Info Favorites Register Log in
myArmoury.com Discussion Forums

Forum index Memberlist Usergroups Spotlight Topics Search


Please help our efforts with a donation. This site requires ongoing funding and your donations are crucial to our future.
Last 10 Donors: Neil Eddiford, Chad Arnow, Jean Thibodeau, Robert Morgan, Adam Rose, Jerry Otahal, Michael P. Smith, Mikko Kuusirati, Eric Bergeron, Daniel Staberg (View All Donors)

Forum Index > Off-topic Talk > Use of the term CoP and controversy Reply to topic
This is a Spotlight Topic Go to page Previous  1, 2 
Author Message
Peter Johnsson
Industry Professional



Location: Storvreta, Sweden
Joined: 27 Aug 2003
Reading list: 1 book

Spotlight topics: 3
Posts: 1,757

PostPosted: Sat 10 Jun, 2006 2:03 am    Post subject:         Reply with quote

Handling, function and performance in a sword depends on many factors.
Very few of these factors act independently.

Vibration nodes and their placing have an effect on stiffness and vibration dampening.

Placing of pivot points is an effect of the dynamic balance of a sword (the way the sword behaves while in motion). The pivot points also play a role in shock dampening.

Normally when you take measurements on a sword you use the guard (or the shoulders of the blade) as 0: it is a good and handy neutral.

Terms like pivot points and vibration nodes (or even harmonc balance or dynamic balance) can be helpful in that they define some certain aspects of the functional properties of a sword. Unfortuantely, they can also be used in a way that is misleading and confusing when not applied correctly or too broadly. Having defined aspecs might make it seem that we have all the important facts laid out before us. If we only put the correct data in these specific values, we get a superior sword...

In reality, swords are complex. No single statistic or limited set of statistics will really tell you all you need to know to get a complete picture.
You can get some kind of impression however, and that is why makers provide a basic set of stats for customers to get a general idea of the characteristics. Personally I think a short description of type and character (without numbers and measurements) is more valuable. When you read Oakeshotts work you see how he excells at this: he manages to describe swords types and their development with very littel numenrical information. I think he was well aware that many of the important things are not really measurable.
When documenting swords I note physical dimensions such as lengths, widths and thicknesses of different parts, shapes of cross sections and volumes, mass and point of balance, placing of vibration nodes in grip and blade and correlation between pivot points in grip and blade. These are the most important points of reference. *Together* they provide a "profile" or functional ID of a sword. They act as a reference to the memory of the feel of the sword together with drawings and photos. No stat or detail alone will tell you much. It is all in the combination of features and characteristics: the proportion, ratio and relation between the spesifics.
Still I value most a personal impression of a weapon. I will never attempt to make a true copy or reconstruction of a sword if I have not held it in my own hands and spent some time with it. A list of numbers can never replace that.

The fact that you can measure certain aspects of a sword is helpful. Still, it is what is *between and behind* those numbers that really matters.
View user's profile Send private message Visit poster's website
Vincent Le Chevalier




Location: Paris, France
Joined: 07 Dec 2005
Reading list: 15 books

Spotlight topics: 1
Posts: 844

PostPosted: Sat 10 Jun, 2006 3:02 am    Post subject: Re: Web of complexity         Reply with quote

Craig Johnson wrote:

Vincents comments are very good and I have looked at many of these same issues in depth as well. A few years ago Gus, Tinker, Peter, Jason, and myself spent an evening discussing the varying virtues of these elements and the possibilities of what could or could not be codified and measured and end up being meaningful.
[...]
From that time on I have had several discussions with these guys on an individual basis and the interesting thing is we all still find elements we had not though of as yet and find examples that challenge our perceived understanding of the whole what makes a good sword question.


Now, that's a discussion I would have enjoyed Happy
I'm basically trying my best at confronting my theories with various types of weapons as well, but my collection is somewhat lacking in the area of quality swords, so I really appreciate all the comments here...

Craig Johnson wrote:

When we look at the pivot point discussions I agree that they are strong factors in the equation but I am often dissatisfied with the moving stick model or even the simple sword arc model. It seems to me that the sword, as any tool used for striking, adjusts its function when the hand is applied to the tool and it is not just the hand. When one starts to model a sword in motion is quickly becomes apparent that the style of grip, wrist/elbow/shoulder/waist action all impart factors that are not insignificant to the swords action and resulting numbers as far as what really happens in a sword cut in air or against a target.


I fully agree that the moves and efficiency of a weapon depend hugely on the person holding it, more than on the properties of the weapon maybe... That is why I recently largely dropped my tries at calculating impacts. Much too dependent on many aspects having nothing to do with the sword as a physical device. I don't feel the urge to develop that further than what I exposed earlier here, because if it gets too complex it becomes useless as a way to define clear properties in reviews, for example.

Craig Johnson wrote:

As I thought more about this I started to feel that there is another dimension to this all. It is what I call the rotational point of the sword. This is the point on the blade that the sword wants to move around as you manipulate the sword in action. This is what I guess you might call the "active center of gravity" for want of a better term. (if anyone has one please suggest it) This will change per user and as different parts of the swing are emphasized or concentrated on i.e. grip, wrist, elbow, shoulder, waist. Now, to my mind, this has more to do with how the sword works in combat than some of the other factors, as the relationship of two three dimensional objects moving around each other in space is what combat comes down to and the function of a sword is to work in that environment with a certain degree of success. The result of how that sword interacts with the other sword/target is what it was designed for and very difficult to apply measurable numbers to. ( let me know what you think of the above as it is more an amorphous idea in the subconscious than a fully blown active theory)


That's more or less what I was thinking about as well. Though I don't like the idea of being so much related to the user. In an ideal world (somewhat utopic, but hey, one must have goals Wink ) what I would like is this : a few numbers, being only dependent on the weapon's mass distribution and geometry of grip (obviously the balance is not the same when you hold the thing at different places), to which each individual can relate, because he knows what range of those numbers feel right for him, or what range of those numbers are historical, etc... I really feel I'm getting close to that (see below), and I will probably sollicitate myArmoury's collectors for further confrontation with the "real world" very soon Happy
Of course that will not tell the whole story about the sword. The aim would be to have something at least complete in a solid dynamic sense, thus my ideas on pivot points.

During this writing, I realize that Peter Johnson has just made a very interesting post about that... I agree with him in that, not being a sword maker, I'm not trying to reproduce something based on the numbers. I realize that it would be difficult if not hopeless. I'm speaking more from a user/buyer point of view, who needs to have an idea, at times without having a chance of touching the sword...

The only thing I disagree with is that I like better to take the Center of Balance as a reference in my reflexions, but that's purely technical, as it eases the exploration of the variations of caracteristics when hands move (on an axe for example). If we limit ourselves to swords, I guess the cross is indeed a more natural reference.

Marton Pap wrote:

(It would be exciting if the swords have the same overall taper, and even more if they don't have the same but could be categorized into two or three families.)


As it happens... I thin I'm nearly achieving that last part at the moment. Basically, I've been measuring the pivot points, hands position, center of balance of most anything I came across that can qualify as a weapon (from iaitos and bokens, to wooden swords, my two quality swords of course, dagger, stick, foil, a bo grabbed with different methods, and even a decorative axe build in the poorest way you can think of Wink ). I used this sample (representative of not much, but with huge variability in handling) to test my definitions of properties. Just today, I used a set wich seems to be able to discriminate quite nicely between the weapons, forming groups that I consider representative of what I feel in handling. I still have to further polish the physical justification for all that, so I'll refrain from starting explanations. But I feel it's close, real close...

Joel Whitmore wrote:

When you move into two-handed swords the blade vibration does affect handling.


I admit I have never handled such weapons, so I take your word for this. Does it affect moving from guard to guard as well, or just cutting motions ?

Jared Smith wrote:

A 2- 5% difference may be a life and death issue over the course of a few hundred swings with unimaginable fatigue progressing throughout such a day of battle.


In fact I'm not even sure of that. From my practice of kenjutsu, it seemed to me that the overall moving, acceleration of the weapon, sidestepping, change of guards, control blade on blade, is more tiresome than the actual cutting (that is, when the weapon is in the target) wich is but a split-second of the fight. But then obviously I've never been in a fight where real cutting was involved, and I sure hope it will go on like this, by the way Wink

Chad Arnow wrote:

It's just one stat of many. How it mates up with pivot points and how a sword's overall mass is distributed is much more important. While it is relevant, I wouldn't try to make too much out of it.

It's a static measurement that shows a region on the blade where many cuts will be effective. How well the sword moves is determined by balance, weight, and mass distribution more than CoP.


OK, so you just summed-up a good deal of my lengthy posts in four lines here Big Grin Just to say that I'm fully with you on that...

Too bad I'm away from Internet this week-end, please people keep up discussing this, I enjoy the reading Happy

--
Vincent
Ensis Sub Caelo
View user's profile Send private message Visit poster's website
Nathan Robinson
myArmoury Admin


myArmoury Admin

PostPosted: Sat 10 Jun, 2006 3:10 am    Post subject:         Reply with quote


This topic has been promoted into a Spotlight Topic.

.:. Visit my Collection Gallery :: View my Reading List :: View my Wish List :: See Pages I Like :: Find me on Facebook .:.
View user's profile Send private message Send e-mail Visit poster's website
Angus Trim




Location: Seattle area
Joined: 26 Aug 2003

Spotlight topics: 1
Posts: 870

PostPosted: Sat 10 Jun, 2006 11:19 am    Post subject:         Reply with quote

Since this thread has varied a great deal from the original topic, I thought I'd add more to this.........

We've kind of concentrated on the blade, which is easy to do, because its the most important part of the sword. But the ergonamic parts of the blade are important too..... How the operator of the sword's hand works with the handle, relates to guard and pommel will be a part of the handling and striking equation. How a hand interacts with the grip can make or break the relationship of sword and swordsman.........

Also, back to the blade.......... everything is interconnected. You cannot over concentrate on the pivot points, as moving them will effect the nodes. Over doing the handle nodes, for instance, can and will effect the pivot points......Etc and so on.

After a while, things become just as subjective for maker as for the swordsman. Most sword handlers just want the sword to do the things they think a sword should. They want it to handle well, cut well etc....... If they are studying a certain art, Fiore longsword for instance, they want the sword to complement what they're doing.......... If the sword does that, and does it well, alls well with the swordsman's world........

A swordmaker eventually can "feel" whether a sword is "there" harmonically and dynamically, by just doing a few drills. Don't really need to slap the blade anymore, or measure pivot points. Does the sword track right? Does it follow the point naturally in a curving thrust? Or does it over or under steer? How does it react to the swordsman's footwork and technique?

Then we have to deal with the sword's design criteria and intended function. There was a lot of diversity during the medieval period, and a fifteenth century longsword intended for unarmored longsword work is going to be much difference in appearance, handling, function than an early 14th century warsword.............

As westerners, we quite often over analyze things, and miss the whole....... Does the sword do what it should? Or doesn't it?

Things like cop are important, but two different people can measure the same sword, and come up with a different measurement, by as much as three inches on a 35 inch blade........ So, most experienced people don't concern themselves so much with dry statistics..... what does the sword actually do?

swords are fun
View user's profile Send private message
Jared Smith




Location: Tennessee
Joined: 10 Feb 2005
Likes: 1 page

Spotlight topics: 3
Posts: 1,532

PostPosted: Sat 10 Jun, 2006 11:34 am    Post subject:         Reply with quote

The review of the Albion Landgraf and Sempach might reinforce your very accurate point Angus.
http://www.myArmoury.com/review_alb_lansem.html

Changes in grips (riser, shape, etc.) or pommels and guards have a signficant influence on the human factors that affect our perceptions of handlng even when the blade is the same blade. It is intriguing to see to models with very close statistics and the same blade design receieve recognition of very different handling traits / preferrences in a review like that.

Absence of evidence is not necessarily evidence of absence!
View user's profile Send private message
Joel Whitmore




Location: Simmesport, LA
Joined: 25 Aug 2003

Posts: 342

PostPosted: Sat 10 Jun, 2006 1:11 pm    Post subject: Angus I think you nailed it here!         Reply with quote

To me this topic has gotten way "over complicated". While the dynamics and engineering of sword blades is interesting, I liken it to a car. Many of today's modern cars are engineering marvels and I appreciate the work that goes into it and how all the pieces are integrated. However, as long as it performs the way I need it to, all that is relatively unimportant. If I buy a Type XII sword I know I am getting what is primarily a cutter adn I shold know about where I would get optimum cuts on that blade type. Thus would talk to whomever the manufacturer is and ask them where that "sweet spot" lies. If I decide to buy the sword, then when it arrives I can give the blade a whack and reasonably know where that first node is on the blade. No need to realy on a quantified definition of what the COP is. As Gus stated, the COP (whatever that is) is not the only thing that makes a great sword. I haev seen swords where the COP is in the proper place ( for its type) and th thing literally jumps out of your hand when you strike from vibrations to the handle. So this thread in a way frustrates me as well as fascinates me. People like Gus, Albion, Peter J and others survive in this niche business because they consistantly turn out quality products that react as we expect ( sometimes beyond what we expect ).

While I believe that an engineering paper on the mechanical and dynamic properties of a sword would be extremely interesting ( and probably overdue), all we seem to be doing here is covering the same ground with teh same questions. I am not trying to be negative, but there are far more aspects to sword design than COP and all of them are probably so interrelated that you cannot discuss one without the others.

To answer Vincent's question about big two-handers, it is possible to get the balde to wobble when moving from guard to guard. To be honest, this doesn't affect you all that much when the blade is properly balanced. I cannot say what sparring is like with one of these blades when you start parrying with another sword; something I have not done. I do know that to get good cuts and edge alignment you have to be precise with your technique. However, I would venture to say that even a misaligned cut with a blade of this size would be traumaticfor your opponent!

Joel Whitmore
View user's profile Send private message Send e-mail Yahoo Messenger
Jared Smith




Location: Tennessee
Joined: 10 Feb 2005
Likes: 1 page

Spotlight topics: 3
Posts: 1,532

PostPosted: Sat 10 Jun, 2006 8:02 pm    Post subject:         Reply with quote

Aspects of sword handling are very complicated. Believe it or not, so is the way a golf ball behaves when struck. In the context of sword reviews “CoP” seems to convey a much more complicated and integrated set of performance aspects of swords than the simple physics definition of Center of Percussion (CoP.)

There are some personal interpretations I have gained more confidence in from this post with respect to typical broad swords.

• The location typically described as “CoP” in sword reviews is an “approximately optimum” place for a sword edge to make contact when striking as if the reviewers intended to cut. It is analogous to the term “sweet spot” often used when technical industries discuss some types of athletic equipment. The pivot point corresponding to this “CoP” might occur at some non intuitive locations (such as completely beyond the sword pommel, out in the air somewhere…)
• The better manufacturer’s and reviewers are doing their best to identify this optimum impact location based on experience and actual trial usage which factors in “ergonomic aspects” and all of the complex interactions from grip, pommel, guard, etc. It is not just arbitrarily calculated based on some assumed pivot point and the mass distribution of the sword.
• It has been asserted that for swords “CoP” is universally specified in terms of a distance out in front of the guard, even if not every one states this. This might be the most useful aspect of the statistic (have not quite made up my mind) since it indicates about how far from an opponent the wielder should probably be when striking to cut.
• With good design practices resulting vibrations and harmonics are tuned to be dampened in the grip area and blade “CoP” area when impacts occur near this “CoP.” Sword strength/ durability should also accommodate impacts at this CoP location. However, these complex aspects of the design are not guaranteed to be optimized at the “CoP” for every sword you might come across. I personally value these aspects of the design greatly, but would exclude them from definitions of CoP.

Absence of evidence is not necessarily evidence of absence!
View user's profile Send private message
Vincent Le Chevalier




Location: Paris, France
Joined: 07 Dec 2005
Reading list: 15 books

Spotlight topics: 1
Posts: 844

PostPosted: Sun 11 Jun, 2006 10:45 pm    Post subject:         Reply with quote

Angus,

I'm quite with you on the ergonomy issue. That's a completely different problem, having almost nothing to do, I believe, with the physics of handling, and all to do with the shape and materials of the handle, even heavily dependant on the particular physionomy of your hand... Not something I would try to put into numbers, for sure. It has to be experienced first-hand, even a review is not terribly helpful here since your tastes and morphology can significantly differ from those of the reviewer.

On the review of the two Albion swords cited by Jared, I'd like to point out that though the blade is the same, the change of grip does not just have an effect on ergonomy, it also affects the balance. According to the review, the location of the POB was shifted by 3/4in, which I consider big enough. Indeed the effect on pivot points must be even greater, and that could explain to some extent the variation in handling.

I agree with you and Joel as well about the fact that appreciating a sword when in your hand does not have to rely on statistics either. When you are experienced enough with the kind of sword you are interested in, you don't need statistics, as long as you can lay your hands on the weapon. And indeed it is very simple, that's what I felt several times as well.

However, the weapon is not always at hand, and there are virtues I can see in calculating numerical properties.

It allows to remotely appreciate a sword, at least, some properties of it, which is better than nothing. It's complimentary to a reviewer's opinion in this respect, since you can directly compare it to things you know, whereas a reviewer probably has had different experiences than yours. It allows you, in a way, to confirm and weight the opinion of the reviewer. Imagine what someone proficient only in sport fencing would write about a type XI sword, even one very well done. He could be saying in his review that the balance is horrible... But if you are able to compare numerical figures with others you know, you can adjust the appreciation of the balance and conclude that after all this seems right. It does not invalidate the review, which still could contain useful information about materials, assembly, decoration, whatever... The numbers give you a reference point. OK, that's a rather extreme example, but I hope you get my point here. Something similar probably does happen in real life, to a more limited extent.

Numbers act as common references, allowing comparison without physical contacts. Comparing swords in museums comes to mind in this respect. Having some carefully chosen, representative numbers could prove immensely useful to an inexperienced newcomer, in my opinion. Now, the question of what those numbers should be is truly difficult... A question I will not try to answer here, since it's way off-topic and would necessitate a detailed explanation.

The starting point of the thread was the relative uncertainty about the definition of the COP. I don't think that it's a good idea to consider that there are many elements, subjective such as comfort, mixed in a number. In the end it amounts to say that somehow we are giving a "grade", and not measuring something. In that case I would trust more the ability of the reviewer to express his opinion in words, with nuance and compromises, rather than a mono-dimensionnal number that cannot reflect the various trade-offs that have to be made to obtain a good sword. But then that's just my point of view as a sword buyer/user...

Well, informative discussion anyway. I hope those matters will continue to be discussed in the future...

Regards

--
Vincent
Ensis Sub Caelo
View user's profile Send private message Visit poster's website


Display posts from previous:   
Forum Index > Off-topic Talk > Use of the term CoP and controversy
Page 2 of 2 Reply to topic
Go to page Previous  1, 2 All times are GMT - 8 Hours

View previous topic :: View next topic
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum






All contents © Copyright 2003-2019 myArmoury.com — All rights reserved
Discussion forums powered by phpBB © The phpBB Group
Switch to the Basic Low-bandwidth Version of the forum