s grind

[Kevin McGovern]

Are there any good videos on executing an S grind? Barring that, can someone tell me how you do it that works for you?

 

[Metalhead0483]

I admit, I had to look it up... You kitchen knife guys come up with the wildest things sometimes.

 

[timos-]

Well, I will be finishing a big 20cv blade tomorrow actually. 52mm wide by 255mm long K tip blade. It happens to have bevels I ground on one of @Nathan the Machinist 48" radius platens.
So I Leave about .010 thick at the edge before convexing that to zero. The spine is also heavily rounded. So the bevel is concave but then transitions to a convexed edge, so you have this sort of "s" shape idea.

So I just grind the blade on the radius platen , then convex the edge on slack belt...You can play with these variables, but in the end you know its all kind of a pain in the ass and harder to hand finish. I made myself up some curved sanding blocks to help with the finishing

 

[Salem Straub]

As far as discussion of s-grinds, here's a vid that I did a while back showing some differences between flat, mild convex, and s-grinds or differing height when cutting zukes on a board.
[video]

I have some more video on my phone that actually shows the grinding method a bit, I'll upload it and post it here later too.

 

[jdm61]

On a gyuto, do a full height flat grind down to about half thickness at the edge, another flat grind from saying higher than the bottom of the choil to the edge (Think high saber grind where the upper "flat" is not truly flat), convex the edge up about 3/8, cut in your shallow hollow down from the "shindig line" to well above the convex, then thin behind the edge, blend everything together and polish.

 

[tim37a]

Hey jdm,
could you sketch that, please. I'm having trouble visualizing it. Thanks.
Tim

 

[Stromberg Knives]

I'm also interested in the s-grind, if anyone could provide more sketches or pictures on this technique I'd really appreciate it.

 

[kuraki]

I'm also interested in the s-grind, if anyone could provide more sketches or pictures on this technique really I'd appreciate it.

This is greatly exaggerated in dimension otherwise it becomes very hard to see.

 

[jdm61]

Think about the grind on say a KaBar, but with the part from the spine to the top of the fuller not totally flat and make the fuller MUCH shallower. Grind/blend until you cannot see the bottom the fuller, round over the top transition and then convex the edge. The problem that i have with some S grinds is that the 'fuller" is too deep, to the point of being highly visible even in pictures. Same problem that i have with slack belt convex grinds that are way too convex.
This knife has an S grind with a fairly tall convex edge , but you can't really see it.

 

[jdm61]

When I do the grind, I blend away the "hump"at the bottom of the hollow. It goes shallow flat upper bevel, hollow, flat lower bevel then convex edge. All sharp "transitions" are blend away.

This is greatly exaggerated in dimension otherwise it becomes very hard to see.

View attachment 827899

 

[Kevin McGovern]

Is a 12 inch wheel too small to do this on something like a chef's knife?

 

[Stromberg Knives]

Thanks guys! I've read all your great information. But I can't really seem to grasp the preferred order of operation for making s-grinds.

 

[kuraki]

Thanks guys! I've read all your great information. But I can't really seem to grasp the preferred order of operation for making s-grinds.

Well, that's going to vary and everyone's personal preference makes it seem more complicated than it is. Grind a hollow that terminates before the edge. Convex the edge. How wide you leave the edge, how high you make the convex, is all going to vary depending on you, your tooling, and your desired results.

 

[Stromberg Knives]

Haha, thanks for the simpleton version!