Asymmetric grind?

[madmotts]

Wondering if there was anything different about sharpening double bevel asymmetric grinds. I was on a zoom with a buddy talking him through basic sharpening and he showed me a Mac Superior santoku. It looks like a typical double bevel but he described on side as being flat and the other being (right) ever so slightly rounded and angled. Sure enough he sent me this image(below). I put the other image to show the back side is indeed beveled.

With my limited knowledge of single bevels, the basic idea is zero on the beveled side and flat on the back side. I don’t think that applies here

 

[Kippington]

Have you taken a look at this thread? I think it should answer your questions.

https://www.kitchenknifeforums.com/threads/a-basic-explanation-of-asymmetry.33951/

 

[madmotts]

Hmm. After reading this, the idea sound simple, but what if that left side (flattish side) bevel hasn't been established? It's not the same angle as the other side right?

 

[Benuser]

What I do, is creating a convex bevel on the right side that follows the face. It will end at an angle of 10-12°.
On the left side, I make a straight bevel at a much higher angle, to balance the friction on both sides and reduce steering. How much steering is acceptable is a highly personal question. Please be aware the edge is off-centered to the left. The left bevel will be very narrow. Common values for the angle are 15-20°.
Here a photo of a very thick blade — a yo-deba — showing the right bevel — left on the picture — as the extension of the blade's face.

 

[mikemac]

The EASY answer...for BASIC sharpening...use the magic marker trick to follow the edge angles and grind established by the manufacturer (MAC)
I seem to recall a detailed thread from years ago led by DaveM and the end result was 'don't mess with the grind the manufacturer puts on the knife' (unless you really know what you're doing. So...IMHO...Magic Marker = KISS

 

[Delat]

Here’s another example, with this one you can see the core steel so it helps to understand the long-term implications. Out of the box the bevel appears to be 50/50 and I’m just maintaining it there for now. At the first “real” sharpening I’ll start adopting angles like @Benuser showed above (roughly70/30), shorter and steeper on the “flat” side, longer and shallower on the convex side.

Over a long period of time the bevel on the convex side will become pretty large and the edge will be more clearly offset to the flat side. If you kept a straight 50/50 you can see that eventually the edge would drift away from the the core steel.

TBH at my rate of use though, this is more academic than practical. I doubt in my lifetime that I’d take more than a mm or two off the edge (barring chips that need to ground out).

 

[madmotts]

Great stuff folks. keeping in mind all that’s been that’s mentioned, I’ll start w the sharpie and see where that takes me. The general idea is to go steeper on the flat side and flatter on the convex side. Based on the pict (condition of the knife) I won’t be shaving off very much metal.

I probably won’t see this knife in person for a bit (social distancing) so it’ll give me sometime to mull this over.