[A. Jake Storey II]

[Angus Trim]

Good luck Jake...........

Swordmakers no longer really agree on this stuff, so trying to get definitive answers should be real fun..........

One answer though, is that there is quite a variation on the theme, even in similar "type" blades. Both historically and now........

[Peter Johnsson]

Not only are contemporary swordmakers not in agreement (...this is true both of our time and in ages past I should think ), there is a great variation of these properties in historical swords.

The whole point of my post you quoted above, was to underline the fact that the functional and dynamic properties of a sword interact in different ways. (And since I wrote it I have learned new things : I would write the post above differently today.)
You can never just take one feature and say it is the most important one.
It is also impossible to give a "best" value for any feature: they depend on each other.

The task of a blade smith / swordmaker is to balance the various aspects of a sword into a combination that makes best sense for a given situation (=user + using). The more you know the functional aspects, the better you can plan your work. *But* there will always be an intuitive aspect of swordmaking. This might be the most important aspect of all. Intuitive understanding builds on experience and what has not yet been defined. A well made sword comes as much out of the subconscious as well defined conscious principles.

To learn the reasons why historical swords were made the way they were and looked the way they did, it is an excellent idea to study originals directly. Here you can see what priority different aspects had and how they interacted together.

The swordsmiths of old were experts of their trade.
I am sure quite a bit of what they did was based on tradition and intuition, but they must also have had a body of concious knowledge and been willing to experiment. Much of it applied directly to methods, working conditions and materials at hand at that time, and might not be directly applicable to us (although still very interesting and telling). Looking at an ancient sword you will get an impression of what mattered to the people who made it and used it. You can see how the precision of some of the lines and perfection of some surfaces were less important than heft and edge geometry. Sometimes you see how a beautifully chiselled hilt is mounted on a blade that is quite worn. Sometimes a very nicely proportioned blade with well defined surfaces is mounted in a hilt that is the result of rather basic craft skills.

Something to remember:
Factors as sword type, overall size and mass, point of balance, dynamic balance, vibration nodes, pivot points and edge geometry are all definitions we use *today* to describe various aspects of a sword. They are tools for our understanding. They might or migh not have mattered to the ancient smith or swordsman. Most probably, the historical swordsmith would have described his craft and his products with other words. Some of these could well overlap the concepts we use today, other would have been unique for his situation and understanding.
These terms, (balance point, pivot points, vibration nodes) are contemporary definitions. Their meaning depend on how strictly we use them. If they are applied too broadly or out of context, they will loose their meaning and be more detrimental than helpful of a proper understanding.
The sword exsists and function witout them. Our understanding depend on a personal intuitive relationship *and* precisely defined ideas.

[Vincent Le Chevalier]

Hey, I happen to have an opinion about that Well, mainly about pivots and balance point since I think their value is underestimated for reviewing swords (but if you skim through the list of my posts here, I believe you'll notice a pattern already )...

I think the main problem is that we all have a tendency to look for an ideal placement of all nodes and points, which simply does not exists. Almost every relative positions are possible, and most have been tried on some kind of weapon.

Thus the discussion about pivot points, balance point and nodes tends to evolve into a "which is best" discussion, where of course no general answer can be found (if it could it would have been long, long ago). And I feel we have almost reached the point when experienced people refuse to participate in discussions about that, because they've seen that much too often.

The problem is also that smordsmiths and sword users do not necessarily have the same approach to those concepts.

The only value of those particular points on weapons is that they allow us to communicate about the dynamic properties in more precise terms that "the balance on this sword is really good" It's important in my opinion, since not everyone has access to period originals, much less with extensive handling allowed... Moreover, many are buying swords online, without any mean of physically judging the dynamic properties. Pivot points and balance point allow for comparison without having all the objects at hand.

So I think there is great value in understanding the relation between the placement of pivots and balance points and the dynamic behaviour of the sword. I will attempt a short explanation of my theory about this so far...

There are several important points on a sword in my opinion:
* the balance point (G)
* the point of the hand that is the furthest of G (H1)
* the point of the hand that is the closest to G (H2)
* the pivot point associated to H1 (P1)
* the pivot point associated to H2 (P2)
* the location of the tip of the blade (T)

Commonly on swords you'd have H1H2 as the handle, the blade starts at H2 and ends at T. Beware that H2 might not be at the cross, especially when fingering the blade.

As to the link to the dynamic handling of the sword, here is what seems to work for me:
* the ratio H2P2/H2T represents the kind of tip control you have. For what I could gather, on thrust oriented swords you would have that ratio very close to one, maybe a bit less. A ratio greater than one seems to result in an awkward weapon. Less than one happens on cutting blade, as a result of a compromise with the other properties
* the length H1P1 gives the speed with which the sword tends to realign itself during a cutting motion. It should be proportioned to the technique and height of the wielder, I believe, to allow for energy transmission during all the cut.
* the ratio H2G/H2P2 gives an idea of the "blade mass" that you feel in motion. For an axe it will be close to one, for a sword it's less, for something like a foil it's very small. It's not a mass, note, it's more the ratio of the mass you feel in the blade over the total mass.
* The static feel could be represented by the ratio H1G/H1H2. It's something that goes infinite if your handle is only a point (logical, you cannot apply a torque with just a point force) and diminishes as the point of balance gets closer to the hand.

Typically cutting blades would value blade mass and appropriate cutting motion, sacrificing a bit of tip control. Interestingly, this kind of compromise tends to bring P2 closer to the harmonic node.

Thrusting blades tend to focus on tip control, and can have a varying blade mass, depending on the thrusting technique. A foil used with double time parries will probably have less mass on the blade than a rapier built for single time counters.

It's rare to be able to combine everything in a single sword, mainly because some properties are contradictory. If you aim at a great blade mass and good tip control generally you're going to sacrifice the speed of follow up in cuts, for example.

In the end it's just a matter of learning which caracteristics you like best, which are most important for your techniques or style, and then finding a sword that fits. Which does not mean that you should neglect the construction, the finish, the blade geometry, all being important caracteristics for cutting and durability.

One argument against the use of pivot points is that it oversimplifies the complexity of blade geometry, taper, materials, etc. But the point, in my opinion, is that precisely dynamics are simple and can be judged from the placement of pivots and balance points. On the other hand, building a sword from scratch cannot be done only with the understanding of pivot points, of course. They depend on the mass repartition which in turns depends on taper and materials... And that's why swordsmiths do not have that approach. They must study the blade profile in all its complexity, in order to get not only pivot points, but edge profile, durability, flexibility all right.

So in the end, those points are mainly helpful for users. Sword makers can still use them as a check or control, but for their task it's clearly not enough.


Okay, this post was way too long and too technical, so I'll be glad if anyone makes it to the conclusion I encourage anyone interested to experiment, even with just a stick, trying to hold it at various points. It's an enlightening experience when you realize that you can link what you feel with just a few points' positions...

Oh, and if you're looking for references, the only one I know about pivot points is the article by George Turner. I do not agree with everything in this article though, I think he puts too much emphasis on impact properties, and he too quickly concludes that the pivot point of the cross must be at the tip. But still, fairly good introduction...

Regards

[Craig Johnson]

Hi Jake

Good questions and I wish I could point you to the book that dealt with them, but there is no such reference. Actually the myArmoury archives are probably the best source for a view of this subject going through the old posts and watching for new like this and comparing the ideas and understanding and seeing what new questions develop.

Peter covered the elements of blade structure pretty well. I have not tried out Vincent's calculations myself but they look interesting and I look forward to exploring them. It is an exceptionally complex issue and one with a high enough subjective quotient that it maybe beyond the ability to represent in a numerical way. Peter's comments on intuition and well-defined specifics are crucial to getting the final results. There is a "feel" that each maker concerned with these issues will like in a particular sword and that is the sum of it all.

One area that I have been exploring that has some bearing on this is the differences felt by users in the same piece. There is a whole series of things that come into this but it boils down to a sword is only as effective as its GGI.

What is the GGI you ask? It is the swords Ground Grip Interface. I am not trying to be to flipant here as the hand on the grip really has control of how well a sword works. The fact that swords are hand tools and that they work only as well as the hand on the grip can make them work is crucial to remember in comparing swords. This simple element has far more to do with the success of a performance sword than any physical aspect of a relatively well-made replica or original.

It will include such things as moment of inertia, grip style, strength, muscle tension, skill, hand eye coordination and a multitude of other factors. As a period maker it may well have been a goal to produce a solid well built forgiving sword capable of letting medium grade users get the most out of it as opposed to high end supped up models who needed to be handle just so or they would react badly.

Just to add to the idea here is a graphic representing the physics principles that would be involved in studying the swing of any particular sword by any particular swordsperson.

Best
Craig

[Angus Trim]

When we get into these discussions, its real easy to go into to much detail, and get into stuff that really doesn't matter...*g*

Discussions like this are fun, but the end result is what matters, how does the sword handle, how does it perform?

When things like this were first discussed, we all generally were real sincere and sharing in our discussions, and there was a lot of shared information. We all learned a great deal.......

Over the years, politics, egos, marketing, and bullshite has entered the equation, and many of us have gotten real careful what we're willing to contribute for fear of starting a fight.........and where having an educational, fun conversation is worth it, fighting and ego clashes are not.........

You could add points of rotation to pivot points and nodes {points of rotation and pivot points aren't really the same thing}, and confuse things more..........

Are there any real concrete things in this study? Or as Craig says, is there a lot of subjectivity? I was told a couple of years ago, that a good saber has 6 points or rotation, and a good straight sword one.....Well, there are some sabers that only have two points of rotation, and while playing with a couple of straight single swords I'd been using in my Tai Chi practice, I found four points of rotation.......... Obviously things are more complex than what the person that related the "rules of saber handling" believed at the time.

When studying antiques, and the properties thereof, one needs a certain caution....... Is the sword being studied a top notch example? Or is it perhaps a less than top quality piece {compared to others made at the same time}? We can't really know because we weren't there at the time...... all we're really doing now is studying, and drawing our own conclusions...........and if we're intellectually honest, we must admit that at times we may be drawing a conclusion from insufficient evidence..........

Today, the sword arts consist of arts that were still "live" during the early twentieth century, a few Japanese and Chinese arts, some arts being rebuilt from evidence {Western and Chinese}, and some made up arts. Some of those still living may have changed for whatever reason during the last century, and no longer really resemble in all ways the way they were taught during the time an individual may actually have to fight with a sword........

And we're studying swords, with this as a background. That, and modern perceptions that Hollywood and modern "reenactment" have given us. Our knowledge is constantly growing, and at times {even though I hate to say this}, is flawed because of marketing and politics.........As we discuss, share, and learn, all of us should remember to take things with a certain grain of salt. Five years from now, things believed to be the "truth", might be seen differently...

As Craig points out, there's other things in the mix too that need to be considered. He mentions handles, and then has some fun with that.....*g* Another thing left out so far, is the operator of the sword. With subjectivity involved, things can change when comparing a sword, with two persons different backgrounds and perceptions..... one might find a sword cuts real easy, the other might use the sword as a baseball bat............

[Jörg W.]

After reading a lot on weapon dynamics on myArmoury and swordforum I almost gave up on trying to get a clue. Discussions were just too controversial, as Angus noted, and my knowledge of physics maybe too small. Still I cant get around fresh posts on this topic.
Vincent gave some points that I would love to see reasonable comments on. I think that a lot sword smiths rely much on their experience and intuition. But as an engineer and in times of CADCAM I am not satisfied with that. It doesn’t have to be numbers. Let’s start with Okeshott’s types and their difference in design and use. I’m talking about the typical swords one would have seen a thousand times on the battlefield, not a special one made for an individual person. I would like to know how modern sword designers start to design a type of sword and how they define its characteristics. I can hardly believe that it’s all about trial and error (that would take too much time and money). For example, you can increase recovery speed of an XVa by shifting the CoB backwards by adding mass to the pommel, enlarge the grip, add more taper to the blade…(?) According to what I read you change half of the other notes and point in either way too. So how is it done best without getting odd dynamics?


P.S. I hope that proving these information doesnt touch anyones business secrests.

[Vincent Le Chevalier]

To answer Gus's question, I find at least one real concrete thing in all those study, and it is the sword The sword exists even if there is no one to handle it. The sword, as any object, is subject to the laws of physics.

Of course, the "performance" with a given sword will depend on the person handling it. That does not mean that there is nothing absolute we can say about the sword properties. Imagine that I lend my car to a rally driver. I'm quite sure it will perform a lot better than when I drive Does that mean that the engine, weight, direction, etc. of my car have changed ? Of course not. It's just that the person driving it takes advantage of those better than I do. Imagine that I lend my car to someone that is as poor a driver as I am The car will likely perform differently, though maybe not better, and still it has not changed. There are properties of my car that belong to this object, and that do not change as the driver change.

Same goes for weapons. When I lend my boken to someone else, it's not used as I use it. Maybe it performs differently. And nevertheless it's the same, and there are things I can say about it that do not change. And still its performance, and the feeling of the person, are linked with those properties.

Having said that, and considering the sword as an engineer, there is a model that I find reasonable, and that's a long solid object, with a given mass distribution. And it happens that the motion of such an object depends only on the forces applied (that would be what differs from person to person), and on the mass, center of gravity, and inertia of the weapon. Pivot points reflect just that last property.

Now, I agree that my calculations aim at quantifying subjective properties. I've chosen those ratios because they concur with what I feel. You could define other ratios... In fact, I'm eager to hear input from people trying my calculations (and by the way, Craig, if you have time to explore, please share any comments or results...). Even if it's to say that it plain does not work, if there is an example of why I'm glad with that. But from those ratios, you can still go back to the basic, physical quantities of inertia, center of gravity, length. The engineer part of me screams that they have to be significant

What makes me sad is that those basic physical quantities appear almost nowhere for the time being. I can't think of any reason why. Well, for period originals I would understand, because you may not be able to undertake any measurements you like. But for reproductions ? Gus's answer seem to point out that it became political... I don't really have the background or reference to understand exactly why, nor when. But I think we are setting aside a good deal of knowledge, just for lack of measurements. I'm at the point when I'm really looking forward to buy another quality sword, partly because this is the only way I have to gain a physical insight about the object (and greatly because swords are just lovely but it's a common attitude around here ).

For those interested in understanding the concepts hiding behind Craig's graph, it comes from the HyperPhysics site. But note how much of these bubbles link to center of gravity, moment of inertia and their interactions with forces. It's really here that the secret of motion lies...

Best regards

[Angus Trim]

[Jörg W.]

Thank you, Angus.
I understand that you chose a blade length and base thickness. Together with the sword type (giving an idea of the profile taper) you can choose the distal taper with regard to the aimed mass and CoB. Of course you can change the last two by adjusting any of the given factors or even later on by assembling a proper handle and pommel.

Still I don’t get your point here:

[Angus Trim]

[Peter Johnsson]

Vincent,

I like your use of ratios. My approach is similar, but I do not use ratios of these aspects.
I will try this out and see what results I get.
I think it could be a good way to illustrate how these things work together.

Here are some examples of how these aspects interact, and what they do:

Pivot points result from the distribution of mass in the sword. Length and volume is what counts here.
In every thinkable location in the grip, there will be a corresponding pivot point in the blade. To lend some system in this (when I document and make swords), I especially note:
-Forward pivot point = in the grip just behind guard and its correspondng point in the blade.
-Aft pivot point = in the grip just inside the pommel and its corresponding pivot point in the blade.

How far apart the corresponding pivot points are placed in the blade depend on how much the mass changes in the blade and how long the grip is. If the change is dramatic and the grip is long in proportion to the blade, the pivot points will be far apart. If the change is moderate and the grip is short, they will be close together.

Pointy longswords will by nature therefore have a forward pivot point close to the point (at the point or a short distance behind it) and the aft pivot point a distance behind the blade node (or close to the middle of the blade).

The effect this have is that when the forward hand lead or guide the sword in wards or guards, the point will tend to stay still centered on target, but when the second hand (normally the left) comes into play more strongly, as in cutting, the sword will tend to rotate rather more around the middle of the blade.
In effect, this makes it easy to keep the point on target in warding swordplay, but also effectively shortens the amount of blade you need to move in circular motions as you prepare and deilver cuts.
This is the reason why the pointy longsword feels so versatile and manouverable.

Swords that have short grips in proportion to the blade normally have the forward and aft pivot points closer together, and often placed on each side of the blade node.
This helps make such blades manouverable in circular swordplay.

A rapier, you would expect to have to forward pivot point placed close to the very point, since point control is important, right?
Now, the interesting thing is that they tend to have forward pivot placed somewhere in the middle betwen blade node and point. I was mystified by this at first, whe I started to note this on well preserved rapiers of good quality.
After some time it dawned on me that since the rapier is often used in contact with another blade to turn away attacks and deliver attacks, it is really useful to have a blae with a natural tendency to rotate at the area that will see most contact with an enemy blade.
This placing of pivot points also helps in certain cutting actions of long rapier blades. Difficult to explain in text. You need to try this out with a well made rapier that has a nice and light point: Notice how it moves when you deliver wrist cuts in front of your body.

These are just a few examples why pivot points will tend to be placed differently on different types of swords.

Placing of pivot points will largely depend on the overall proportions of a sword type: long heavy blade/short grip, Long grip/long light blade, short grip/long light blade...All will lead to certain typical configurations.
You can adjust the placing of pivot points just like you adjust balance point: by varying the length of the grip, and the weight of the pommel.
A small shift in balance point might, if the blade has a slim point section, yield a rather dramatic shift in forward pivot point.
A blade with less dramatic change in mass: less dramatic distal taper, will be less sensitive to changes in pommel weight. You will have to add a really heavy pommel to get the forward pivot point anywhere close to the point on such a blade.

There is also some interaction between cutting performance and placing of pivot points. The blade node, COP, and the spacing and placing work together in defining a length of the edge where the bite will be most effective. But, again, more factors come into play. Not the least, like Craig so rightly said: the swordsman!

It is not as easy like point control is always the effect of a forward pivot point close to the point. In long swords it helps, as they are used in such a way that it makes a difference. In a rapier it matters less (and might even be detrimental!). Mass in the point and the overall mass and size of the sword and the shape of the grip also plays a part.

Hey Gus!
Now, what I am really curious to know is the difference between rotation ponts and pivot points!
It might just be one of those cases where there is a difference in definition and use of words. I just don´t get it.
To me the functions of pivot points make a lot of sense: I can see them in action when documenting originals and making swords.
I don´t understand the concept of rotation points. How can there be six of something in a saber, but only one in a straight sword, or four?
Gus, I would really apreciate if you could shed some more light on rotation points! Perhaps it is something I´ve already seen in swords, only not put into context like you (like the dreaded demi-nodes!). Perhaps it is an aspect I´ve not noticed before. I look forward to learning something new!
Thanks!

[Greyson Brown]

The one thing that I am still really lost on, and may never fully grasp, is: how does one identify, locate, and/or measure the location of rotation/pivot points? That may be a stupid question, but I just don't understand.

-Grey

[Angus Trim]

[Vincent Le Chevalier]

Peter,

To be honest your previous posts inspired me a good deal during my thinking, so I guess it's no wonder that there are similarities in our approaches... I'd just like to react to a few things.

[Nathan Robinson]

This topic has been promoted into a Spotlight Topic.

[Greyson Brown]

[Jörg W.]

Thank you all for your posts so far. i appreciate your effort.
we have some important pieces of the puzzle here now, i think. maybe ill need a bit time to get everything of it.
any new or recommended old pictures may be good to support the facts for better understanding.


fact is i need to handle more swords to connect theory with practice.


Greyson, the ' is an index. variables with same index are related to eachother, i assume.

[Angus Trim]

[Peter Johnsson]

Vincent:
The idea is to take the forwad node from the most forward spot you grip, so in a rapier it would naturally be in front of the guard, in most cases.
This still does not bring the blade pivot to the very point. At least not in those I´ve seen.

Gus:
I won´t be in racine next year. It was only that one time, years ago.
It would be really nice to something more about rotation points as they mystify me.
Or is this possibly a secret ?