Tool Focus: Japanese Nomi Chisels

The answer lies in the clever construction process used by the Japanese tool makers that allows their chisels to hold a sharper edge:  techniques developed by Samurai sword makers that have been passed down to and refined by successive generations of blacksmiths.  The process is so involved that apprenticeships last for 10-15 years and many chisels bear the names of the master blacksmiths that produced them.

Steel has one limiting factor:  it must be sharp in order to cut effectively, however the harder you make steel the more brittle it becomes.  The difference between Western and Japanese chisels is that the latter have bi-metal blades, with an extremely hard tool steel for the cutting edge with a softer steel forge-welded over the top which allows the blade to flex – acting as a sort of suspension.  It also means that they can hold a sharper edge with a shallower angle of attack on the cutting edge of the blade.  Western chisels have a single metal blade and therefore there is a point at which any further increases in hardness will make them un-useably brittle.  Just as the famous swords of the Samurai warriors were held in high regard for their quality and sharpness, so do modern Japanese woodworking tools such as the Nomi chisel.

We use chisels for all sorts of fine joinery tasks whilst making our hollow wooden surfboards, but most frequently it is for neatening up the ends of the rails ready to take the nose or tail blocks.  An awful lot of the time they sit there on the tool wall, but when we do reach for one we’re glad that we have the sharpest tools made by master craftsmen drawing on generations of experience and expertise.