Asymmetry – The REAL DEAL

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Can someone please comment if I'm understanding correctly?

For a typical double-bevel right-hand guyto, the right side secondary bevel is generally ground convex and with greater convexity than the left side, which can also be flat or concave.

The greater convexity of the right side improves food release. What this also results in is a force to the left when cutting through something. In order to counter this the primary bevel is ground asymmetrically as well, with the right side primary bevel at a more obtuse angle than the left side primary bevel. This also follows the secondary bevel geometry (right side more obtuse than the left side). To control steering, the goal during sharpening is to both maintain the appropriate angle for each side of the primary bevel while also keeping the edge apex centered.

I think I read the relationship between the angles of the two sides correctly in the previous comments.
 
To reduce steering to the left you may want to increase the left angle, thus increasing friction. But take care with general statements, as all will depend on the individual knife with its own properties, its sharpening history, and the individual user who is more or less used to steering and compensating for it.
 
I was guided to this thread by another member and wanted to thank Dave and everybody else for your ideas, questions and answers. I now know enough to glimpse how much I really do not know about Japanese knives and sharpening. The good side of it is that I have gained a new appreciation to something I already love.
 
Definitely one of the best threads on forum.

Casaluz said:
I was guided to this thread by another member and wanted to thank Dave and everybody else for your ideas, questions and answers. I now know enough to glimpse how much I really do not know about Japanese knives and sharpening. The good side of it is that I have gained a new appreciation to something I already love.
Click to expand...
 
Suddenly crapping my pants at the thought of sharpening my shiny new Watanabe Nakiri.....
 
Don't overthink it. You are rubbing a piece of steel against a rock.
 
If you're happy with the existing configuration there's nothing to worry about, unless you're a EdgePRO victim of course. Freehanding, you start somewhere behind the bevel with the blade very near to the stone, little by little raising the spine, until you've reached the very edge and raised a burr. Verify your progress by looking at the scratch pattern. Only when you got the burr you flip to the other side and repeat the process. As you see, no angles, no proportions. Only restoring a former configuration which has moved a very little bit towards the spine.
 
ThEoRy said:
Don't overthink it. You are rubbing a piece of steel against a rock.
Click to expand...

Benuser said:
If you're happy with the existing configuration there's nothing to worry about, unless you're a EdgePRO victim of course. Freehanding, you start somewhere behind the bevel with the blade very near to the stone, little by little raising the spine, until you've reached the very edge and raised a burr. Verify your progress by looking at the scratch pattern. Only when you got the burr you flip to the other side and repeat the process. As you see, no angles, no proportions. Only restoring a former configuration which has moved a very little bit towards the spine.
Click to expand...

Cheers guys. It's exactly that @ThEoRy, I was simply over thinking. I've always managed to get what I consider a respectable edge, the first post simply got me thinking.
 
Bump:)

I've linked this thread a few times recently and figured it would be cool to bump it just for those who have not had the opportunity to read this--something I find most important to understand how blades are made and how to maintain them.

Thanks for the great thread Dave!

Cheers
 
abit late to this thread, so if the knife is asymmetric then we should be aiming for the right most diagram? (assuming knife is 70/30)

grinds.png
 
Dave Martell said:
Not really.

What you want to do to the edge is follow how the blade is ground. This is accomplished by Refer to Post#1
Click to expand...

Hi Dave, thanks for the quick reply. I read the first post quite a few times and I still don't quite understand. Would you be able to show visually what the below means?

"How can you do this? Simple…you look at the blade and mimic it’s asymmetric grind when working it’s edge bevel. I used to use a straight edge laid on the side of the knife to compare side to side and then follow by rough estimating this form while sharpening the edge bevel. Luckily most of you will have a new knife that you’re starting out on and you’ll likely find that this ratio has already been worked into the bevels and all you have to do is follow along."

Do you mean to hold the knife such that the spine is facing up to the sky and edge resting on the board and then hold something that is a straight edge on each side of the blade? For my knife brand new I notice the bevel on right side is taller than left side about twice as tall perhaps. I was told it is a 60/40 double bevel. Very similar to the right most in the diaghram. Thanks for your help!
 
a bit off topic. But does any one have a spare copy of Dave's sharpening DVD set for sale... trying to grab hold of a copy but unfortunately Dave has discontinued the DVD and I can't find it anywhere

Thanks
 
So, do I get this right? Right handed Knives, I should sharpen left side of the blade ( edge pointing down) with higher angle, and right side with lower angle? Or the opposite?
 
For a righty ground knife it's generally two pennies under the right side, three pennies under the left.
 
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