By Wilbur Pan
Japanese tools have a reputation of being suitable only for softwoods. This is an unfounded worry, especially in the case of Japanese chisels. As woodworker Kari Hultman (writer of The Village Carpenter blog) attests, “I would like to publicly profess my love of Japanese chisels. All the rest of you chisels can just go home now. I have used the same chisel for chopping and paring maple for days and days and have yet to resharpen it.”
Experience, and knowing what underlies the construction of a Japanese chisel, will empower you to use these chisels in any woodworking task.
Japanese chisels can take an extremely sharp edge that lasts a long time, due mainly to the treatment and type of steel used for the cutting edge. This tool steel typically has a higher carbon content and relatively few alloying elements compared to Western tool steels. That leads to a higher carbide content in the finished Japanese chisel than in Western chisels.
Today, the most common steels used are “white steel” and “blue steel.” The names come from the color of the paper used to package these steels, which are manufactured by Hitachi. The main difference between the two is that blue steel has alloying agents added that give it added abrasion resistance and a more durable edge. But white steel is easier to sharpen, and also can have a durable edge. This is somewhat like the difference between O1 and A2 steels.
The steel in Japanese chisels is hardened to a higher degree than most Western chisels. Japanese chisels with a Rockwell hardness of 64 or higher on the “C” scale are not uncommon, whereas Western chisels typically have a Rockwell hardness of 60-62. The added hardness results in the edge being less likely to deform under impact, such as when chopping.
Japanese chisels also undergo a forge-welding process in their manufacture. The repeated hammering in this process causes the carbides that are in the steel to become very small and evenly distributed, which results in an extremely sharp and long-lasting edge.
But as Milton Friedman said, there’s no such thing as a free lunch. Having a very hard steel that can take a very sharp edge comes at a cost, and that is brittleness. If an entire chisel were made of a very hard steel, it’s very likely that the chisel would snap under use. That is one reason why Western chisels aren’t often hardened past a Rockwell hardness of 60-62, because O1 and A2 steels can also become brittle if they are treated to be very hard.
■ router base for Foredom Flex Shaft , $135
■ set of 3 bits (1⁄32″, 1⁄16″, 1⁄8″($35.95)
luthiersupply.com or 541-603-5049
■ wide variety of shell blanks and pre-made inlays
rescuepearl.com or 530-676-2270
■ shell blanks, pre-cut designs and a wide array of reconstituted stone
riogrande.com or 800-545-6566
■ Epoxy 330
■ graver handles and sets of needle files
Blog: Visit Wilbur Pan’s blog for more on Japanese tools and woodworking.
In Our Store: “Japanese Saws vs. Western Saws,” an article by Christopher Schwarz.
To Buy: “Japanese Hand Tools & Joinery,” a DVD by Jay van Arsdale.
From the February 2013 issue #202
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