What is the toughest type of knife grind?

Are you talking about the toughness of the edge, or the general robustness of the knife?

Theoretically, a convex has the best edge strength and is also a very robust blade overall. A scandi has the least edge strength, but is a very strong blade overall, since much of it is full spine width.

Honestly, I doubt that you'll notice much of a toughness difference between convex and saber. IMHO, I would just pick the grind that performs best for you.
 
You don't see full convex grinds anymore. But that would be the toughest. Sabre, then flat then hollow. There are hybrids of all of these.
 
This, but it doesn't cut very well.
24696d1280095470-ot-civil-war-exploding-cannonball-img_3032.jpg


In all seriousness, for a given edge angle and stock thickness you can't get thicker than a zero saber grind. Or at least not without resorting to a highly improbably hollow grind of extreme thickness and zero functional application. Convexes actually are a thinner geometry than flats when edge angle and stock thickness are held constant. They start at that fixed edge angle and then the angle continuously reduces until it's parallel.
 
ThunderJellyFishhh said:
Can anyone tell me what is the toughest type of knife grind?

Is it saber or convex? or any other type of grind?
Click to expand...

Welcome.

For two blades made of the same steel, the thicker one will be tougher.

For blades with the same edge angle, a flat grind is thicker behind the edge than convex.

tangent2_zpskzpnsnza.gif


The angle where two curves meets it the angle formed by the tangents to those two curves at the point where they meet. In the graph above, the red lines show those tangents formed by the two curves forming the convexed edge.

With a flat ground edge the edge IS the tangents...i.e., the red lines. Clearly the blue is inside the red, and the red is thicker behind the edne, and, hence, more durable.

Now, the adherents of a noted convexed edge knife maker will chime in and claim the edges he makes somehow defy mathematics, geometry, and physics.

Thicker is more durable, and for a given edge angle, a flat ground edge is thicker behind the edge than a convex. (Actually "hollow" is the thickest.)
 
I would say full convex or typically called an axe grind. Problem with this grind on knives, it is too thick for efficient cutting unless the stock being used is thin. Works great for an axe but with knives it has to be a flatter convex grind. I've experimented with the convex grind for 12 years and have found you need to flatten the profile of a convex to make it a better cutter. Even so it is stronger because on more material behind the edge and up to the spine. With any grind, steel type and the heat treatment rules with strength. Cutting ability, the geometry of grind and edge are most important.
Scott
 
FortyTwoBlades said:
In all seriousness, for a given edge angle and stock thickness you can't get thicker than a zero saber grind. Or at least not without resorting to a highly improbably hollow grind of extreme thickness and zero functional application. Convexes actually are a thinner geometry than flats when edge angle and stock thickness are held constant. They start at that fixed edge angle and then the angle continuously reduces until it's parallel.
Click to expand...

As usual, nailed it. :thumbup:

grinds_zpsactzzxpo.png
 
He didn't ask for edge grind, he asked about knife grind. So the correct assumption is knife profile. Zero edge is an edge profile.
 
Cobalt said:
He didn't ask for edge grind, he asked about knife grind. So the correct assumption is knife profile. Zero edge is an edge profile.
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Zero means that the only bevel IS the edge bevel. The primary grind and the edge are one and the same. One could even describe it as a primary grind that is brought fully to an apex.
 
Thicker is tougher, therefore we can eliminate relief bevels from the equation entirely, and that leaves us with looking at the three possible forms of edge bevel, out of which hollow is the thickest, but also impractical because it won't cut for beans in that kind of thickness range, meaning that you're left with flat and convex, out of which flat is the thicker geometry.
 
In the early 2000's, Bill Moran commented that a lot of the convex grains that he was seeing were way too convex. A lot of people may not realize this but Bill did his convex grinds and of like the Japanese sword makers did. He did not use a slack belt, but found a series of "facets" into the blade and then blended. If you look at a Moran or a Robbin Hudson convex grind, they are very "shallow." I have seen slack belt convex grinds done where the spine is thinner than the blade like 1/4 blow the spine. Scott, you may have mentioned this before, but I have fond that a "rotary platen" is a really good tool to have if you want to mess around with convexing, be it the entire blade or just the edge area.
Gossman Knives said:
I would say full convex or typically called an axe grind. Problem with this grind on knives, it is too thick for efficient cutting unless the stock being used is thin. Works great for an axe but with knives it has to be a flatter convex grind. I've experimented with the convex grind for 12 years and have found you need to flatten the profile of a convex to make it a better cutter. Even so it is stronger because on more material behind the edge and up to the spine. With any grind, steel type and the heat treatment rules with strength. Cutting ability, the geometry of grind and edge are most important.
Scott
Click to expand...
 
As for what is the toughest grind, I will go with the parallel full flat grind. :p
 
jdm61 said:
In the early 2000's, Bill Moran commented that a lot of the convex grains that he was seeing were way too convex. A lot of people may not realize this but Bill did his convex grinds and of like the Japanese sword makers did. He did not use a slack belt, but found a series of "facets" into the blade and then blended. If you look at a Moran or a Robbin Hudson convex grind, they are very "shallow." I have seen slack belt convex grinds done where the spine is thinner than the blade like 1/4 blow the spine. Scott, you may have mentioned this before, but I have fond that a "rotary platen" is a really good tool to have if you want to mess around with convexing, be it the entire blade or just the edge area.
Click to expand...

You are right about the slack belt and yes I use the rotary platen exclusively when blending a convex from flat. Flat grind first then finish to convex on the rotary platen. The rotary platen depending on the tightness of the belt will better control the geometry of the convex grind. With a slack belt yes, you can see the spine thinner depending on the angle in which you make the passes across the belt. All my finished edges are done on the rotary platen.
Scott
 
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With a convex grind, it all depends on the radius at the point of intersection. A larger radius has more cutting power and a smaller radius has more strength. Both have less friction than any grind that has an edge grind that is more obtuse than the blade grind.
 
marcinek said:
Welcome.

For two blades made of the same steel, the thicker one will be tougher.

For blades with the same edge angle, a flat grind is thicker behind the edge than convex.

tangent2_zpskzpnsnza.gif


The angle where two curves meets it the angle formed by the tangents to those two curves at the point where they meet. In the graph above, the red lines show those tangents formed by the two curves forming the convexed edge.

With a flat ground edge the edge IS the tangents...i.e., the red lines. Clearly the blue is inside the red, and the red is thicker behind the edne, and, hence, more durable.

Now, the adherents of a noted convexed edge knife maker will chime in and claim the edges he makes somehow defy mathematics, geometry, and physics.

Thicker is more durable, and for a given edge angle, a flat ground edge is thicker behind the edge than a convex. (Actually "hollow" is the thickest.)
Click to expand...

The flat edge you've shown has at least a 100 deg included angle. Great for chopping nails in half, but useless for cutting anything.
 
hermit dave said:
The flat edge you've shown has at least a 100 deg included angle. Great for chopping nails in half, but useless for cutting anything.
Click to expand...

It's an exaggerated image to make the difference more visible. The convex also has the same thick angle, but that angle then reduces the farther back from the edge you get.
 
hermit dave said:
The flat edge you've shown has at least a 100 deg included angle. Great for chopping nails in half, but useless for cutting anything.
Click to expand...

And also, a convex edge isn't blue! You got me! :rolleyes: Its an illustration. You could make the angle more acute if you want, and the convex will still be inside the flat.

Or you can ignore it and base arguments on handwaving. I'll stick with mathematics and geometry.
 
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