Best knife grinds over the long run?

I'm not sure if this is best in here or in the sharpening area, as it is sharpening related, but it feels more appropriate here.

I've been wondering for a while about how various types of knife grind hold up over time. I'm not sure how best to explain what I mean and the last sentence really doesn't help...

As you sharpen a knife over many years, you lose blade height. As you go you'll thin behind the edge to account for the increasing thickness of the blade. Assuming that over many years you lose a significant proportion of the initial height, which grind (concave, convex, "S", etc) will serve you best at that point? I'm thinking that one particular grind which is amazing new would tend to cause problems later on.

I'd like to hear from anyone who's used a blade that's lost a lot of height. Am I missing the point here, at that point would the blade need to be reground or have been thinned to such an extent that the initial grind is a irrelevant?

I tended to keep knives I liked a lot at work. They would lose height over the years. For me would sharpen heel to tip first at a low angle close to the stone(Thinning bevel) Then raise the angle for final bevel. It is important to sharpen all of the knife edge wt. good technique so no high heels or bird beak tips.

The two blended bevels form a convex edge that glide through food. If your sharpening is good, you can wear away over .5" & still have correct geometry. As the blade gets thicker it may take more aggressive thinning behind the edge, however you can use a Japanese Gyuto over the years with just thinning behind the edge a little because the quality blades often are thinner a ways up the face making sharpening easier than a thick knife.

Both Dave & Jon explain why sharpening at a high angle without thinning as the blade gets thicker the angle gets wider does not cut as well & dulls quickly.

Hollows in the blade face reduce the amount you need to remove when thinning, otherwise the geometry is mostly impacted by what you've done to reduce the height by that much. If you've maintained geometry behind the edge by thinning it will cut similarly, that's part of the purpose of thinning.

If it's that high up to where it's getting into the blade face grinding or affecting knuckle clearance I'd just get a new knife.

I've wondered about this too. As MAS4T0 said, with repeated sharpening and thinning the blade height is reduced. And with an 'S' grind like say in a Takeda, surely this would complicate how one should "correct" and try to maintain the original geometry. I can't imagine how this could be done with stones myself. I'm just glad my knives aren't nearly at any stage of wear to be concerned yet.

At a certain point, I think its best just to stop worrying about maintaining the factory grind and just thin the bevels and blend them to your own liking. After losing 4 or 5mm of blade height, so much steel has been lost that the performance really becomes a reflection of your own abilities and little to do with the makers.

^^^ what he said

im just paraphrasing tk,:biggrin: but its true IMO.

labor of love said:

At a certain point, I think its best just to stop worrying about maintaining the factory grind and just thin the bevels and blend them to your own liking. After losing 4 or 5mm of blade height, so much steel has been lost that the performance really becomes a reflection of your own abilities and little to do with the makers.

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Right, that's one of the reasons to learn freehand & sharpen your own knives. The knife gets trained to your own style of sharpening. This makes them easy for quick touch ups to refresh the edge.

MAS4T0 said:

at that point would the blade need to be reground or have been thinned to such an extent that the initial grind is a irrelevant?

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This sounds like a great time to buy a new knife...
By the time you've lost that much height surely your knuckle clearance is crap now anyway

i personally love making a knife my own, little by little over the years.

Sure, all the above comments are true and it's what I'd do as well. However, just out of compulsive curiousity, is there any way to maintain the geometry of an 'S' grind if one was just using stones?

Sambal said:

Sure, all the above comments are true and it's what I'd do as well. However, just out of compulsive curiousity, is there any way to maintain the geometry of an 'S' grind if one was just using stones?

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I seriously doubt it.

Geo87 said:

This sounds like a great time to buy a new knife...
By the time you've lost that much height surely your knuckle clearance is crap now anyway

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Howzit Geoff you never had knife you could not retire cuz it cut so well? Had a 240 thin carbon gyuto that got so worn turned it into a slicer like a suji. Maybe it is my thrifty Scottish side:whistling:

By the way teaching your method of splash & go for touchups at work. Cherry Co. here sells King & Shapton Pro at a good discount to students.

If the only criteria is longevity, not food release, than a thin, flat ground, San Mai blade would be the easiest to maintain until its a toothpick, but as has been stated above, you're better off replacing it and using it to open boxes/cans etc.

A gyuto with the geometry of a nakiri is the easiest to maintain over time. The height will change but nothing else, if you sharpen it correctly.

I also have a plan for an amazing new geometry that runs into problems later in life, so don't steal it

Squilliam said:

A gyuto with the geometry of a nakiri is the easiest to maintain over time.

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I was under impression that "nakiri" is a profile and not geometry. Meaning that Nakiri can be made with more or less any geometry, be convex, hollow or it S-grind.

I agree with the sharpening and making it your own. my masamoto ks is now my favourite knife and the more I use it the better it gets.

Squilliam said:

A gyuto with the geometry of a nakiri is the easiest to maintain over time.

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I dont think there is a single "geometry of a nakiri". Unless youre making a general statement about knives with thinner grinds?

I would say traditional double bevel knives with wide, flat-ish, bevels are easiest to maintain and learn on as you sharpen the whole bevel every time you sharpen the knife, thus always maintaining thin geometry. This goes for Takeda's as well as the hollow is of no concern to sharpening, you thin and sharpen the bevels as you use the knife.

icanhaschzbrgr said:

I was under impression that "nakiri" is a profile and not geometry. Meaning that Nakiri can be made with more or less any geometry, be convex, hollow or it S-grind.

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Oops yea, I was picturing something like this in my mind



Flat and parallel on the kuro, then flat bevels on the iron until a hamaguriba edge.