Sharpening Asymmetrical Edges

C

cm_bushman

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Oct 22, 2012
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I'm hoping to improve my sharpening skills and my kitchen knife collection with some Japanese kitchen knives, but I notice many have asymmetrical edges, some 60/40, others 80/20, etc. I am aware of the effect this has on cutting, but my real concern is how this makes them different/more difficult to correctly sharpen. Is there a special procedure or any tips and tricks you guys can offer when attempting to sharpen these kinds of edges? Would you not recommend them to a novice sharpener?
 
I freehand and simply match the sharpening angle to the angle on each side of the blade. If you can freehand a symmetrical grind, asymetrical grinds are no big deal.

If you're using a jig, edge pro,etc., I believe you have re-adjust the sharpening angle each time you flip the blade.
 
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I tend to think japanese knives are more for the experienced person with hand skills.
 
They are very easy to sharpen.

The angles are the same per side its just how much sharpening you do on each side. There are two basic descriptions of these edges, 70/30 and 80/20 and you can think of them as a percent.

Personally I find them very easy to sharpen, sharpen one side and deburr the other, pretty easy.
 
If you're sharpening a chisel sharpened blade (bevel on one side only), wipe the burr back into the grinding plane with a ceramic blade. Do this at the end of each grit change. After you're finished with your finest stone, lightly "steel" the knife on the ceramic blade.
 
It's not chisel sharpened its asymmetric, it has a bevel on both sides. One is just much more pronounced than the other.
 
They say it works better for food release, its easier to sharpen and it gets sharper. I can see the food release and sharpening thing but getting sharper is questionable.
 
Duh! What is food release? Why would an asymmetric edge be easier to sharpen?
 
When you are cutting the object being cut will release or stick to the blade, with a asymmetric edge the object being cut is being pushed away from the blade due to the edge being off center. With a edge that is equally ground everything flows in line making it easier for things to stick to the blade.

As for sharpening,

You are basically sharpening one side, grind until you have a burr then make a few passes on the opposing side to clean it up. You don't have to worries if the edge is off center or if you have equal bevels so you just concentrate on technique.
 
Traditional Japanese knives like a yanagiba, usuba, and deba have a single bevel edge with a Urasaki / hollow on one side and a Hamaguri / clamshell grind on the other. These need different, more advanced sharpening techniques than a double edge blade.

The Western patterns have a double bevel edge. Most have an asymmetrical grind (80/20, 70/30, etc.) edge and/or bevel that extends further up on side of the blade. Personally i don't find them any easier or more difficult to sharpen than a 50/50 grind.

Jon at JapaneseKnifeImports has a bunch of sharpening videos on YouTube that are worth checking out.
 
[video=youtube_share;dDsWh_M7Rek]http://youtu.be/dDsWh_M7Rek[/video]

This should demystify this confused topic a bit. I get asked about this quite often. It is a much simpler concept than some of the confused explanations out there.

---
Ken
 
Here's a diagram that should be of use as well. Please ask me any questions of this is confusing.

1377743700-thinningSymmetryadjust.jpg


---
Ken
 
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