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The truth about Japanese chisels

while Japanese chisels as woodworking implements have existed for centuries it was perhaps the makers of the famed samurai swords that have given us the chisels that we have today in this video I'll share that forgotten story and I'll help decode the fascinating technology that make Japanese woodworking chisels so different from western style chisels by the end of this video you'll have a whole new respect for the strange little tool with the dented backside let's begin back in the days of the ancient Samurai a highly respected class of Warriors that are perhaps most recognizable to Western cultures today by their legendary swords the makers of those swords were as respected as the samurai themselves they dedicated their lives to their craft often employing secret forging methods developed and passed down over Generations apart from the nobility and the samurai themselves only the makers had sufficient status to legally carry these swords but that era came to an end when the samurai class was abolished in the latter half of the 19th century and facing the prospect of unemployment many of the Great Sword makers adapted their technology to crafting other tools including chisels that Heritage is one of the main reasons why Japanese woodworking tools quickly gained a reputation as among the best in the world the goal of the Japanese tool maker was to create nothing you see a Cutting Edge is the point where two planes meet in the case of a chisel you have the sloped bevel which meets the flat back to the naked eye that may appear perfectly crisp and sharp but if you were to zoom in with a microscope you'd likely see something like this a rounded overhead it might feel sharp but it's not perfect Perfection would require those two planes to continue past that blunt Edge theoretically the steel would get thinner and thinner until the edge becomes nothing at all getting as close to nothing as possible is what the Japanese Masters spent centuries developing materials and techniques to achieve if the steel was too soft it would deform and roll over along that microscopically thin Edge you simply wouldn't be able to get such a chisel as sharp as you could with harder steel but if the steel was too hard it would be brittle and that Ultra sharp but also ultra thin Cutting Edge would just crumble away finding the right Alloys forging using the right process at the right temperatures with the right tolerances is very precise work and while many of the Japanese chisels we find in woodworking supply catalogs today are mass produced rather than handmade one at a time by an old master much of the old technology still exists including some of the best steel out there Japanese tool steel is complex but for the sake of our discussion of chisels it can be broken down into two main types what's called white paper steel and blue paper steel the blue steel is the hardest it'll take the sharpest Edge and remain sharp the longest in fact there are variations of blue steel with different contents that are even harder including super blue that might take your Edge closer to nothing than any of the Old Masters ever dreamed but blue steel can be very expensive up to several hundred dollars a chisel for certain varieties and with that extra hardness comes some real downsides it can be difficult to sharpen and it can be quite brittle and prone to chipping so the edge doesn't last that may be fine if you work with a lot of soft Woods as they certainly do in Japan but for harder woods they require a slightly more forgiving steel that's why many of the Japanese chisels you find today are made from white paper steel now this is still quite hard compared to some Western chisels and again there are different varieties of white steel with different properties but it is generally easier to sharpen a white steel chisel than a blue steel one and while the White Steel may not take quite as Keen an edge as the ultra hard blue that edge won't be as brittle and short-lived of course when I speak of blue and white steel I'm not talking about the entire chisel blade Japanese chisels incorporate another bit of useful technology blade lamination if you look at the bevel you see two different colors the bulk of the tool is made from a softer steel while a piece of harder steel is fused to the underside during the forging process obviously this lamination technique saves cost and steel but that's not its main purpose some Japanese steel is so hard it may crack or shatter when you strike the Chisel with a hammer against a hard wood the softer body absorbs the shock while the harder Underside provides the superior Cutting Edge the Dual layers also make the Chisel easier to sharpen since two-thirds or more of the bevel is soft steel that is much easier to abrade with a stone than hard steel would be perhaps the most striking feature of a Japanese chisel though is the bag notice how it's dished out this is another bit of Technology with a specific purpose when you're pairing or mortising the back of the tool becomes your reference surface it must sit flat on the wood if there's a lump on the back of your chisel The Cutting Edge is not going to work properly with western style chisels we typically flatten the backs as soon as we get them out of the package that shiny flat surface doesn't have to extend down the entire back of the tool but an inch or so from The Cutting Edge will give you the reference service you need remember though that Japanese chisels particularly the backs of them are often made from very hard steel and sometimes it just takes forever to flatten the entire thing so long ago Japanese tool makers began intentionally creating Hollow or dished out bags this makes it possible to produce a flat reference surface around the perimeter of the blade if the area behind The Cutting Edge at the tip the two edges and to a lesser extent the heel are all on the same plane the Chisel will function properly with much less work but don't confuse this with this this was a new western style chisel I showed in a recent video about flattening chisel backs with sandpaper the back of that chisel was dished out as you can see by the dullness in the center after I rubbed it on a stone but that wasn't an intentional feature created by a manufacturer as it is on the Japanese version that Hollow was inconsistently formed remember I need a reference surface at the tip and along the edges and to a lesser extent the heel so as I try to gain that by rubbing the back on sandpaper to wear it down a bit the hollow changes shape it gets smaller but it still clings to one Edge that's because it wasn't consistently formed like the hollow on the Japanese chisel so I end up having to remove almost all of the hollow to establish my reference surfaces around its perimeter and the end I just decided to polish the hole back but that's not required with a Japanese chisel which has an intentionally created carefully centered and evenly sloping Hollow o

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