What is a blood groove for

Here is what I came across at A.G. Russell's Knife Encyclopedia.

Blood Groove
"I hate to tell you this, because this term really sells knives, there is no such thing as a blood groove and there is no sucking action that will hang up a knife in a victims body. The term is "Fuller"; this is a groove that lightens and stiffens."

Taken from A.G. Russell's Knife Encyclopedia http://www.agrussell.com/faq/index.html
A great site
 
Hmm, since a lot of people don't seem to be reading the FAQ, I'll summarize:

The fuller does lighten and stiffen the blade -- on a very long knife, like a sword. On anything shorter, the amount of metal removed usually does not make any noticeable difference, so it can be considered decoration.

Summary:

On swords: lighten and stiffen
On knives: decoration

Joe
 
This is a standard question here and over at SFMO. A "blood groove" is, as others have said, a way to lighten a blade while retaining strength. While this is not so important in a knife, think about a sword blade that is 36+" long. It makes a difference. And, yes, it is really called a "fuller". I am thinking of suing for copyright infringement (*wink*).
 
It's been a long time since I've looked at the FAQ -- I thought it explained about twisting forces. If it doesn't it should be updated, IMHO, even though that's primarily a concern for swords; if we're going to have a FAQ about fullers it ought to explain what they're really for correctly. There are guys at www.netsword.com who know a lot more about swords than I do, but I think I can explain this adequately....

First, if you make something twice as wide it becomes twice as resistant to lateral bending -- but if you make it twice as thick instead it becomes much more than twice as stiff. If that isn't old news to you, experiment with available materials and see for yourself. Now, given that ...

Imagine you are a swordmaker. Your customers want swords that are light and fast, but if your swords get a reputation for breaking or bending in use you won't have any customers. You can forge a sword with any cross-section you want, as thick or as thin as you want -- how can you make a light sword that won't bend or break? (To simplify, let's just talk about double-edged swords; you can easily apply the same principles to single-edged swords.)

First, forge a simple diamond cross-section blade. That has great resistance to bending forces because it has a very thick ridge down the middle. But it has little resistance to twisting forces, because when something twists the parts near the center don't get moved much -- it's the parts well away from the center that have to resist twisting forces, and your diamond cross-section blade has its strong thick part right at the center.

So, you take a tool that looks like a chisel with a rounded-off edge and you set the blade on a matching tool stuck in a hole in your anvil, and you forge a fuller right down the middle of each side of the blade.

Now, you haven't lightened that blade a bit, and you haven't stiffened it against bending forces at all, either; in fact you've made it less resistant to bending, because it now resists bending with two ridges that aren't as thick as the original single ridge -- in effect the same as a wider but thinner ridge. But those two ridges are away from the center where they can resist twisting forces, and your blade is now much more resistant to twisting.

That's what a fuller is for.

-Cougar Allen :{)


[This message has been edited by Cougar Allen (edited 07 December 1999).]
 
I had a very interesting conversation with a Chinese speaking friend of mine today. He is fond of translating Ancient Chinese texts into English and knows a great deal about the martial arts and philosophy of all sorts. When I mentioned the 'blood groove' concept to him he said, "yeah, so?"

Apparently, the idea of a 'blood groove' in a sword goes back much farther into history than I claimed previously in this thread. It is not Japanese in origin, but rather, Chinese (given my understanding of Japanese anthropology, this claim makes some sense). My friend says that the literal translation of ancient Chinese texts going back centuries (maybe even millennia) for the fuller in a sword is transcribed as 'blood groove'. So the idea of calling a fuller a 'blood groove' predates modern marketing by many centuries if not more. He also reiterated the idea of the 'blood groove' being necessary to reduce suction and lessen the force of removing the sword from an opponent bodies. In addition, he talked about the need to allow a channel for blood to flow from the opponent in order to stop him quickly from continuing combat (like the concept of Not removing a penetrating weapon unless you want to bleed to death quickly). He said that if the sword Only penetrated the body of one's opponent, it probably would not stop him from continuing his attack. The idea behind the blood groove was to quickly disable one's adversary, to force him to collapse, and stop attacking.

I was very confused by all of this, since I am quite sure that the physics of bodily penetration does not support the usual concepts behind the 'blood groove' or fuller. I tried to counter his reasoning by explaining that the fuller will increase torsional resistance in a longer blade, and make the blade lighter and therefore faster in combat as well as more resistant to twisting forces. He responded that I was "thinking with my modern mind". As we continued discussing this issue, I raised the possibility that an ancient Chinese swordsmith had realized the engineering ideas behind the hollowed out fuller in a long blade and that over time, this channel simply became known as a 'blood groove' because this is where blood will remain on the sword after use.

My friend was adamant that this Was Not at all Important. Whether or not the idea of forging a fuller resulted from a flash of understanding of physics (lighter, faster, and stronger) or from the concept of the 'blood groove' (your opponent stops fighting sooner) did not Matter at all. He seemed to think it likely that the ancient Chinese sword smith who first forged a fuller was Not thinking about making a lighter, faster, or more torsionally resistant sword, but only trying to make a More Effective Weapon.

So perhaps the invention of the fuller was a complete accident from the viewpoint of the physics involved. A fullered sword is going to be faster and more effective than a sword without the fuller in a real fight. Why or how it came to be is not important. The channel in such a blade has been called a 'blood groove' for centuries by the Chinese. So my claim that this term was merely marketing hype invented in this century IS WRONG.

However, the use of a blood groove on a short blade still serves no functional purpose, and is primarily decorative. Perhaps the marketing guys at Marbles Corp. knew some of this history, or perhaps human intuition (right or wrong) is a more powerful force in human history than mere logic alone. Anyway, I wanted to relay this 'new' information to all of you reading this thread. The Fuller in a sword serves a function that can be explained by physical and engineering principles to the modern mind, and entirely different reasons to the intuitive and ancient mind. It makes no difference. The blood groove Works in a long sword. In a shorter blade, it still serves no real functional purpose and becomes merely a decorative feature of the blade.

As a scientist, I am interested in testing the hypothesis that the 'blood groove' will disable an opponent more quickly, but there is a shortage of volunteers for this experiment and I do not support involuntary experiments of this sort in either humans or animals. So I conclude that the 'fuller' has sound physical reasoning for its utility, and that the 'blood groove' concept may have been the driving force behind its discovery. Some of the greatest inventions occurred because of accident and faulty reasoning. It makes no difference. The fuller is a blood groove. And a blood groove is a fuller. Same difference. Capiche?

Paracelsus
(we scientists are always ready to change our minds in light of new evidence)
 
You might ask him what his source is. Because I'm not entirely convinced.

If a fuller is indeed a blood groove, it would follow that it should be common on thrusting weapons and be non-existant on purely slashing weapons.

I have seen a few Chinese "jians", which were very similiar to Western "cut and thrust" swords, and served the same function as an early rapier. It was used primarily to thrust. None of the examples I've seen have a fuller. I have also never seen any historical illustrations of a jian with fullers. Granted, there maybe some I don't know about.

Then there is the Chinese "dao", which is very much like a European falchion. Curved blade, with a much wider blade at the cutting area than the riccasso. This is a pure cutting weapon. There is always a fuller on the dao. And the fuller never even reach the point. So even if you used it to thrust, the blood groove feature would be of no use to you.

On European swords, a similiar trend exists. Viking swords, which had rounded tips not made of thrusting, all have a wide fuller that streaches to the point. Whereas thrusting swords of the Middle Ages rarely had them. When they did, the fuller usually stopped well short of the tip.

 
I just had a thought that possibly the reason for the blood groove or fuller on modern knives could be to save on materials. If you could save just 1/100 of a pound per 16 oz. blade by putting a blood groove in it after 100 blades you would have saved enough material to produce another blade.
 
The ancients did all sorts of things to save on material. But steel is cheap now. A blade is worth only a few pennies of steel. A smith may do it if he's using something hard to come by, like pattern welded steel. But stock removal guys just cut a groove in the blade, so they don't save anything. It's just more work.

[This message has been edited by tallwingedgoat (edited 08 December 1999).]
 
Paracelsus, isn't it possible that your friend is reading "blood groove" theories put forth with similar intent back then as they are now.


-Cliff
 
Cliff,

YES! My friend seemed to have completely accepted the (probably erroneous) idea that the fuller would help incapacitate an enemy and aid removal of the sword. As I argued for the more modern view, we both came to realize that the invention of the fuller may indeed have happened because of 'blood groove' reasoning. But maybe the lighter, faster, more torsionally resistant idea was what led to the invention. The suggestion that it helped save material sounds good also.

We probably will never know what was in the mind of the ancient swordsmiths. Regardless of the original intent, the fullers utility can be explained by an engineering mind set alone. I doubt Very much that the 'blood groove' concept really works. Have to test that one.

Paracelsus
 
Could've been an accident. Maybe some dumb apprentice swordmaker a thousand years ago made a flawed attempt at ornamentation and everyone said "cool" (or whatever was in vogue back then) and copied it ... and came up with the justifications (right or wrong) later.

Evolutionary results often seem (to me) more often initiated by accident and propagated by deliberation.

------------------
Longden Loo - Ventura, CA
Technology's the answer, what's the question?

 
Longden,

That's Exactly what I'm getting at. In biological evolution, changes just happen. Only the changes that Work survive. How or why these things occur is not so important. The ancient chinese characters for this feature in a sword translate literally as 'blood groove'. Whether they understood the engineering concepts behind the fuller will probably Never be known unless someone finds an ancient treatise on the engineering principles of sword making.

Paracelsus
 
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