Trizor XV on balanced 70/30 blade???

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Joined Aug 5, 2021
I've recently purchased my first good knife, a Fujiwara Kanefusa Molybdenum Japanese Chef's Western Deba. The blade edge is described as double edge, 70/30 balanced.
The knife is not sharp, something I've read that is not uncommon for Japanese knives. I'm a bit confused about how to best sharpen it. I'm not keen on getting wetstones and struggling with that process. I'm thinking about getting a Trizor XV because it puts a 15 degree edge, which is what most Japanese knives are supposed to have. But the 70/30 figure confuses me. Will I ruin the blade if I use a 15 degree Trizor sharpener on it?

Thanks

 
144
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Joined Nov 18, 2010
You better follow the existing geometry, letting the right bevel form a continuous arc with the right convex face, and do whatever is needed on the left side to counter clockwise steering. That will often be a straight bevel at a much higher angle to balance friction on both sides. Please be aware of the edge being strongly off-centered to the left. So, there's much less friction on the left side: that's why it will tend to steer clockwise. The solution is increasing the left side friction and reducing it on the right side, by thinning behind the edge. It isn't easy, especially with a thick knife like a Western Deba, where the smallest asymmetry is amplified — with a laser you would hardly notice it. Don't forget to loosen your grip. Some day, you will be able to compensate for steering by the way you hold the knife. But for now: putting a symmetric V-edge on it will cause
crazy steering and poor performance within a few sharpenings.
 
159
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Joined Jun 7, 2021
double bevel, 70/30 means it is first sharpened with a 30 degree bevel on one side, and a 70' bevel on the other The 70' side provides lots of metal, which resists edge curling, and adds strength to the cutting edge.. The knife is strong enough to chop through small bones, and gristle. Sharpening at 15' will not sharpen the edge, as the thicker 30, and 70 degree angles will prevent contact with the edge. Over time, it will weaken the cutting edge of the knife. This knife is meant to do serious work. It won't cut sushi, or paper thin tomato slices. For a more useful, all purpose chef's knife, look for good steel, and a convex bevel. It is both a stronger, and more versatile edge.

Seeeeya; Chief Longwind of the North
 
144
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Joined Nov 18, 2010
70/30 hasn't much to do with angles. It gives some indication of how much the edge is off-centered, normally to the left with a right-biased blade meant for right-handers. The edge being off-centered, it will steer unless you compensate both by handling and by the edge you put on it. The friction on the right side is much higher than on the left, so it will steer clock-wise. You may compensate somewhat by thinning the right side behind, and by increasing the sharpening angle on the left side.
It's common to see well balanced strongly asymmetric blades with a convex right bevel who forms a continuous arc with the blade, ending at some 10-12°.
On the left side I would find out whether a straight bevel of some 15-18° makes the steering acceptable to you. It is quite a personal matter. The way you hold the knife will affect the steering, with a loose grip and a slight slope you will further reduce it. And you simply get used to cutting straight with an asymmetric blade, but it takes some time.

 
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