Overgrind?

[Bart.s]

Hi all!

My first decent gyuto was a Misono 440. It's the knife I learned how to sharpen on and I still practice on it. I have tried to keep the original edge geometry at 30/70, the 30 edge bevel is still quite small and the 70 edge bevel is about twice as big.

Only, there is a spot on the heel of the 70 side that remains small. See the pictures:

Whatever I try, I can't get it out. Is this what they call an overgrind/hole in the grind? And is there something I can do about it? Thanks!

 

[friz]

From the pictures looks like the knife profile isn't right, the heel is higher than the part of the blade you highlighted.
Can you shoot a picture of the knife on the chopping board, as you would cut.

 

[Bart.s]

Tried to capture it best as I could:

The knife doesn't really seem to have a flatspot, more like a slight, gradual curve.

 

[friz]

That might affect the sharpening.
Also, stone is flat?

 

[Bart.s]

I sharpen the knife on the NP400-NP800 and do light deburring strokes on the NP3000. Stones get lapped with an Atoma 140 regularly.

 

[Benuser]

Tried to capture it best as I could:
View attachment 126917
The knife doesn't really seem to have a flatspot, more like a slight, gradual curve.

That curve is common with the Misonos. Also common: quite an abrupt thickening at the heel, and a very, very slight upswing. OOTB the widest point is at a few millimetres from there. Do you have a micrometer?

 

[Bart.s]

That curve is common with the Misonos. Also common: quite an abrupt thickening at the heel, and a very, very slight upswing. OOTB the widest point is at a few millimetres from

Unfortunally, no. But if the heel has an abrupt thickening, wouldn't the edge bevel flair out only at the heel? The edge bevel is quite even on the whole blade, except for that spot before the heel. The bevel at the very end of the heel is just as thick as the rest of the bevel.

 

[ian]

The profile is not a problem, as @Benuser said. The bevel width does indicate to me that there’s a bit of irregularity in the grind, i.e. the knife is thinner in the area you highlighted. But it’s fine. You’re obviously still contacting the edge when you sharpen, so probably the only issue is the aesthetics of the bevel. Relax and learn to love the overgrind. You’re not going to put a kasumi stone finish on it, so who cares if there are low spots. And don’t stress about a perfect 70/30 or whatever either. If your knife doesn’t steer to one side when you go through hard produce, you’re doing fine.

 

[Bart.s]

The profile is not a problem, as @Benuser said. The bevel width does indicate to me that there’s a bit of irregularity in the grind, i.e. the knife is thinner in the area you highlighted. But it’s fine. You’re obviously still contacting the edge when you sharpen, so probably the only issue is the aesthetics of the bevel. Relax and learn to love the overgrind. You’re not going to put a kasumi stone finish on it, so who cares if there are low spots. And don’t stress about a perfect 70/30 or whatever either. If your knife doesn’t steer to one side when you go through hard produce, you’re doing fine.

It doesn't really bother me (haha well, perhaps a little, but that's my OCD/perfectionist ), but like I said, it's now a practice knife/beater/lent to friends knife.

But if it happens on knives which I care some more about, anything there can be done about? Or would it require thinning the whole blade to the same thickness?

 

[RDalman]

Imo this is not a overgrind at all. I consider a overgrind to be when the knife is ground through the centerline and there is no steel left to have a distally straight apex on. Just wanted to add that to @ian s good answer

 

[ian]

But if it happens on knives which I care some more about, anything there can be done about? Or would it require thinning the whole blade to the same thickness?

Yea, if you don’t like how the uneven bevel looks, thin the knife near the edge on a stone, refinish it with sandpaper or something (might lose/lighten the logo when you do that), and then cut in a new edge bevel. Or just try to visualize the bevel as a smily face that projects love at you all day long.