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Forum Index > Historical Arms Talk > Balance points, pivot points, and nodes on the sword. Reply to topic
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A. Jake Storey II




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PostPosted: Mon 16 Oct, 2006 9:32 pm    Post subject: Balance points, pivot points, and nodes on the sword.         Reply with quote

Peter Johnsson wrote:
The COP is usually identified with the placing of the node of no vibration of the blade.
To me the nodes on no vibration offer a way to manipualte the stiffness of the sword during a cut. In popular understanding this has to do with the concept of "harmonic balance". As time has gone by, this term has been stretched to cover so many different aspects of a swords performance, it has almost lost its meaning. When vibration nodes are in focus I personally prefer to talk about node placing, as this is a more precise description.
It seems that a common notion is that the placing of the blade node is of great importance for the cutting performance of the sword. I am not so sure about that. I do not think the blade node and the COP are the same thing. They may coincide, but this is just coincidence resulting from other aspects of the design of the sword.
I´d say it is more important to note where and how the vibration nodes are placed in the grip, or hilt area.

Try this out:
Grasp the grip of the sword and hold it point upwards. Tap with the heel of your hand untill you find the node of the blade. You will notice how the whole blade becomes stiff and vibrates less as you tap in the spot where the node is. From a wobbly flexible blade it suddenly becomes more like a stiff plank.
This offer us a clue to why the nodes play a role in the design of swords.
The node is a place of stiffness where you can manipulate the rest of the sword without causing vibrations. Hence it seems to me that the nodes in the grip, that you will always grasp, are more important than the nodes in the blade. I say node*s* since there are vibrations of higher pitch with nodes placed on each side of the primary nodes in the blade and grip. These are not always aparent, but can be used to some effect in stiffening especially flexible or long blades.
When cutting with a sword during an "agressive encounter with an enemy" you will not only use the part of the blade where the node is, you will cut with a longer section both inside and outside the blade node. *But* you will always grasp the the hilt in much the same place, and by doing this you impart highest possible stiffness in the blade druing a cut, if the placing of the nodes in the grip are optimal.
Again, one must be aware that this is not a rule that has precedence over other aspects of the function of the sword. I have seen (original)swords that have their grip node placed *in front* of the guard. A strange and confucing thing to us modern aficinados, but it sems to work on certain types of sword. One of my most agressively cutting swords had the "grip" node placed 10 mmin front of the guard. This is clearly not according to the rules of how things should work. My guess is that the secondary nodes are put to good use in these instances. More research is needed here.

COP has more to do with pivot points, and this is something else completely from vibration nodes.
The no-shock effect that good swords are associated with is less an effect of the placing of the vibration nodes than the correspondence between pivot points in the grip area and the blade. (both these work together to some extent, but the vibration nodes are primarily an aspect of stiffness and only have a secondary effect on shock dampening)

Placing of pivot points also have a big effect in the intuitive feel of the sword and what part of the edge/blade you get a direct dynamic feedback on through the hilt as you move the sword.
-A feeling of "floating in the air" and "extention of my arm", is a result of effective use of the pivot points.
-Does the blade pivot close to the vibration node as you move the hilt back and forth from guard to guard, or does the point seem to hover still in the air without moving from side to side even as you shift guard? You will see both these situations and everything in between on different types of swords. This is something you adjust according to the intended function of the sword.
These are very important charactersitics for the feel of a sword. Much more important than where the balance point happens to be placed. (although this will of course have some effect as well).

Of course Point of Balance, Placing of Nodes and Pivot Points all correspond with each other.
If you want to shift one aspect without moving the others too much you need to work with the shape/dimension of the blade or lenght of the hilt.

So, my take is this:
Just as the placing of the balance point used to be a main concern some years ago, now there is a focus on where the nodes are placed. Both these aspects will tell you something of how a sword feels and performs, and are important in their own right, but they do not tell the whole story. The key to the dynamic balance, or intuitive feel of a sword lies in the placing of the pivot points. These also has a lot to do with how a sword delivers a cut. Pivot points, Node points and balance point are all spearate entities, but do have an effect on each other.

If you want a sword that is more forgiving in what section of the edge you can use for best cuting reults, you want a sword where the corresponding pivot points from the grip are placed far apart in the blade.
This is difficult to do in a slim and flexible blade with little variation in the distal taper. This is one aspect that non-linear distal taper hepls in more ways than one.

By corresponding pivot points I mean this:
imagine the part of the grip you hold that is closest to the guard, or most forward to the point. If you grasp this place sideways (edge to edge) between your thumb and index finger in a loose grip and "wiggle" the sword back and forth you will notice there is a section of the blade that hangs still without wiggling. This is a bit similar to finding the spot of no vibration in the blade, only that you do not slap the pommel. Instead you move the grip back and forth in a loose grip so that the part you hold can pivot between you fingers. (this is a quick and dirty way of doing this, but it works)
You will find that the corresponding pivot point in the blade from the piovot point in the front part of the grip is placed somewhere between the vibration node and the point. Depending on how far towards the point in the blade this pivot is placed the sword will offer more or less precision in its point controll.
If you now grasp the grip where the heel of your hand typically is when you wield the sword and repeat the wiggle test, you will find there is another pivot point in the blade closer to the hilt that correspond to this place futher back in the grip.

You have now established where the extreme grip pivot points in the grip have corresponding pivot points in the blade. Typically there will be a longer distance between the pivot points in the blade than the distance between the pivot points in the grip.
This will tell you roughly where you will make the most efficient cuts. But do not take this too far as there are other factors having an impact on this as well.



O.K., I have known of the existence of balance points on swords for a long time. What i didn’t know is haw varied they were. I also was entirely ignorant of nodes and pivot points. I’m simply wanting to know from people who know what there talking about more details about them. Like, I always assumed the the balance point was just infront of the hilt, but allot of swords seem to have them several inches away. When I was younger, me and some friends would have sparing bouts with swords made of steel and aluminum alloy (mostly aluminum) pipes that had all except a 10” section at one end flattened to mimic a blade. This were pretty cool, and the fact that you could get hurt with them was one reason we really liked them. After learning about Balance points, I filled the hallow handle with some peases of steel until the balance was right infront of the hilt. At first I thought it was awesome cause i could move my blade around faster then my friends, but I quickly found that when trying to block my sword would usually get knocked around allot instead of being any good at deflecting the sword or stopping it. My point? What is the best placement for what kind of blade? I want to know more about the the structure of a blade.


P.S. Though I will not be able to buy anything for a wile do to a low income job. Some books that give some details would be cool to. I mite be able to find them at a library.

P.P.S. Some of you might recognize me from the Straight vs. Curved thread, what would the deference in the balance points, pivot points, and nodes be between straight and curved swords?

Only you can deny yourself your rights.
Too ignore the rights of others, is to forfeit you own!
Thereby, in your crime, YOU bring Justice on your own head!!!


Last edited by A. Jake Storey II on Mon 16 Oct, 2006 10:10 pm; edited 1 time in total
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Angus Trim




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PostPosted: Mon 16 Oct, 2006 9:54 pm    Post subject:         Reply with quote

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........

swords are fun
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Peter Johnsson
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PostPosted: Tue 17 Oct, 2006 2:10 am    Post subject:         Reply with quote

Not only are contemporary swordmakers not in agreement (...this is true both of our time and in ages past I should think Wink Razz ), 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.
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Vincent Le Chevalier




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PostPosted: Tue 17 Oct, 2006 5:38 am    Post subject:         Reply with quote

Hey, I happen to have an opinion about that Happy 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 Wink )...

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" Happy 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 Big Grin 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

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Vincent
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Craig Johnson
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PostPosted: Tue 17 Oct, 2006 8:05 am    Post subject: Complexity +         Reply with quote

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



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Angus Trim




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PostPosted: Tue 17 Oct, 2006 10:42 am    Post subject: The contrarian viewpoint         Reply with quote

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............

swords are fun
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Jörg W.




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PostPosted: Tue 17 Oct, 2006 11:44 am    Post subject:         Reply with quote

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. Big Grin 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.
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Vincent Le Chevalier




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PostPosted: Tue 17 Oct, 2006 11:49 am    Post subject:         Reply with quote

To answer Gus's question, I find at least one real concrete thing in all those study, and it is the sword Happy 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 Happy 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 Wink 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 Happy

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 Razz ).

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

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Vincent
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Angus Trim




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PostPosted: Tue 17 Oct, 2006 12:35 pm    Post subject:         Reply with quote

Jörg W. wrote:
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. Big Grin 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.


Hi Jorg

I'm not going to try and answer everything, and I'm only going to answer from my perspective......

{And start with an aside.... Craig and I talked about this thread just a while ago, and hoped it would take on a life, actually take off on its own....... looks like it will, and I hope it takes more than one direction}

I started as a "sword reviewer", and since I'm a machinist, I tended to take things to their basics, the numbers. And I wrote about them, shared them. And even before starting making swords, I collected "specs" of various swords. In the last seven years, I've seen, handled, measured several antiques, but even so, I have collected many more "specs" than swords I've actually seen {folks would measure antiques, send me their measurements}. Some specs are very good, some rather incomplete.........

The next thing along the line, was looking at the way a blade tapers. Distally and profle. When I started, there weren't many reproductions that did distal taper right, so the only way to look at distal taper, was thru antiques, and or specs of antiques......

The next thing then was make something and try it out. Make, say, a Xa that distals linearly..... and make one where the distal taper is concave.......then go from there......

There's a lot of things I made 6 and 7 years ago, that are no longer available, and that may not have anything to do with historical accuracy. That may have something to do with the way the sword handled and performed once finished........

One can write an encyclopedia about the importance of distal taper to a blade, and still not cover it all.

Some types of blades though, kind of demand a certain distal taper....... And the type of distal taper might have something to do with the thickness at the base that you intend to start with, and what it is that you're trying to accomplish........

To give an example, I designed my AT1211 around the requirement of being light, short, very handy, and decent cutting. I wanted to start the thickness at about .19 to .2 inches thick {approx 5mm} because of the number of type X's that start at that thickness.... and I wanted it to be rigid enough to cut plywood well {shields, don't you know}......

That meant that for a 28 inch blade, a concave distal taper probably wouldn't give me what I wanted..... and a convex distal taper might be too heavy and blade heavy for what I wanted........ so this one wound up the dreaded "linear distal taper"....{why folks look down on linear distal taper, I'll never understand, there are a lot of antiques that have "linear distal taper"....}

Oddly enough, the sword wound up a great little cutting sword, very handy in the hand. Weight, 2lbs..... and it cuts plywood {and everything else reasonable} very well...... It also distal tapers very similarly to X.10 seen in"Records" and currently part of the Oakeshott collection........

I didn't do this exactly for "historical accuracy", because many existing type X's have cogs way down the blade. And the average 21st century buyer wouldn't be interested in a sword that handles like an axe, no matter the historical accuracy.......

The blade geometry is accurate, the weight, balance, etc, but its not close to the "average" of existings antiques, nor of the specs I have for swords of this type. The harmonics, dynamic balance, etc though, are right where I felt they should be when I first designed the sword..... and they still are right on for what I look for today........

When designing a sword for today's market, one has to decide where one is going with it. Historical accuracy may be important, but there's such a variation in each type, that there's quite a variation in historical accuracy.......

When designing for "type", one always designs with one's own perspective as part of it. We all interpret "type" somewhat differently, and you'll see that in what is designed, and in these conversations.........

As far as designing for node placements, etc..... I no longer really remember exactly what I was thinking five to seven years ago. I do know, I've always wanted the main handle node in a short range per type, and ussually expected the demi-nodes to be in certain positions too. Getting that right ussually means the rest of the sword blade falls in place too....

One needs to decide what criteria to design for, and then stick with that criteria. Sometimes one has to modify things and redo, this still isn't an exact science. I don't think it ever will be...........

As far as "secrets" go, today I think its kind of a waste of time trying to keep secrets. Swords can be bought, and "reverse engineered" so easily it isn't funny. A sword isn't a rocket, and sword making isn't really rocket science. Sword making for the western market is global today, we get swords into the North American and European markets from Pakistan, India, the Phillipines, Australia, New Zealand, China, Korea, the US, Canada, and most of the European countries...........anyone can buy a sword, and copy certain aspects of it.........

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Jörg W.




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PostPosted: Wed 18 Oct, 2006 8:42 am    Post subject:         Reply with quote

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:

Quote:

"I do know, I've always wanted the main handle node in a short range per type, and usually expected the demi-nodes to be in certain positions too. Getting that right usually means the rest of the sword blade falls in place too...."


..in a short range per type.. demi-nodes..
Maybe it’s just my bad English. Would you mind to say that with other words again, please?
Does that mean that you usually don’t have to change anything for placing the vibratory nodes, after main designing process? How would you do it if it were needed anyway?

When talking about (medieval) sword types I’m thinking of Oakeshott’s typology. Sure swords of same type can be very different, but there are some basic ideas, determined by its common use, that people agree on. (XV is rather a stiff trusting sword of diamond cross section)


Sure, sword making is no rocket science; still there are rather few companies that include distal taper in their designs. As most sword types need distal taper ill stay with the quality reproductions of the west.


Vincent, nice to see there are others that like numbers and ratios, too. Wink I wouldn’t judge a sword on these alone, but they can give good information when interpreted correctly.
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Angus Trim




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PostPosted: Wed 18 Oct, 2006 10:15 am    Post subject:         Reply with quote

Jörg W. wrote:
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:

Quote:

"I do know, I've always wanted the main handle node in a short range per type, and usually expected the demi-nodes to be in certain positions too. Getting that right usually means the rest of the sword blade falls in place too...."


..in a short range per type.. demi-nodes..
Maybe it’s just my bad English. Would you mind to say that with other words again, please?
Does that mean that you usually don’t have to change anything for placing the vibratory nodes, after main designing process? How would you do it if it were needed anyway?

When talking about (medieval) sword types I’m thinking of Oakeshott’s typology. Sure swords of same type can be very different, but there are some basic ideas, determined by its common use, that people agree on. (XV is rather a stiff trusting sword of diamond cross section)


Sure, sword making is no rocket science; still there are rather few companies that include distal taper in their designs. As most sword types need distal taper ill stay with the quality reproductions of the west.


Vincent, nice to see there are others that like numbers and ratios, too. Wink I wouldn’t judge a sword on these alone, but they can give good information when interpreted correctly.


Hi Jorg

I just lost a really long, detailed post, probably because it timed out since I was writing and keeping a machine running at the same time......... I'll get back later as time permits.

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PostPosted: Wed 18 Oct, 2006 12:20 pm    Post subject:         Reply with quote

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!
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Greyson Brown




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PostPosted: Wed 18 Oct, 2006 12:41 pm    Post subject:         Reply with quote

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

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Angus Trim




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PostPosted: Wed 18 Oct, 2006 1:18 pm    Post subject:         Reply with quote

Jörg W. wrote:
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:

Quote:

"I do know, I've always wanted the main handle node in a short range per type, and usually expected the demi-nodes to be in certain positions too. Getting that right usually means the rest of the sword blade falls in place too...."


..in a short range per type.. demi-nodes..
Maybe it’s just my bad English. Would you mind to say that with other words again, please?
Does that mean that you usually don’t have to change anything for placing the vibratory nodes, after main designing process? How would you do it if it were needed anyway?

When talking about (medieval) sword types I’m thinking of Oakeshott’s typology. Sure swords of same type can be very different, but there are some basic ideas, determined by its common use, that people agree on. (XV is rather a stiff trusting sword of diamond cross section)


Sure, sword making is no rocket science; still there are rather few companies that include distal taper in their designs. As most sword types need distal taper ill stay with the quality reproductions of the west.


Vincent, nice to see there are others that like numbers and ratios, too. Wink I wouldn’t judge a sword on these alone, but they can give good information when interpreted correctly.


Hi Jorg

I'd intended a longer response, but I'm time constrained today, and the timing of the "drop" will not let me type this in, and keep the Navy work running.

So, I'll have to get more complete on the nodes later......

Just quickly on a sword like the 1211..... any short singlehand cutting biased sword I make.

I want you to understand, that this is just the way I do it.......

As has been mentioned many times, its the blade itself that makes for node positioning and dynamic balance. The hilt can kind of "tune" it, but the character of the distal taper, profile taper, blade contour, edge geometry etc, will already have laid the groundwork for the finished sword. A pommel just "tunes" it. A pommel, weight and or shape, will modfiy the positioning of the nodes, and also affect the dynamic balance. The node and dynamic balance may be different things, but both are affected by changes to the blade, and affected nearly equally...........

On a sword like this, I have a formula, and I like to position the "secondary node" {or primary handle node} right under the index finger, right next to the guard. Ussually, when you do this, you have a very obvious demi-node further down the handle.

With my formula, then the handling characteristics will be at what I consider nominal, and so will the cutting characteristics. Demi-nodes will quite often be moderately obvious when looking for them............

A blade {including tang} has two nodes, and then there are four deminodes, and it splits again to eight, etc...... Beyond the deminodes, we reach a point of "over analyzing", and "don't really matter"........

The interesting part of things is how this is related to the dynamic properties, ie the pivot points, etc.....

Peter

I still owe Jorg more on the nodes........ time permitting and this thread staying live long enough, I'll get to it......otherwise, see you in Racine next year........

Gus

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Vincent Le Chevalier




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PostPosted: Wed 18 Oct, 2006 2:29 pm    Post subject:         Reply with quote

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.

Quote:
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.


Makes sense to me. The main difference between our approaches is that I do not necessarily think that the forward pivot point should be associated to the end of the handle, but rather to the end of the grip (but I'll develop on the difference later about rapiers). Same goes for the second reference point since the pommel could be grabbed as well. The thing is that in that case, it makes less of a difference since the reference point (the end of the grip) is further away from the center of balance, so the location of associated pivot point, and the distance between them, is less sensitive.

Quote:
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.


I cannot agree more Happy I want to thank you for this explanation since it's exactly how I think about these things. To have my hypothesis (yeah, because it's not like I have plenty of longswords at hand) confirmed by someone who has seen, handled and built that many quality swords is really, really comforting. I feel I haven't been wasting my time thinking about all that Wink

Now on to rapiers,

Quote:
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.


I think that's were the difference between the geometric extent of the handle and that of the grip becomes significant. Not that I disagree with your analysis, but I'd like to propose another one...

If I understood correctly, on rapiers, you still take the forward pivot point as that associated with the end of the handle, just behind the cross. What if you take the pivot point associated with the index ? When fingering the blade, I believe there could be as much as an inch of difference between the index and the end of the grip. This difference in the reference points, so close to the center of balance, can translate into a difference of maybe as much as 20cm of distance between the pivot points (I'm making the number up here but the idea is that the pivot points can be really different). Now, I think everyone agrees that fingering tends to augment tip control. So maybe the pivot point of the index finger is still at the tip ? The difference with the longswords' case being that the index is not precisely at the cross.

I don't have a true rapier (though this problem is bound to be remedied sooner or later Wink ), but that is the effect I noticed on my Milanese Rapier, that I consider more a cut&thrust sword. On true rapiers this effect might be amplified. I'm really curious of what you think about this idea...


And to Greyson,

The measurement of pivot points is really easy when you have a bit of practice. I am now almost able to spot pivot points with my eyes shut only through what I feel of the motion of the weapon...

But here is the method that I like best. You should hold your weapon very softly, ideally between two fingers, at the chosen point of reference. Let it rest point down. Now, you have to start making back and forth motions with your hand, still holding the weapon of course, but without applying any torque. The faster you can, the better, but be wary not to hold the weapon to tight. During those motions, there should be a point on the weapon that does not move. This is the pivot point associated to the chosen reference point. You can repeat the measure at any reference point you like.

If you are unable to grab the weapon satisfyingly at the desired reference point, you can use an other couple of reference/pivot to deduce all pivot points.

Say that you were able to find the location of the center of balance, G, and a pivot point P associated with a reference point R. Now, you'd like to find P', the pivot point associated with another reference point R'. You can use the relationship :
RG*GP = R'G*GP'
This product of distances is the same for any pair of pivot/reference point. It's also the moment of inertia of the weapon divided by its mass... That allows you to locate all the pivot points you like.


If anyone is interested, I can describe a geometrical way of finding pivot points as well. In fact I even built a device in paper (looking strangely like an astrolabe...) to allow me to compare the pivot points of most of my weapons without having to carry them with me everywhere Razz

But that's another story and I should really be getting some sleep Happy

Enlightening discussion, thanks to everyone taking part !

--
Vincent
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PostPosted: Wed 18 Oct, 2006 3:09 pm    Post subject:         Reply with quote

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PostPosted: Wed 18 Oct, 2006 3:39 pm    Post subject:         Reply with quote

Vincent Le Chevalier wrote:

And to Greyson,

The measurement of pivot points is really easy when you have a bit of practice. I am now almost able to spot pivot points with my eyes shut only through what I feel of the motion of the weapon...

But here is the method that I like best. You should hold your weapon very softly, ideally between two fingers, at the chosen point of reference. Let it rest point down. Now, you have to start making back and forth motions with your hand, still holding the weapon of course, but without applying any torque. The faster you can, the better, but be wary not to hold the weapon to tight. During those motions, there should be a point on the weapon that does not move. This is the pivot point associated to the chosen reference point. You can repeat the measure at any reference point you like.

If you are unable to grab the weapon satisfyingly at the desired reference point, you can use an other couple of reference/pivot to deduce all pivot points.

Say that you were able to find the location of the center of balance, G, and a pivot point P associated with a reference point R. Now, you'd like to find P', the pivot point associated with another reference point R'. You can use the relationship :
RG*GP = R'G*GP'
This product of distances is the same for any pair of pivot/reference point. It's also the moment of inertia of the weapon divided by its mass... That allows you to locate all the pivot points you like.


Okay, that does help. Now that you say it, I think it has been explained elsewhere, it just didn't stick. One other question, in your equation RG*GP=R'G*GP' what do the ' represent? The last math class I took was "math for liberal arts majors," so I have not encountered the use of apostrophes in math before.

-Grey

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Jörg W.




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PostPosted: Wed 18 Oct, 2006 3:55 pm    Post subject:         Reply with quote

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. Cry Happy


Greyson, the ' is an index. variables with same index are related to eachother, i assume.
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PostPosted: Wed 18 Oct, 2006 8:09 pm    Post subject: nodes and distal taper         Reply with quote

Jörg W. wrote:
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. Cry Happy


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


Hello Jorg

More of what disapeared this morning.......and a bit more.......

Can't really talk about nodes without bringing up distal taper, and mentioning the importance of the crossection, for instance, a deep double fuller can push the "cop" node down the blade just a bit further than an identical blade with a single fuller.....

And before getting into the meat of things, another aside about nodes and durability. Years ago, I came out with a new sword where the first few sold quickly. I got one back from a local guy who'd pooched a cut and bent it, right at the cop. Then another local, same thing. Then one from out of state. As luck would have it, I had all three back within a week. All had a bend at the cop, and a "kink" close to the tip. All the warpage was within .12 inch in position on the blades measured from the shoulder..........

The position of the kink was on a deminode.......

I changed some of the dimensioning, and there hasn't been a problem again. Took note of the "ratios", and added that to my base. Since then, I've seen the same thing crop up by other makers, though not quite as extreme as my case....

The character of distal taper really depends on the type of sword, and what you're trying to accomplish. When new to this bizz, I tried some complex distal tapers, and a couple of convex distal tapers.... but today I generally stick with a concave distal taper, many different variations on the theme, or a linear distal taper. {there are a couple of exceptions}

The various concave distal tapers I use because at the time I might be trying out something special. I use linear distal taper at times depending on the profile taper, and because linear distal taper is the most versatile distal taper {though badly maligned in recent years, its actually a very good way of doing things for some types of blades, and I use it about 30% of the time}........

I really don't use these characteristics because I'm trying to manipulate the two nodes, its the deminodes I want to be able to influence as we get to the end product.......a sword that will hopefully have superior handling charateristics and performance per type {in today's world}.......

By maniputating these, I am manipulating the dynamic properties of the sword. In effect, I'm watching something different, than say Peter, but I'm getting similar results.

Can't mention this, without at least touching on "LPM" {buzz word Tink appropriated that describes a very "handy" sword}.Low Polar Moment can be done two ways, one by adding a lot of weight to the pommel, another doing a lot of taper in the blade, having a large part of the mass of the blade/tang close to the hand. On the surface, the high taper way looks superior, and in most cases this is the one I like best.......

However, I got to handle a couple of antiques where a heavy pommel was used to bring about the handling characteristics the maker or owner of the sword wanted.........

To make a long story short, many blades have two {or possibly more, I've yet to see more than two} "sweet spots" harmonically. With a given pommel weight, the primary handle node and the larger deminode will be about where I think its "nominal". By gradually adding weight, the primary handle node slides away from the cross, the demi eventually disapears. If you don't give up, you'll eventually reach a point where you have a new "node" at the cross, and what was the node is now a deminode........ and wonder of wonders, the dynamic properties which had become screwed during the weight additions is now good again, but quicker because the cog is back.........but there's a danger to this, see my aside on the nodes and blade bending.........This works very well with a very few blade types, won't work at all with some......and the character of distal taper choices is limited.

The best way to accomplish the 'low polar moment" in a sword, is start with thick stock, and concave distal taper, start tapering in a hurry, and gradual it out as you approach the tip. Depending on blade type this makes for not only a superb handling sword, but one which is very dynamic, will handle lighter than it is, and cut heavier than it is........There's some dangers in this too..........

Running out of time, but there's still ricassos and edge geometry...... edge geometry affects handling more than it affects nodes, but it does affect the dynamic handling of a blade..... ricassos affect the whole thing........

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PostPosted: Thu 19 Oct, 2006 1:22 am    Post subject:         Reply with quote

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 Wink Razz ?
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