Argument against flat grinds

shane45-1911 said:
There is nothing wrong with convex grinds for certain uses. Yes, they typically hold an edge well when used for harder tasks. BUT.....

I do not agree with Mike saying they are "better" than a full flat grind. That is ridiculous. It depends what you are cutting. If you are doing general knife cutting stuff, or food prep, or heck - just whittling, you aren't going to find a better grind than FF (or arguably hollow ground). To say otherwise just shows either ignorance, or the total lack of desire to offer blades with more than one grind option.

I want my axe to be convex - but I have never in 50 years of owning a knife said "Jeez, this would cut a lot better if it was convex." Never. NEVER.
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You often get these kind of comments from people who only know about convex grinds in relation to axes. You can't compare an axe grind to a Bark River convex grind, they are two entirely different things. The Bark River grind has a much sharper angle and cuts like a scalpel.
 
Mike in the OP video is talking about a zero full flat grind, where there is no edge bevel. Almost every full flat grind has an edge bevel, and that bevel can be thick (.03 inches) or thin (.003 inches) at the edge shoulders (BTE). And it can be acute (10 degrees inclusive) or more obtuse (30 degrees per side).

It is those characteristics that determine how well an edge can hold carbides.

Mike is just selling knives in this video, and he is omitting key information about the actual geometry.

The truth is that a convex grind can be virtually identical to a V edge.

Or, a convex edge can be more obtuse or more acute than a V edge.
 
Twindog said:
Mike in the OP video is talking about a zero full flat grind, where there is no edge bevel. Almost every full flat grind has an edge bevel, and that bevel can be thick (.03 inches) or thin (.003 inches) at the edge shoulders (BTE). And it can be acute (10 degrees inclusive) or more obtuse (30 degrees per side).
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Thats not how I took the video, what I wrote below is how I understood what he said.


Cobalt said:
I have only owned two bark rivers and I don't have them anymore, so I can't check them out. However, lets say you take a 1/4" thick, 2 inch wide blade and give it a full flat grind, then convex the edge. The only way to make that blade a full convex is to grind away a large amount of material from the edge. A flat ground blade is not as thick in any part of it's cross section as a convex blade. So that same blade might lose half an inch or more of it's width and it will lose the original edge. New edge would need to be put on it. Not sure why anyone would do that. But I am not a knife maker so....I guess I am missing something here.
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I also took the OPs video post to be talking about a FF zero ground blade vs. a convex. In which case what Mike says has validity. A convex is much stronger and will out last a zero ground blade. Each has their place and use but if that one factor is all to be considered in an overall use cutting any and everything the convex edge will last longer than a zero grind with no micro bevel.

That said a full flat blade with a micro bevel is an entirely different thing than a full flat zero grind blade. And most full flat grind knives have micro bevels.
 
Dr Heelhook said:
You often get these kind of comments from people who only know about convex grinds in relation to axes. You can't compare an axe grind to a Bark River convex grind, they are two entirely different things. The Bark River grind has a much sharper angle and cuts like a scalpel.
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Again, as I stated earlier.....never in 50 years of owning and using knives had I ever wished for a convex grind. NO convex grind ever cuts like a scalpel, or scalpels would have convex grinds.

Wait for it.........

Scalpels are FLAT GROUND.
 
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shane45-1911 said:
Again, as I stated earlier.....never in 50 years of owning and using knives had I ever wished for a convex grind. NO convex grind ever cuts like a scalpel, or scalpels would have convex grinds.

Wait for it.........

Scalpels are FLAT GROUND.
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Well, a whole lot better than an axe anyway :). BTW, not that I'm trying to force you or anything, but have you ever held or used a Bark River knife?
 
I have a Sunfish Forge with a flat grind & a convex edge. It's O1 at 61Rc and it holds an edge better than a flat grind. Not sure if its the grind, the steel, the edge or all 3. The maker, Don Hanson, said it was all 3 :) The knife was made for a truck driver to cut belts, hoses, tires...It works great.

Most people don't like a convex grind because they don't know how to sharpen it and maintain the edge. I do as Don told me 400-600 grti sandpaper on leather or cardboard. I've had it for many years and never put it on a stone.
 
The main argument of the video is that convex edges are stronger and last longer than flat ground edges because there is more material to support the carbides. At around 2:05 he admits that FG edges can be sharp, they just don’t last.

Arguing for or against this premise is not something I can do from experience so I won’t try, but I will say it”s a mistake to treat all convex edges the same. Some will be more or less acute than others, which will affect the strength argument. I can imagine cases where very acute CG would provide less support to carbides than a less acute FG bevel. Also, different steels form carbides at a different rate and size. A very fine grain steel may have carbides small enough where the FG bevel provides all the support necessary, making the extra material of the CG unnecessary. So, there’s a lot of important info left out of his argument IMO. In some cases he may be right, but in others I have my doubts.
 
JJ_Colt45 said:
That said a full flat blade with a micro bevel is an entirely different thing than a full flat zero grind blade. And most full flat grind knives have micro bevels
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This use of language in knife world shits me, a FFG can NOT have a microbevel.

When anyone says a FFG with a microbevel is equivalent to saying a square circle.

If it has a bevel it not FF.

I own one of the few FFG knives I have ever seen, it is about a half inch thick BTE and has a zero degree edge. There is one angle, one grind from spine to edge.

Nearly everyone here including makers who claim they have FFG don't, at best they have a high Saber grind with a microbevel and some kind of secondary grind.
 
Houlahound said:
This use of language in knife world shits me, a FFG can NOT have a microbevel.

When anyone says a FFG with a microbevel is equivalent to saying a square circle.

If it has a bevel it not FF.

I own one of the few FFG knives I have ever seen, it is about a half inch thick BTE and has a zero degree edge. There is one angle, one grind from spine to edge.

Nearly everyone here including makers who claim they have FFG don't, at best they have a high Saber grind with a microbevel and some kind of secondary grind.
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FFG means it goes from the spine to the primary bevel.
 
AG Russell has a good page with pics, showing knife grind types.

Yes, a full flat grind typically has a secondary grind, and the pic illustrates it rather well....

agrussell.com

Blade Grinds

The grind on a blade lends itself towards different advantages and disadvantages. Some are stronger, others are sharper, and some try to find a balance of both. Grinds: Flat, Hollow, Sabre, Chisel, Convex, American Tanto Dual, and Scandi.
agrussell.com agrussell.com

Quote from AG Russell:
"In my opinion, the convex grind is useful only in large chopping blades and axe formats. I do not think the convex grind is useful in smaller knife formats."

I agree 110%.
 
Houlahound said:
This use of language in knife world shits me, a FFG can NOT have a microbevel.

When anyone says a FFG with a microbevel is equivalent to saying a square circle.

If it has a bevel it not FF.

I own one of the few FFG knives I have ever seen, it is about a half inch thick BTE and has a zero degree edge. There is one angle, one grind from spine to edge.

Nearly everyone here including makers who claim they have FFG don't, at best they have a high Saber grind with a microbevel and some kind of secondary grind.
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You are confusing the type of grind with the type of edge and mashing them together...you need to separate the concepts. To clarify what the Duck stated... when referring to the grind full, 3/4 or high, saber or low all refer to the height that the grind is taken in relation to the spine.
 
The duck is right. A zero flat grind (no secondary bevel) is rare, but a FFG is common. Makers describe that as a flat grind that extends right up to the spine. It is forgiving to grind since you don't have to worry about keeping a straight crisp transition to the flat. The angle for a zero ground FFG is too small to be robust, so a second bevel is used. This makes it much easier to sharpen.

I have made some very sharp convex grinds and have a large chopper I'm very happy with, but overall for small knives I prefer flat with a small secondary bevel.
 
The Aflac Duck said:
We here at Bladeforums know what FFG means (well, most of us). Feel free to use the term how you see fit.
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Yeah the AG Russel chart gets posted here a lot like it's the official BF definition.

Here is blade HQ chart with better graphics better explanations than Russel.

Certainly no universal agreement on what FFG is. I will stick with the conventions of the English language and logic where full means full.

https://www.bladehq.com/cat--Knife-Grinds-Guide--3580
 
Houlahound said:
Yeah the AG Russel chart gets posted here a lot like it's the official BF definition.

Here is blade HQ chart with better graphics better explanations than Russel.

Certainly no universal agreement on what FFG is. I will stick with the conventions of the English language and logic where full means full.

https://www.bladehq.com/cat--Knife-Grinds-Guide--3580
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Ha ha, those are just cartoons, look at the convex!
 
This is objectively incorrect, i created a thread with pics of a zero angle flat grind tradesmen knife that is virtually indestructible.
"
The angle for a zero ground FFG is too small to be robust, so a second bevel is used."
 
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