Hello Vincent

The, uhh, controversy seems to be fading the last year or so......

Yeah, it got politicized for a while. Egos got involved, business interfered, but I'd say that things have kind of settled out since things were "hot".......

The thing is, we make some of this to complicated. Its not rocket science, really not.

Saying that however, there is an experience factor, and a way of relating to the universe factor. {I can't express it any better at the moment}. Some of this makes sense easily for some of us, and some of it is nonsense for many others......

Lets take distal taper, and relate this back to this conversation. Distal taper in my mind, is the easiest, most obvious way to control the distribution of mass, and how things come out on the finished sword. But its worthless if it doesn't work well with the rest of the factors that make up a sword, or make up "the distribution of mass".......

One of the things the last four years or so, is how secretive distal taper is done by some parties. Then someone will come up and say "The AT1312 I have handles just like the Albion Knight I have"....... Funny thing that.....

Then someone else will try and make a XII, and its too floppy, or too heavy, or whatever....doesn't work........

The words that are written on the function of the sword, can be educational, but in something so small as a thread, or an article, even the best do not leave enough info to help someone not already making swords, to make good swords. Too much left out, even when there's no intent to so.......

To try and bring this back to center of gravity...... I look at the center of gravity as a symptom, not a function. Its something you can see and measure.... but its not all that telling in the function of a sword...... and I think its a worthless measurment when talking about "typical".......

Its a statistic people want to see. And since much of what we do is on the internet, it probably has some value..... its not like we can walk up to a stall on a street corner, and handle several.......

One thing that occurred to me overnight is that our physical training is presumably quite different from that of the medieval or pre-medieval warrior. Most of these people were not just swordsmen - they were just as likely or more likely to be used to the use of weapons like the axe, mace, or war-hammer that placed the mass and PoB/CoG way out from the hand. I have not tried this myself (perhaps people in the reenactment community have) but one can easily imagine that if your muscles are trained to swing an axe, then a sword with a 7" PoB would have to feel pretty nimble by comparison.

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From a scientific point of view (sorry, that's my day job) swords are not that complicated when viewed in isolation - they are essentially rigid bodies that are capable of rotating and translating through space. But it gets hellishly complicated to describe the kinematics and dynamics of sword control once you attach them to a hand and have them moving through space in an gravitational/internial system.

The PoB comes into play for producing both types of movement (rotation and translation)....if you want to translate the blade through space by applying a force, the the farther this force is placed from the PoB then the more counter-rotation you will produce due to the intertia of the material on the oppostie side. So you have to produce a slight counter-torque to keep the blade from rotating.

If you want to rotate the blade, you need to apply a torque to overcome the rotational intertia and forces of gravity acting on the blade. Again, the fruther the hand is from the PoB, the more gravity is going to produce a 'helping' or 'hindering' effect in a direction-dependent manner. But that's not the only problem - even if your hand is right on the PoB, then the inertial of the blade will resist rotation depending on the distribution of mass about that point. So, let's say you make a war sword with a long handle and big pommel so that the PoB is right in your hand, its still going to feel sluggish due to all that mass way out there.

Most sword moves involve both rotation and translation , and this relates back to biomechanics. Joints only rotate, but they can translate the hand becaus the muscles apply torques about them and they are linked through rigid bodies (the arm bones). As one goes to rotations at the wrist, the elbow, to shoulder, there's a gradient of going from more sword rotation to more sword translation, because the biomechanical point of rotation is getting further from the sword, but the muscles are also getting stronger. Wrist rotation will give the fastest sword rotation, but the wrist is also weaker. For these various reasons, for a given weight, a sword with a 'good' PoB and mass distribution seems easier to swing with the wrist, whereas its easier to swing with the shoulder in the opposite case. (I'm not even touching on balance, posture, vision etc - and worse yet,, the muscles, nerves, and brain structures that control all this).

Then there's the cost-benefit function between 'handle-ability' and damage produced, which depends on a whole other set of physical factors that I won't get into here. I have heard it said that velocity is more important than mass, and this is true in a sense, but only within limitations. Muscles can only contract so fast. There's a reasons why its easier to chop down a tree with an axe than a rapier, even if the rapier didn't break.

I have been glancing at this site for years, and I know that many of you have considered these factors, just using a different language than we would use. But when it comes to complicated - yeash...take it from someone who has spent the last 20 years trying to understand simple things like eye rotation and pointing, the science of sword control is way more complicated than rocket science. We have rockets, but we don't have robots that can fence. Assuming there was funding for such a thing, I bet I could put an army of PhD students on this topic and they wouldn't solve it in 100 years.

I think my cold is getting better... time to get back to work.

Well one way of dispelling a marketing metric that doesn't work is to create a new one. :-) So perhaps we, as a community, can come up with another type of marketing rating, and quantify it, when someone else mentions a sword's POB.

Otherwise POB will continue to be used by laymen and others as a metric, despite its inaccuracy. Maybe a use oriented a number to reflect a sword's preferencial use for either thrusting or cutting. Maybe a mathematical formula could be used to generate a number based upon several factors in a sword's construction, such as weight, POB, node placement and distel taper degree.

People will always try to create a metric to better understand things they can't conceptualize. As knowledgeable people in the study of swords though it should be our job to come up with metaphors, information and ideas that can better express to other people the whole idea of what makes a sword a good sword. Perhaps some of you in the industry who produce them could come up with a metric, or series of metrics, that common consumers can grasp and use in place of POB.

Just my two cents of thought...

J.D.,

J.D. Crawford wrote:

From a scientific point of view (sorry, that's my day job) swords are not that complicated when viewed in isolation - they are essentially rigid bodies that are capable of rotating and translating through space. But it gets hellishly complicated to describe the kinematics and dynamics of sword control once you attach them to a hand and have them moving through space in an gravitational/internial system. [snip]

Of course you are right, but here the complexity does not lie in the sword, rather in the user. Fencing is immensely complex to model mathematically because the moves and reactions of the human body are hard to model and understand, sword making is immensely complex because of the craftmanship involved. However, the sword in itself (and most hand-held impact or cutting weapons) is really a simple object dynamically, that enhances our capacity and complex motions. Simple and effective, that's the beauty of the thing. I suspect that if we had boxing robots, it wouldn't be so difficult to make them fence.

As you said swords could be considered as solid bodies, and I tend to view them as 1D as far as mass distribution is concerned, so in effect what do we need? Mass, inertia, positions of both ends with respect to the CoG, and that's about it for the sword itself... Next thing you need is an idea of how the forces are applied to the weapon, and I think that it is already quite precise to consider that they can be applied at two spots (both ends of the handle). So we are looking at what, more or less 6 independent parameters? I stand by the fact that it is quite simpler than a rocket :)

Now, finding how to combine these to get stats that are intuitively linked to handling is the hard part. But it cannot add complexity... At worst it will always be 6 numbers. Either that or the stats will have relations between each others.

While I'm there, I'll react to Bryce's observation, that are really spot-on:

Bryce Felperin wrote:

People will always try to create a metric to better understand things they can't conceptualize. As knowledgeable people in the study of swords though it should be our job to come up with metaphors, information and ideas that can better express to other people the whole idea of what makes a sword a good sword. Perhaps some of you in the industry who produce them could come up with a metric, or series of metrics, that common consumers can grasp and use in place of POB.

I did propose such metrics in this post. It's exactly the kind of combination leading to more intuitive stats that I was referring to above. Truth to be told, I have changed the set a bit, but I kept the basic ideas...

Problem is, given that I'm neither a famous swordsmith, nor an accomplished martial artist, nor a respected scholar of the sword, I clearly lack the credibility to set an industrial standard ;)


Since the thread is about the PoB, I should point out that the fourth stat I describe in the post above (what I call "blade mass" for lack of a better term) is a very satisfying way to link the PoB's position to the handling. A pivot point is needed, but the benefits are clear.

Here is a little experiment that I find enlightening about the PoB. If I take one of my hammers and my rapier in a fist grip (not proper for use, but it's for the sake of the demonstration), both center of balance end up at the same distance from my lead finger (approx. 4.3in). Does that make my hammer a proper rapier? Certainly not. It's not even a question of length, the difference in balance can be felt without opening the eyes...

In that case, my stat for "blade mass" would give a result close to 1 for the hammer (nearly all the mass in the head), but less than 0.1 for the rapier (much of the mass is in the hilt). Of course there are other differences, but that's already something significant and intuitive, I think...

Best,

Wow, and I thought the thread ended when I was told to search the forum for other threads. I wish I had been paying more attention to this thread in the last few days.

I do wonder though, is there not any average whatsoever? I would have though that the PoB would be within some general parameters (ex. not below the hilt and not beyond halfway up the blade). I also wonder if certain schools or traditions have anything to say about ideal mass distribution. Or was it a completely personal decision of the user?