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Larry Bohnham





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PostPosted: Thu 20 May, 2010 10:05 am    Post subject: Importance of point of balance         Reply with quote

I have read the articles on this site regarding blade geometry and design and would like a clarification as to how important the center of balance is when selecting a sword. Specifically, it seems that a PoB that is numerically greater, say 6 inches rather than 3 inches would indicate a blade that feels, and probably is, less point heavy because there is more of the mass of the hilt behind the PoB. Would this be correct? Further, would a PoB which is father toward the point be better or not for improving the speed and agility of a hand and a half type sword?
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Vincent Le Chevalier




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PostPosted: Thu 20 May, 2010 10:56 am    Post subject: Re: Importance of point of balance         Reply with quote

Hi Larry,

The consensus is that point of balance on its own does not mean much. It tells certain things, though, and I'll try to clarify.

Larry Bohnham wrote:
Specifically, it seems that a PoB that is numerically greater, say 6 inches rather than 3 inches would indicate a blade that feels, and probably is, less point heavy because there is more of the mass of the hilt behind the PoB.

Actually it's the opposite Happy
Think of it this way: the point of balance tells you where the mass of the sword is on average. The further it is from your hand, the heavier the sword will seem, as you can experience with a simple stick: it is more blade-heavy when you hold it at one extremity, than when you hold it closer to the middle.

The problem comes from the fact that we are sensitive to other things than the average location of the mass. The actual feeling of blade presence depends on other things that are not as easy to measure and not usually published, and that is still a work in progress as far as I'm concerned. But if you compare swords of a similar type the one with the CoG furthest from the cross will feel more blade heavy in general.

If the topic of sword balance is of interest to you, you've got many great discussions to read in the spotlight topics of this site (click on Dynamics, Properties, and Performance). I made a sort of literature review here as well...

Hope this helps,

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Nathan Gilleland





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PostPosted: Thu 20 May, 2010 11:04 am    Post subject:         Reply with quote

I am far from an expert, but a POB that is closer to the hilt would result in a "quicker" point. The further out on the blade the POB is, the heavier the tip of the sword will feel. If the POB is close to the hilt, this lets you know that more weight is in the hilt, allowing it to counterbalance the length and weight of the blade.

I see that Vincent explained what I was going to say very well. I can't say it any better than he has.

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Michael Edelson




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PostPosted: Thu 20 May, 2010 11:31 am    Post subject:         Reply with quote

I'm going to disagree with Vincent on the importance of PoB (or CoG, center of gravity, which I prefer). I own quite a number of swords, mostly reproductions, and I can sum up each of them, in terms of handling, with two bits of information: COG, and weight.

In fact given a specific type of sword (longsword, arming sword, etc.) and those two figures, I can predict how the sword will handle (as far as I'm concerned, it's accurate to me). My own swords behave in accordance with their types, weights and COGs.

To give a concrete example, before going to the New York Custom Knife show I looked at the statistics for the Albion Viceroy and got a feel for how the sword would handle. Then, at the show, I got to handle one, and it was exactly as predicted.

One thing that is not easy to predict is how a sword will feel in prolonged use, as in continuous practice, drills, etc.

One thing I find absolutely useless is the so called "pivot point" or point of rotation or whatever it is called. It tells me absolutely nothing.

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PostPosted: Thu 20 May, 2010 11:45 am    Post subject:         Reply with quote

Michael Edelson wrote:
One thing I find absolutely useless is the so called "pivot point" or point of rotation or whatever it is called. It tells me absolutely nothing.


My own experience is completely opposite of yours. One needs only handle the Albion Svante or the A&A German Bastard Sword to see an extreme case of how the pivot point is relevant to the conversation of dynamics. These swords have a pivot point nearly at the tip of the blade. Their handling characteristics are vastly different than many swords with essentially the same overall dimensions and point of balance measurements. In fact, I'd say they're downright shocking (in a good way).

For me, simply looking at measurements and, in particular, point of balance, does not tell me much about how the sword is going to feel when it is in motion.

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Walter S




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PostPosted: Thu 20 May, 2010 12:29 pm    Post subject:         Reply with quote

Generally sword dynamics range from cutting swords with point of balance far down the blade and a lot of bulk toward the tip (less agile, good for powerful cuts) to thrusting swords with point of balance near the hilt and not much bulk near the tip (more agile, good for accurate thrusts).

(Im not much of a sword expert, so I hope I didn't screw this up)
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Jared Smith




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PostPosted: Thu 20 May, 2010 1:57 pm    Post subject:         Reply with quote

Walter S wrote:
Generally sword dynamics range from cutting swords with point of balance far down the blade and a lot of bulk toward the tip (less agile, good for powerful cuts) to thrusting swords with point of balance near the hilt and not much bulk near the tip (more agile, good for accurate thrusts).

(Im not much of a sword expert, so I hope I didn't screw this up)


I think you did a good job of describing it really. A lot of terms "pivot point", "CoP" as a function of a vibratory node, etc., as used here are somewhat different from the definitions of a physicist or athletic equipment manufacturer. We have exhaustive older posts debating how to use them. As far as I know, no racket or bat industry has really perfected the task of assigning a "true pivot point" for purposes of CoP that accounts for individual styles and variable types of swings that use wrists and arms either. Point of balance is used appropriately though.

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Michael Edelson




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PostPosted: Thu 20 May, 2010 2:16 pm    Post subject:         Reply with quote

Nathan Robinson wrote:

For me, simply looking at measurements and, in particular, point of balance, does not tell me much about how the sword is going to feel when it is in motion.


I like to pick a different sword every now and then to do my daily drills, and I may do a thousand cuts with each sword in a given week. I've measured their pivot points several times using methods I don't even remember (except the silly waggle test), but at no time have these measurements given me any meaningful information whatsoever about how these swords handle.

However, weight and COG always convey clearly what I'm feeling when I train.

Now it could just be me. Happy

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Alen L




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PostPosted: Thu 20 May, 2010 2:19 pm    Post subject:         Reply with quote

let me put in my two cents as well, more in terms of what a PoB generally does when you use a sword.

As many people said, the larger the PoB is, the more point-heavy the sword will feel. What this means practically is that it's not as fast as a sword with a small PoB, and will throw you off your balance much quicker. This is not necessarily a bad thing, in fact, i would recommend it for beginners. It gives you a good feel of what your stance should be like, since if it's not good enough, a swing will throw you off-balance. It will also make you "feel" the point a lot more, which is very important, and you will automatically strike with point first, the body following it, and not the other way around. Also, the point will not dance as much when you strike (talking for beginners, of course), which also strengthens the correct strike mechanics.

If a PoB is smaller, that is closer to the guard, the sword will be much faster, nimbler, and more controllable, but also more difficult to use properly. This might seem like an oxymoron - it's more controllable, but more difficult to control. It is also quicker, and usually much more responsive.

So, if you're taking up swordfighting, i would recommend a more point-heavy sword, if not a sword with a smaller PoB. I find it quite useful, though, to do a few swings with the sword i started out with, just to check how much i can control it.

regards!
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Thom R.




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PostPosted: Thu 20 May, 2010 2:21 pm    Post subject:         Reply with quote

Michael Edelson wrote:

One thing I find absolutely useless is the so called "pivot point" or point of rotation or whatever it is called. It tells me absolutely nothing.


I am afraid I am going to have to disagree with you on that one point. If we got together with your A&A German Rapier and me with my A&A Cavalier rapier you would immediately pick up on the difference that the two swords have in terms of Pivot Point. The COG tells you where the center of mass is - but it tells you absolutely nothing about the distribution of mass on either side of that point.

A good example would be a single hand vs a hand and a half sword. You can have a short hilted single hand sword with the exact same weight, blade length, and COG placement on the blade as a hand and a half sword yet the swords will feel very different because the distribution of mass is different. Especially when the sword is placed into motion and a moment force is developed behind the hand at the pommel which you must control to keep the blade aligned.

edit since we were typing at the same time: Michael I have no doubt given your experience that for simple cross hilted western swords, you can look at the general size, weight and COG and have a pretty darn good idea how the sword will handle. I feel like I can gauge 80% of a sword's handling character by looking at just those numbers too. But........ that doesn't mean PP's don't matter or that distribution of mass does not matter. It still does, especially for complex hilted swords.
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Michael Edelson




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PostPosted: Thu 20 May, 2010 2:31 pm    Post subject:         Reply with quote

Thom R. wrote:
I am afraid I am going to have to disagree with you on that one point.


You can try, but you'll always be wrong. You see, you can't disagree with the fact that *I* find something useless. I am the final arbiter of such matters. Happy

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Michael Edelson




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PostPosted: Thu 20 May, 2010 3:07 pm    Post subject:         Reply with quote

Sorry, couldn't help myself. Happy

I've handled the Cavalier rapeir (I think...maybe it was one of the similar looking ones A&A makes), and to me the difference between the two is summed up nicely by weight and COG.

However, those are rapiers, and I'm not a rapierist. Also, I evaluate single hand swords differently from longswords, so to me, differences such as those you describe are already accounted for by sword type.

This may not be a very scientific system, but it doesn't have to be, it just has to work for me. People often ask me which longsword I recommend for their studies, how it would handle, etc. Or they tell me how they want a sword to handle, and I recommend one for them. So far I've been accurate in matching people's needs and wants to the right sword, so I must be doing something right. Happy That doesn't mean pivot points are useless, it just means that thus far, they are useless to me.

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Timo Nieminen




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PostPosted: Thu 20 May, 2010 3:58 pm    Post subject:         Reply with quote

3 numbers will do:

1) Centre of mass a.k.a. centre of gravity a.k.a. point of balance
2) Mass a.k.a. weight
3) Moment of inertia, which is the rotational inertia, which says how much torque is needed to get any given rotational acceleration. (Some fields of engineering call something very different a "moment of inertia"; the one meant here is the standard meaning in rotational dynamics.)

For handling involving rotation of the sword, you want to know the moment of inertia about the point that the sword rotates about. If the hand is stationary, this point is on the grip. Conventionally, moments of inertia are given about the centre of mass, but this is easily converted to MoI about any other point given the location of centre of mass and the mass.

All three matter. 3) MoI is very important, and is why distal and profile taper are important. If it didn't matter, a sharpened uniform bar with an appropriate pommel would be a well-handling sword.

"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.
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Dustin R. Reagan





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PostPosted: Thu 20 May, 2010 4:00 pm    Post subject:         Reply with quote

Thom R. wrote:

You can have a short hilted single hand sword with the exact same weight, blade length, and COG placement on the blade as a hand and a half sword yet the swords will feel very different because the distribution of mass is different.


I'm not Michael, but i think he covered this here:

Michael Edelson wrote:

In fact given a specific type of sword (longsword, arming sword, etc.) and those two figures, I can predict how the sword will handle (as far as I'm concerned, it's accurate to me).
(emphasis mine)

For what it's worth, my experience mirrors Michael's.

Dustin
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Michael Edelson




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PostPosted: Thu 20 May, 2010 4:12 pm    Post subject:         Reply with quote

Timo Nieminen wrote:

All three matter. 3) MoI is very important, and is why distal and profile taper are important. If it didn't matter, a sharpened uniform bar with an appropriate pommel would be a well-handling sword.


Such a bar would have a COG about15" or more from the cross and weigh about 5-6lbs. If given a sword with the following specs:

Type: longsword
LOA: 46"
Blade length: 36"
COG: 15"
Weight: 6lbs

I would tell you....wait for it...."it handles like a crowbar." Happy

No need for a pivot point or a MoI.

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Harry J. Fletcher




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PostPosted: Thu 20 May, 2010 4:53 pm    Post subject: Purpose of The Blade         Reply with quote

As most of you know I have long been an advocate of the proposition that early medieval swords were more for percussive use and as such would have been slightly blade heavy. Early viking swords and some German swords bear out this blade heaviness hypothesis. A blade heavy sword aids in cutting much as a cleaver blade does and hence its percussive ability. the PoB would be very close to the PoP which is to say very much toward the end of the blade. considerable strain is placed upon the wrist with these swords. This is not true of all swords or even of a great many swords.

A sword for hand use with a PoB close to the cross has a good balance and agility. One must remember that in the early medeival period that the thrust was not used but the slash and smash of the sword. Thus one must not think of the Viking or Norman sword as rapier type weapon but as one where the wrist could develop better control of the blade to direct it along with the arm to the point one wished to deliver a blow. The PoB would most likely be around 3 inches from the cross.

Swords are of different types and periods and of different tastes but I think that when armor got better and other weapons developed for use or were used such as the war hammer, poleax, morning star (ball and chain) Swords of war (two handed swords, Bastard swords ( one and one half hand swords) were all mixed up and there was no quick delineation between the two but one purpose was paramount...to give more power to the cut! Apparently this was originally a German innovation and spread to the rest of Europe and England. As to the point of balance I would hazard a guess that most of these swords would have had a PoB of about 6 to 8 inches from the cross to keep the sword blade heavy for the cut and slash. These varied somewhat and there was no hard and fast rule as differences between smiths of one region and another as well as personal prerequisites of the end user would have some impact.

In reference to an earlier post it goes back to the stick analogy. If you want a more agile sword the PoB is closer to the cross and this tends to be the case in single hand wielded swords. In longer blades such as two hand swords of war the PoB would more likely be further from the cross.

Now that I have made this clear as mud, I know that I am going to be attacked for my percussion use of the sword hypothesis and simplified analysis of the PoB.

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Timo Nieminen




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PostPosted: Thu 20 May, 2010 5:15 pm    Post subject:         Reply with quote

Michael Edelson wrote:
Timo Nieminen wrote:

All three matter. 3) MoI is very important, and is why distal and profile taper are important. If it didn't matter, a sharpened uniform bar with an appropriate pommel would be a well-handling sword.


Such a bar would have a COG about15" or more from the cross and weigh about 5-6lbs.


If it would weigh 5-6 lbs, use a thinner bar. If the COG would be 15" or more from the cross, then you and I must have a very different idea of "appropriate" pommel.

Michael Edelson wrote:

If given a sword with the following specs:

Type: longsword
LOA: 46"
Blade length: 36"
COG: 15"
Weight: 6lbs

I would tell you....wait for it...."it handles like a crowbar." :)


Try it sensibly, rather than with a ridiculous choice of weight.

Choose a bar and pommel so that the total lengths are as above, COG 4", weight 3lbs. This is possible; you can really do this and try it for yourself. Will it handle like a well-balanced sword?

You can be even more extreme. Get the lightest bar you can, and add weight to the tip and pommel until it's the weight of a sword, with the CoM where you want it. Will it handle like like a well-balanced sword?

Are you really trying to say that mass distribution along the blade doesn't matter beyond getting the CoM in the "right" place?

Michael Edelson wrote:
No need for a pivot point or a MoI.


Given a well-balanced sword, you will know, well enough, given the mass and CoM, what the MoI is. This is why it's a well-balanced sword. Given the mass and CoM, and no further information beyond "sword" and length, you don't know.

Easy enough to find the location of the CoP (rotational dynamics version), which can be done by the useless waggle test, or the equivalent pendulum test. That, the mass, and a tape measure, gives you the MoI if you want a number. The CoP and the other figures are enough for comparison.

A quick check finds that the CoP of an Albion Ringeck is just short of the tip, the CoP of a Cold Steel H&H waster is about 1/3 up the blade from the tip, a red oak bokken about 1/2 way up. I know which one is well-balanced, and I notice a correlation between the CoP and "goodness".

"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.
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Larry Bohnham





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PostPosted: Thu 20 May, 2010 6:48 pm    Post subject: Importance of point of balance         Reply with quote

Thanks to all of you for your input.
Sounds to me like predicting the handling qualities of a sword is very similar to predicting the qualities of a race car or airplane. One can get a general idea from the numerical design specs of how it will handle, but there are always the intangibles that make something work well for one person, but less well for another. Thanks for setting me straight on how to interpret sword specs, it will be helpful going forward in my search for hand-and-a-half sword that I will like.

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a furore Normannorum libera nos Domine

"Henry, get down off that horse with that sword, you'll put someone's eye out!" Mrs. Bolingbroke's advice to her son, Henry, on the eve of the battle of Agincourt
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PostPosted: Thu 20 May, 2010 8:28 pm    Post subject: Re: Purpose of The Blade         Reply with quote

Harry J. Fletcher wrote:
As most of you know I have long been an advocate of the proposition that early medieval swords were more for percussive use and as such would have been slightly blade heavy. Early viking swords and some German swords bear out this blade heaviness hypothesis.


But what about the hundreds of surviving early medieval swords that contradict this? Happy

But back to the main point: No single measurement, by itself, is a good indicator of how a sword handles, and even two or three don't give a full picture. Craig Johnson once used a good graphic to describe how POB alone is useless, and I wish I knew where to find it. I'll try to describe it. The first picture had a shape that was very thin in the middle and very wide at the ends (kind of like barbells), and the second shape was very wide in the middle and very thin on the ends. Both weighed the same amount, and both had the exact same point of balance... yet you could see that obviously neither would handle the same at all.

This is why its important to use the numbers as a general guideline, but not as concrete evidence for how a sword will handle. I prefer to read people's general impression alongside the numbers to get a much more rounded view (and even this obviously has big limitations).

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Jean Thibodeau




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PostPosted: Thu 20 May, 2010 8:54 pm    Post subject:         Reply with quote

Past the numbers the feel in hand tells an experienced swordsman how the sword will perform for him and if it's a well balanced sword for it's type and the type of techniques adapted to the type.

One would judge a single hander, a rapier, a twohander, a 19th century sabre as good or bad within it's type and not using the criteria for a different type.

Personal preference i.e. subjective like or dislike would vary according to experience and habit ! At times one can hate a sword's handling but after getting used to it or learning techniques better adapted to it's nature one can learn to like a sword one first hated.

There is a wide spectrum of good swords that handle very differently but there is also lots of potential " lemons " modern or period swords.

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