. The blocks would become pretty nasty looking, and the company folded a year later.  Just the sweat and oils from the artisan’s hands are enough to impart a rich patina.

* Even the corners and edges of the plane block were important. Most plane makers will chamfer the top and bottom edges of the sides as well as the top of the ‘front’ of the plane.  The top rear edge is always chamfered to allow a relieved surface to tap with the plane hammer in order to exert force in the right direction.  The bottom front and rear edges, however, are always left sharp, especially on smoothing and trying planes.  This sharp edge sweeps sawdust and other grunge off the board so the body can get solid contact with the surface of the board both on the cutting pull stroke and the pushing return stroke. The only exception to this rule is when a plane is being used to ‘touch up’ a cabinet, when an unintentional bump with a sharp corner could damage a previously assembled joint.

* Finally, a plane iron is expected to require five carefully prepared oak blocks during its lifetime.  As the iron wears away, the sole of the plane is carefully scraped – or conditioned – to be absolutely tuned to the needs of the iron.

While the Japanese tools do exactly the same job as their western counterparts, their simplicity gives no clue to the intricacies in the ways they are forged, built, cared for or used.  I  went to Valley Forge hoping to learn more about hand tools, and I wasn’t disappointed. With the passing of Maloof and Krenov this past year, learning directly from a master craftsman from a previous generation is something I will treasure as I keep discovering new things about woodworking.

Special thanks to Lord LQQK for the awesome photos!