SHARPENING… Again, merciful heaven !
OK so i’ll dip my toe in this murky pool. But only because my buddy on the blog asked me to do it. He says “How do you sharpen Japanese chisels?” Well the answer is really pretty much the same way you sharpen European blades. We begin with getting the back of the blade absolutely flat. We use a one eighty wet and dry abrasive on a dead flat granite surface. Followed by three hundred then one thousand then six thousand grit Japanese water stones. Keeping the Japanese water stones dead flat in this process is absolutely of paramount importance.
Why do we bother getting the back of the blade flat? Well it’s to make sure that you have absolute contact with those sharpening stones. The most important part is when you’re working is the corner of the blade. That seems to do 90% of all work. Especially when pairing, chopping’s another matter. So get that back flat, polished and shiny. If you can hold it away at arms length and see your eyeball a yard away then it is about right. If you can’t then something’s wrong.
Next we grind our blades to twenty-five degrees. This is a general all round all purpose grinding angle. Pairing chisels maybe ground slightly lower and chopping blades slightly higher. But this is the general all purpose. Grinding we do on a Tormac water stone, or, if you know what you’re doing, on a bench grinder. We don’t use slowed down special grinders but we do form the surface of the grindstone with a diamond stone to a slight dome. So that the stone is only cutting one spot. That way by moving the blade across the grindstone we can keep the edge cool. Our grinder is also setup with a workshop made tool rest which just helps us locate the tool and present it cleanly to the grindstone and move it around easily in front of the stone.
HONING THE MICRO BEVEL
The Japanese hone the entire surface and most of the Japanese blades are ground at an angle of thirty degrees. This is too high for Western work and I think honing the whole of that surface is a waste of time. We just hone a micro bevel on the front like we do all our European blades. We hone without honing guides, again, because of speed. I know this is fighting talk but at Rowden we wouldn’t employ anybody who has to use a honing guide to sharpen blades.
NO TRAINING WHEELS AT ROWDEN
It’s a different matter, however, if you’re not doing this work to earn your living, then just don’t worry about it, take your time, use what jigs you need and get it right.
Honing we do on a one thousand grit Japanese water stone and then we’re just pulling to turn a burr. That burr is then polished off by honing with probably a four thousand or six thousand grit water stone. I doubt if we took it any further at this point for a chisel. Japanese plane irons maybe we take it to a finer grit maybe ten or twelve thousand. But a chisel, four or six thousand seems to be OK.
LITTLE AND OFTEN
The essence of the technique is little and often. We don’t worry too much about buying chisels that hold their edge forever because our attitude in this workshop is to, when your concentration breaks after ten or fifteen minutes of detailed work, you raise your eyes from the bench, blink and just walk over to where the sharpening bench. Touch up that blade in your hand. The blade never gets blunt. You’re always keeping it in that really sharp, keen area. Sharpening in this context takes a minute, minute and a half. Don’t begrudge doing it little and often.