Is this a good combat knife?

tim po

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. he asked about 'combat knives', not fighting knives. specific parameters.

I may be misinformed about the 'blood groove' or 'fuller' if that is what it is called. but i will need to read something posted on a site not caller THE BS historian.

The article also did point out something that is very true, most knives for sale to the public today were designed and manufactured for really only one purpose: appeal to the consumer. a knife maker wants to sell knives, not make them. the simpler the knife is usually the better fighting tool.

V-42 knives are legit. and the only missing feature on most of them is a flat pommel, but a thin dagger has extreme penetrating power. but it is not as efficient for slashing. they also do not benefit from a channel, whatever the reason is.
 

Flying Crane

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. he asked about 'combat knives', not fighting knives. specific parameters.

I may be misinformed about the 'blood groove' or 'fuller' if that is what it is called. but i will need to read something posted on a site not caller THE BS historian.

He is not the only source Ive seen to discuss this point. That was simply the first site I found with about 8 seconds of Google-fu. If you want to see it from another source, Im sure you could find one within 15 seconds.
 

Dirty Dog

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I may be misinformed about the 'blood groove' or 'fuller' if that is what it is called. but i will need to read something posted on a site not caller THE BS historian.
There's no "may" about it. You're wrong. It's a common enough misconception, but wrong none-the-less.
V-42 knives are legit. and the only missing feature on most of them is a flat pommel, but a thin dagger has extreme penetrating power. but it is not as efficient for slashing. they also do not benefit from a channel, whatever the reason is.
The fuller makes a blade lighter, stronger and more rigid.
The notion that a thin dagger has some magical penetration property is nonsense.
 

tim po

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i stand corrected, the fuller is just as you say.
i still say that blade shape has everything to do with penetration ability.
 
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Flying Crane

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There's no "may" about it. You're wrong. It's a common enough misconception, but wrong none-the-less.

The fuller makes a blade lighter, stronger and more rigid.
The notion that a thin dagger has some magical penetration property is nonsense.
Im not sure that a fuller actually makes it stronger. It does make it lighter, and if done properly should not weaken the blade, at least not significantly. But Im not sure it actually makes it stronger. Ill need to look into that one.
 

tim po

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you're aggressive, for a worn out tired old fat man. maybe you should be gentle with me. the shape of a blade most definitely affects it's ability to penetrate, i don't know much about magical blades, but maybe you could tell us about them?. or just pick out what i said that was incorrect so you can belittle me and bury all that i said that is true, does that make you feel cooler? i was not responding to you, you don't seem to be here to learn, but to teach. so, respond to the poster, answer his question with your wisdom. we can agree to disagree.

Im not sure that a fuller actually makes it stronger. It does make it lighter, and if done properly should not weaken the blade, at least not significantly. But Im not sure it actually makes it stronger. Ill need to look into that one.
it makes sense, the concavity would increase rigidity, and would help keep a long blade straight. and weight affects balance.

and btw i tried to edit the above comment in favor of the second one, and I regret reacting that way.
 

tim po

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it makes sense, the concavity would increase rigidity, and would help keep a long blade straight. and weight affects balance.

and btw i tried to edit the above comment in favor of the second one, and I regret reacting that way.
and it wasn't directed at you, i was quoting his avatar
 

Flying Crane

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I checked a source on fullers, Jim Hrisouolas, one of his books on blade making. He simply states that it lightens the blade for the width without compromising strength. Nothing about making it stronger. I am not sure that I would buy the notion that it make it stiffer either. If anything, my intuition says it would make it more flexible. I am thinking more on the terms of a sword blade, than a knife.
 

dvcochran

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it makes sense, the concavity would increase rigidity, and would help keep a long blade straight. and weight affects balance.

and btw i tried to edit the above comment in favor of the second one, and I regret reacting that way.
That would depend on how the blade is made. If it is forged to a concave shape then yes, it would increase rigidity (assuming it is tempered).
If it is machined or stamped to a concave shape, then it will have the same rigidness qualities of the metal it was fabricated from. You have to change the molecular properties to affect the modulus of rigidity.

Modulus of rigidity formula: G = /帠 and G = E/(2(1+v)).

It is a tough one to understand.
 

lklawson

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I checked a source on fullers, Jim Hrisouolas, one of his books on blade making. He simply states that it lightens the blade for the width without compromising strength. Nothing about making it stronger. I am not sure that I would buy the notion that it make it stiffer either. If anything, my intuition says it would make it more flexible. I am thinking more on the terms of a sword blade, than a knife.
A fuller makes a blade "stronger" for the same weight and space dimensions, giving it greater rigidity and shear resistance, and works in exactly the same principle that an I-Beam does. It's simple mechanical engineering.

In short, a fuller is the blade equivalent of an I-Beam.

Peace favor your sword,
Kirk
 

lklawson

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That would depend on how the blade is made. If it is forged to a concave shape then yes, it would increase rigidity (assuming it is tempered).
If it is machined or stamped to a concave shape, then it will have the same rigidness qualities of the metal it was fabricated from. You have to change the molecular properties to affect the modulus of rigidity.

Modulus of rigidity formula: G = /帠 and G = E/(2(1+v)).

It is a tough one to understand.
Fullers obey the Beam Equation. The modulus of rigidity is important for the material but you can't apply it in isolation to an I-Beam.

Peace favor your sword,
Kirk
 

Flying Crane

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A fuller makes a blade "stronger" for the same weight and space dimensions, giving it greater rigidity and shear resistance, and works in exactly the same principle that an I-Beam does. It's simple mechanical engineering.

In short, a fuller is the blade equivalent of an I-Beam.

Peace favor your sword,
Kirk
Yes, that is understood. But I think the key portion that often may not be recognized by most people is the qualifier: for the same weight and dimensions. So if you take two blades of identical thickness, shape, taper, and distal taper; in short, two blades that are identical, but with the difference that one blade has a flattened diamond cross-section, and the other has a fuller for some significant portion of the length of the blade, I believe the flattened diamond will be stronger and stiffer. However, the trade-off is that it will be heavier and less maneuverable.

In order to compare two blades of equal mass, one with a fuller and one without, you need to change the dimensions of the blade. If length and base thickness are equal, then the fullered blade will be wider than the non-fullered blade. So no matter how you compare them, there is something about them that is not equal. Either width is different or thickness is different or mass is different. They cannot have equal dimensions (shape) in all respects, if mass is the same, when one has a fuller and the other does not.

Another way to look at it: if you took a square beam with certain width and depth, and you compared it with an I-beam that had the same outer measurements, the square beam is definitely stronger, but also much much heavier. If you took the material from that square beam and turned it into an I-beam of the same length, the width and depth measurements would be much larger, your I-beam would be much larger in those dimensions.

So in making a sword blade (I know, we are moving away from the knife discussion) you can use the same amount of material to make a wider blade (better for cutting) while maintaining good strength and rigidity, and not making it heavier for the extra width.

But if you make a sword blade without a fuller, and then cut a fuller into it and remove some steel and make the blade lighter, you do not increase the strength and stiffness in doing so. What you have done is lighten the blade which makes it more maneuverable, and the resulting cross-section remains structurally sound with good strength and good stiffness. But not more strength and stiffness than it had before the fuller was cut into it.
 

dvcochran

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Fullers obey the Beam Equation. The modulus of rigidity is important for the material but you can't apply it in isolation to an I-Beam.

Peace favor your sword,
Kirk
True, but there no major span to consider in a carry length blade.
 

Dirty Dog

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i stand corrected, the fuller is just as you say.
i still say that blade shape has everything to do with penetration ability.
You can say it all you like, that won't make it true. I've dealt with a couple knife wounds over the last 40 years in the ER, and the shape of the blade really doesn't matter.
Im not sure that a fuller actually makes it stronger. It does make it lighter, and if done properly should not weaken the blade, at least not significantly. But Im not sure it actually makes it stronger. Ill need to look into that one.
The fuller removes material (hence lighter) and increases surface area (hence stronger).
I checked a source on fullers, Jim Hrisouolas, one of his books on blade making. He simply states that it lightens the blade for the width without compromising strength. Nothing about making it stronger. I am not sure that I would buy the notion that it make it stiffer either. If anything, my intuition says it would make it more flexible. I am thinking more on the terms of a sword blade, than a knife.
Jim is a great guy. We disagree on a few things though. Depending on a lot of details about overall blade crossection, materials, forging technique and heat treating the fullered blade may not actually be stronger than the un-fullered (in large part because "strong" isn't really clearly defined). Rigidity might be a better word. But if the two blades have identical characteristics, but the fullered blade uses less material (and is thus lighter) then it's stronger.
That would depend on how the blade is made. If it is forged to a concave shape then yes, it would increase rigidity (assuming it is tempered).
Have you ever seen (or even heard rumor of) someone forging a blade and not heat treating it? I'm honestly not sure how that would even be possible.
If it is machined or stamped to a concave shape, then it will have the same rigidness qualities of the metal it was fabricated from.
Same question. Who stamps knives?
Regardless, the greater surface area of the fullered blade still makes it stronger.
 

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Jim is a great guy. We disagree on a few things though. Depending on a lot of details about overall blade crossection, materials, forging technique and heat treating the fullered blade may not actually be stronger than the un-fullered (in large part because "strong" isn't really clearly defined). Rigidity might be a better word. But if the two blades have identical characteristics, but the fullered blade uses less material (and is thus lighter) then it's stronger.
I disagree with your points. From what Ive read its more about the area of the cross-section. The I-beam shape, when properly loaded. Is stronger than a square beam with the same area of the cross section. But the overall dimensions of that I-beam will be much larger than the square beam. But if we consider the fullered blade as an I-beam and the non fullered blade as the square beam, if the area of the cross section is equal, the shape of the fullered blade becomes significantly wider. Thus to have a meaningful comparison, we need identical area of the cross section. This changes the overall dimensions of the blades significantly.

As I stated, if you make a blade, then cut a fuller into it, you reduce the area of the cross section and it becomes less strong. You have made it lighter, but not stronger and I am doubtful about stiffer. The blade is still strong, I am not implying otherwise. But it does not become stronger by cutting in a fuller.

Good discussion of the i-beam here:
 

dvcochran

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Have you ever seen (or even heard rumor of) someone forging a blade and not heat treating it? I'm honestly not sure how that would even be possible.
Sure it would. Forging is heating a metal to the point it is malleable. Tempering/heat treating is taking it considerably beyond this temperature to change the molecular properties of the metal. Usually done in subsequent heating/cooling stages. This is how properties like hardness are made different.
When you work the hoofs on cattle you want the blade soft so we have made several drawing blades, none of them heat treated.
 

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Sure it would. Forging is heating a metal to the point it is malleable. Tempering/heat treating is taking it considerably beyond this temperature to change the molecular properties of the metal. Usually done in subsequent heating/cooling stages. This is how properties like hardness are made different.
When you work the hoofs on cattle you want the blade soft so we have made several drawing blades, none of them heat treated.
You're not using the terms the same way as a blade maker. And your statement that heat treating is done at a higher temp than forging is just plain wrong.
Depending on the material, forging is done from 900F to 2000F. Most mild steel (probably the most commonly used blade steel) is between 1100F and 1300F.
Tempering and annealing is between 400F and 800F, with that same mild steel example being 400-700F.
Quenching a blade when it's too hot is a good way to start a new blade. After the first one breaks.
It's not really possible to forge a blade without heat treating to at least some extent. Say you heat it hot enough to forge, pound on it, and then set it aside to cool. That's essentially annealing. It's going to be a crappy heat treat, but a heat treat none the less. What you should be doing is forging the blade, then heating and quenching it, and then heating it and allowing it to cool slowly. You can get whatever degree of hardness you like in doing so. Is that worth it for a hoof knife, or just pound it and go with the crap heat treat? Up to you.
 

dvcochran

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You're not using the terms the same way as a blade maker. And your statement that heat treating is done at a higher temp than forging is just plain wrong.
Depending on the material, forging is done from 900F to 2000F. Most mild steel (probably the most commonly used blade steel) is between 1100F and 1300F.
Tempering and annealing is between 400F and 800F, with that same mild steel example being 400-700F.
Quenching a blade when it's too hot is a good way to start a new blade. After the first one breaks.
It's not really possible to forge a blade without heat treating to at least some extent. Say you heat it hot enough to forge, pound on it, and then set it aside to cool. That's essentially annealing. It's going to be a crappy heat treat, but a heat treat none the less. What you should be doing is forging the blade, then heating and quenching it, and then heating it and allowing it to cool slowly. You can get whatever degree of hardness you like in doing so. Is that worth it for a hoof knife, or just pound it and go with the crap heat treat? Up to you.
Had to go back and look. I do have the heat treat temps backwards. Heat treat about 400-800 F. Forging about 1600-2200 F.
This is for 4140 or common tool steel. The number will vary depending on the metal.
I have never seen steel treated at 400 so I have no clue what that would do since 4140 is stable at 325. It would take a Long time.

Have you ever worked an animals hoof? They bleed very easy when trimming or dealing with a callous or ulcer. A soft blade goes a long way.
 

Dirty Dog

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Had to go back and look. I do have the heat treat temps backwards. Heat treat about 400-800 F. Forging about 1600-2200 F.
This is for 4140 or common tool steel. The number will vary depending on the metal.
I have never seen steel treated at 400 so I have no clue what that would do since 4140 is stable at 325. It would take a Long time.
It is. I do mine by sticking them in an old oven. A couple hours at heat, then cool slowly. I generally leave them in overnight.
Another fellow I know swears by heating them with a torch and then burying them in sand. We all have our preferences. Like, I prefer canola oil to water for quenching. I don't think it actually changes the heat treat significantly, but it makes the shop (one bay of our garage...) smell like someone baked cookies.
Have you ever worked an animals hoof? They bleed very easy when trimming or dealing with a callous or ulcer. A soft blade goes a long way.
I have not. What is the advantage of a soft blade?
 

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It is. I do mine by sticking them in an old oven. A couple hours at heat, then cool slowly. I generally leave them in overnight.
Another fellow I know swears by heating them with a torch and then burying them in sand. We all have our preferences. Like, I prefer canola oil to water for quenching. I don't think it actually changes the heat treat significantly, but it makes the shop (one bay of our garage...) smell like someone baked cookies.
I haven't heard of anyone that quenches with water. Hardens the blade too much and induces stress. I'm not sure even a decent tempering could take it out. Is there something that I'm missing? Some sort of steel that likes to be water quenched?

Peace favor your sword (mobile)
 
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