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Thom R.




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PostPosted: Tue 05 Aug, 2008 1:45 pm    Post subject: Sword Mass Index         Reply with quote

I guess its time to share the following, although I am a bit reluctant to do it, but I have run it by a few swordsmiths who have encouraged me to post this here. Note however, disclaimer: its a work in progress.

Over the years I have been a bit frustrated by an inability to adequately describe swords in terms of their feel and handling characteristics, even to other knowledgeable folks who have a fair experience with blades in the hand. We (including myself) often revert to describing our swords like we do wines, using such terms as "light and lively" or "hits with authority", or "flows easily" etc etc.

Hence, I have been on a Arthurian quest (probably hopeless) for a better method to quickly and adequately classify or describe swords based on measureable characteristics. Now, I do understand that in the end this approach has its limits as so many variables can affect the handling of a sword. But a lot of things in life are complex, that doesn't mean (to me anyway) that we shouldn't try to improve our understanding, even if it is just a tiny step forward. So please take this posting in that spirit..........

I have struggled with various numbers and ratios involving everything from lengths to POBs to weights to tapers and so on and so forth. I have written computer programs, looked at pivot points you name it, I am an engineer so I have done it. But because I can't go to every blade show and I don't live anywhere near Seattle, Minneapolis, or New Glarus,what I really was hoping for was not a global system of categorization, but something that would allow me to readily get a feel for a sword based on readily available measurements, particularly for comparing a sword against its peers, i.e. swords of a similar type and size.

At the end of the day after crunching a lot of numbers and a lot of ratios and doing a lot of correlations back and forth, this way, that way, upside down, inverted (when all else fails invert, always invert), and turned around, having handled 20+ swords in the production market the past 4,5 years, I found myself back at the beginning (isn't that often the way, no matter where you go there you are) and finally decided that KISS was the best approach so I began tabulating a simple ratio of a sword's total weight to its total length (in grams and cm). I call this simple ratio the Sword's Mass Index. Yes I know that sounds stupidly simple, but when charted against the swords total weight, you do get this general pattern in which you can assess where a particular sword falls, and you now have a benchmark number that you can use to compare two swords of similar type.

Now before I go any further, I just want to define a few things. First, a single hand sword in my book is simply that, a sword with a hilt of 18 cm or less which has room for really only one hand. Once you get above that, now you are in hand and a half or two hand territory as to really be able to put two hands on the sword generally requires 22 cm or more. Most hand and a half bastard swords have tangs that are 24 cm or longer. Second, I am a relatively big guy, but for me, a sword needs to be under 1300 grams in weight to be a single hand sword. Above that, its pretty hard to work the sword accurately with one hand let alone wield it for any length of time. And if you study swords you see that historically, most single hand swords are less than 1300g. Now, as for the breakpoint between bastard swords and true two handers, that is a bit subjective as well, but for me, once the weight gets above about 1550g, generally I find that I need two hands on the sword at all times. This will vary by person. Hand a half swords, meanwhile can be wielded in one hand or two because of their longer hilt/tang lengths, and their relatively light weight. In addition, for me there is also this grey zone (which I call for lack of a better term 1.75 hands) where the boundary between a two hand sword and a hand a half sword gets a little fuzzy, that is swords weighing 1350-1550 grams, with a mass index above 12.

So without further rambling, here is a chart of the MI for a bunch of readily available swords, many of which have been discussed here or have been reviewed here, from Gus Trim, Arms and Armour, Albion, Del Tin and a few others:



What you see on my chart above are swords classified into single hand swords by virtue of their hilt/tang length, swords that are two hand swords because of their weight, and swords that are hand and a half swords because they are light enough to be wielded with one hand but are long enough to be held with two hands.

Just to orient things a bit - the sword on the lowermost left is the Albion Kern at 865 grams, and in the upper right that is the A&A German Bastard Sword weighing in at 2010 grams:



Now, remember, in the chart the variables are correlated, that is, weight of the sword is part of the mass index so you would expect to see a general trend in a chart like this, but what it does show is that despite all of the different sword types, there still are general trends across the chart, that is, there is an inherent "zone" in which good functional swords tend to fall into when it comes to weight and length irrespective of blade cross sections and types, and despite the autocorrelation there is still a fair amount of variability across the chart due to factors such as blade geometry (size, cross section and tapers), tang size, and hilting components. But generally, in my experience, I think I am willing, albeit with some reluctance, to state the following:

Most other things being equal (blade type, blade size), swords with a lower MI tend to feel more "lively", and are easier to control at full speed than swords that are higher in MI

Again, most things being equal, swords with a higher MI tend to strike harder and are usually more forgiving when cutting, and are less fussy about edge alignment than peers with a lower MI.

Although it depends to great extent on the POB, for swords with similar MI, even just a slight increase in total weight (30-60 grams) can have a drastic effect on the way the swords "feel". (this is why re-hilting a sword with new components can make or break a sword's handling characteristics sometimes)

Most of the bastard swords I personally prefer, despite having different blade types and lengths, tend to fall into a specific region on this chart. Which is why if nothing else, I have found this chart useful. It tells me if a sword is in my ballpark or not.

I believe that when it comes to two hand swords, there is, for lack of a better term, what I call a "central tendency" line along which swords that feel completely balanced in my two hands tend to fall on, e.g. Brescia Spadona, Svante, GBS. Even at its high weight the GBS feels not much heavier to me than the Svante.......I believe that is because the additional weight of the sword is appropriately balanced for its size and weight

But back to basics. The MI is really not that meaningful when comparing across sword types. But here is an example which I found useful for comparing Type XVIIIa swords



You can see how the four swords compare. The Munich and Del Tin 5157 have a slightly longer blades but the other three all have 36-36.5 inch blades. Yet because of the blade geometry and tapers and hilt lengths, the swords do have a bit of variability in how they feel and I think the MI clearly shows the trend between the swords. What this does is place eth swords into a context, although it is only the first step in their evaluation

I could go on to talk about complex hilted swords and why they tend to fall on the chart where they do as well as why swords like the big wide Type XIVs fall where they do, but I have typed enough for now.

To wrap up, as usual your mileage may vary, and all comments are welcome including "Thom thats the stupidest thing I have ever seen on myArmoury". tr
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Mike Arledge




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PostPosted: Tue 05 Aug, 2008 1:57 pm    Post subject:         Reply with quote

thanks for taking the time to put all of this together, pretty interesting info.
Mike J Arledge

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Gabriel Lebec
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PostPosted: Tue 05 Aug, 2008 2:16 pm    Post subject:         Reply with quote

Thanks Thom! Objective analysis is always appreciated. I am currently reading Tufte's The Visual Display of Quantitative Information, which is fun (although not as brilliant as Amazon reviews would have one believe), and your post has sparked a couple of ideas for me try some time.

I was particularly interested in where the Munich fell on your particular graphs, as I recently ordered one. It would be fun to expand this graph to include even more swords, although its value obviously rests heavily with linking the plotted relationship to personal experience and "feel."

Just curious: why were several swords omitted between graphs 1 and 2?

"The most beautiful experience we can have is the mysterious. It is the fundamental emotion that stands at the cradle of true art and true science." - Albert Einstein
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Thom R.




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PostPosted: Tue 05 Aug, 2008 2:52 pm    Post subject:         Reply with quote

Yes I have all of Tufte's books and did his one-day seminar a couple of years ago..... and have that chart of Napoleon's march to/from Moscow on my office wall! Excellent books. Sorry about multiple jpegs, various iterations. Its so stupidly simple that anyone can get and run the numbers but thats part of the reason I think it is useful as well (within limits of course)

the feedback/criticism i have gotten so far is that

1. POB is implicitly, not explicitly considered. that is, POB is affected by tang length and tang weight to a great extent ,which is factored in via using the total length in the MI, however, other things - particularly the distal and profile tapers are a big control on POB. and POB is one of the more important things controlling how a sword feels in the hand but its not the only one.......

2. The MI does not consider blade geometry i.e. section and width. One thing to note is that with the wider, thinner blades, type X and XIII immediately come to mind, well, with any sword for that matter - if the blade edge is not perfectly aligned vertically or horizontally, then there is a moment developed that will cause a slight bending force on your wrist when you hold it. its a small effect to be sure but the flatter/wider a blade the more this affects the handling and "feel" of a sword. its one reason I think why the narrower type XVIIIa,b blades often feel so nimble and maneuverable even at 1300-1400g whereas a wider flatter blade at the same weight feels more "substantial". the weight is just distributed differently within the cross section of the blade.

One further thing about POB. It seems to me, again this being my personal opinion, but POB matters in the absolute sense more than as a ratio. That is, the distance between your hand and the POB is what is important, more so than the POB as a function of the total blade length. Thats why I have struggled to figure out a way to explicitly include POB in some kind of descriptive index. its important enough in and of itself as well as blade section, length, weight

anyway thanks for feedback. tr
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Chris Fields




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PostPosted: Tue 05 Aug, 2008 8:00 pm    Post subject:         Reply with quote

What kind of engineer are you? I am a mechanical.

These charts are nice to follow, I would agree that POB needs to be included. I would include it in as a measurement from the guard. All other factors, ei; blade geometry, and amount of distal taper, effect the POB, so they do not need to be categorized.

When you pick up a sword, you feel a few things, first is the total weight if you pick the sword up vertically, and then the "feels like" weight when you hold the sword horizontally and the weight you feel is the moment created by gravity pulling on the POB a certain distance from your hand.

So, in your Mass Index, you could have a sword that is very long, and very light, but the POB is very far away from your hand. This sword would show "lively" in the MI, but in reality it wouldn't be lively at all. Make sense?

I think including the POB some how will make this chart almost perfect. Maybe you can directly relate the MI to the POB to come up with a "Liveliness Number".

The more I think about it, I think total length can be omitted and a simple weight to POB ratio would give you a "liveliness scale". right? Or am I over simplifying this? I am trying to think of an instance where this would not work.. but I can't think of one now.
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Bill Love





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PostPosted: Tue 05 Aug, 2008 9:11 pm    Post subject:         Reply with quote

There is, I believe, one more variable to add, although it will probably be the hardest to measure. I'm referring to the shift in performance that occurs when the blade goes from static to dynamic. If a heavy blade is fitted with a heavy pommel, it will feel good in the hand, in much the same way as a lighter, equally well balanced one-as long as the sword isn't moving. Actual use, however, will cause the heavier one to feel less lively simply because of the physics involved in moving differently weighted objects at progressively higher speeds. Add in the variations in density between seemingly identical blades, and you have one of the big reasons why many replica swords (especially the lower end ones) feel worse the faster they are used. Those Medieval swordmakers really were the rocket scientists of their day!
"History is a set of lies agreed upon."
Napoleon Bonaparte


Last edited by Bill Love on Tue 05 Aug, 2008 9:24 pm; edited 2 times in total
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Thom R.




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PostPosted: Tue 05 Aug, 2008 9:22 pm    Post subject:         Reply with quote

civil. i took statics too Wink I agree on all except for the fact that you omitted the part about the moment being affected by the mass behind your hand. so its not just the total weight and that distance between the hand and the POB. the mass behind the hand affects the resultant moment on your hand as the beam end is not where your index finger is at........ of course the problem is that a sword is an irregular beam, if we had a full 3-d model we could throw it into the 3d FEM which would be interesting if for no other reason than to see deflections due to self weight. (especially for longer swords). and we could calculate resultants for moment stability for any support point along the beam. but swords are relatively complex beams, in a way. i understand the issues as i originally said that it is only a very crude first approximation and that it tends to be a decent first approximation only for the case of very similar swords as in my Type XVIIIa example. the other reason i think that it works as a decent first approximation is that the POB for most swords lies in a very narrow range relative to the placement of the forward hand. That is, if this were a structure where we had many beams with lots of different geometrical configurations it would be totally meaningless, but we are talking about reproduction western medieval swords here (as i stated i excluded complex hilts), which 90% of them are constructed out of 0.25 inch stock, and have a POB within a very narrow range of 3-5.5 inches. most being in the 4-5 inch range. so the variability is there but not extreme as far as the position of the resultant POB. i know its crude but if you can come up with better i would love to see an example as i think we both can agree that we need to do better than "lively". you know what i mean.......

btw have you seen the discussion on the sticky thread on pommel weights on the historical board where the folks making swords are discussing pivot points? if so i would appreciate your take on that. thanks for the feedback, all criticism is welcome i am not one to take offense tr
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Thom R.




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PostPosted: Tue 05 Aug, 2008 9:30 pm    Post subject:         Reply with quote

absolutely true bill, the sword should basically be balanced properly even without the hilt components, and why changing out hilt components can often really screw up a sword.

as for pivot points, lets just say i am not totally comfortable with the way they are discussed in the community at times, i think there is confusion about pivot points, but in any case its a bit of a moot point because you don't see pivot point measurements on Albion's website ... do you? so we can only work with the data we have.

the basic problem of how a sword performs once set into motion is that the sword is not independent of the operator and so different people are going to experience the same sword differently. do you see what i am getting at?
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Bill Love





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PostPosted: Tue 05 Aug, 2008 9:46 pm    Post subject:         Reply with quote

You got it, Thom. POB would only have a chance at being a consistent predictor of performance if everyone held and used their swords in exactly the same manner, and maybe not even then. After ordering more than one "super sword" and being disappointed in their handling (at least in my hands) I've come to believe that what happens between your head and your sword is a much better "self adjustable variable" than what the sword specs out to on paper. I'm also going to go out on a limb here and suggest that cutting mechanics are only half of the equation; I believe that there is another factor, energy management, whose exploration has the potential to bring clarity to the study of everything from period illustrations to solo drills. Iconic martial artist Bruce Lee had this wired: unarmed, he could hit harder, faster and more precisely than opponents twice his size because his strikes worked on a deceptively simple force/inertia/force principle. If you watch an experienced Kendo practitioner, you will see that his bokken often seems to "float" in his hands at certain points in his cuts, and saber uses gravity as part of its operating parameters, so the idea as applied to edged weapons isn't at all far-fetched. After looking at quite a few images, Talhoffer's and Mair's in particular, I've noticed what could be interpreted as a tantalizingly similar trend in Medieval longsword. Based on illustrated hand and sword positioning there appears to be much, much more going on at the sword-operator interface than could ever be explained in writing. These guys obviously had every component fully tweaked and running at full speed. It would be a great thing if such a combination of factors could be quantified and combined with the Sword Mass Index; such a final set of numbers for a given sword would not only simplify the selection process but would probably be as close as anyone will ever get to picking the brains of the old Masters. Who said that the studies of individual performance and ergonomics are new things?
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Bram Verbeek





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PostPosted: Wed 06 Aug, 2008 2:41 am    Post subject:         Reply with quote

Another variable to consider is the angular momentum. I found that a stick with half the angular momentum and double the mass has a very different feel to it. What it changes is a somewhat weaker but faster cut for low angular momentum, and a slower but more powerful cut for higher angular momenta. In defense there is a huge effect as well, a low angular momentum is quickly in the right place, but is moved more easily, especially at the extremes of the blade, a higher angular momentum will take longer to get there, but will have more authority. Thrusts will not be changed that much, as they have little change in the angle, though they are greatly influenced by the distance between the leading hand and the point of balance. A heavier blade with a low angular momentum will tire you, but will have a quicker strike in the exercise.

Calculating this I did by calculating volume per 5cm increment, and multiplying that by the distance to the POB squared (mutiplied by the cubic density of the material, in this case 7.87, I used a long thread which had movable weights on it)

I found that I like a sword with an angular momentum in the area of 1,0 - 1.3 kgm2, a weight of 1,2-1,4 kg and a length of just over 110cm, while my friend likes a heftier 1,5-1,8 kgm2, a weight of 1,6-1,8kg with a length just shy of 120 cm This put me back to the drawing board to recalculate the various types. (XVIa for me and XIIa for Marcel is what I am planning now)
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Chris Fields




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PostPosted: Wed 06 Aug, 2008 7:37 am    Post subject:         Reply with quote

I still believe you guys are way over thinking this. I may be wrong and oversimplifing it, but please see below.

Bill - the relation of static to dynamic performance would be directly related to, and would be captured by, the total weight and POB. A blade with a heavier pommel will cause the total weight to increase, thus increasing that "liveliness" number

In your second post, you mentioned POB is dependant on the individual holding it. Well thats true, but this is comparing one sword to another. So, if one person compares one sword to another, would he hold the sword the same way? So relative to that person, the Total weight and POB would be a good predictor. For what Thom is trying to do, I don't think you can add in any measurements from the wielder, only the weapon being wielded.

Thom - Using the Total weight and POB does capture the weight behind the hand. I didn't omit it. It's captured in the total weight, and it effects the POB. The moment you feel is only dependant on the total weight and how far the POB is away from the pivot point, which is your hand. No need to FEM that. A FEM would be nice to see natural frequencies, COP, and stress and deflections during a cut though, I may be able to work on that. Furthermore, I believe you could categorize multiple type weapons on the same chart; EI: medieval single handers, hand and half, two handers, even sabers, Daos, katanas, and rapiers. I think we would see that results come out in groups correlated to their design. Saber would all cluster together, rapiers would all cluster together.. etc.

The balance points on the swords you were looking are very closely grouped, but correlated to the total wieght, a very small change in POB will give a high change in "liveliness"

btw... i haven't seen the pommel weight discussion

Bram - angular momentum is again dependant on two variables, total weight, and POB. So using these two numbers captures that as well. I wasn't sure why you brought Volume into the equation and squared the POB, but I like to know why you did. Thanks

I still think a simple correlation between total weight and POB will give you a good indicator of "liveliness" I'll see I can make some good charts up. The question is, how to corelate the two variables to come out with a system of numbers that makes sense. I am at work now, but I'll see if I can put some time into it.
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Justin King
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PostPosted: Wed 06 Aug, 2008 8:16 am    Post subject:         Reply with quote

Chris Fields wrote:


I still think a simple correlation between total weight and POB will give you a good indicator of "liveliness" I'll see I can make some good charts up. The question is, how to corelate the two variables to come out with a system of numbers that makes sense. I am at work now, but I'll see if I can put some time into it.



This is true only of a sword which is not moving. Take a decent handling sword, remove an ounce from the tip and an ounce from the pommel, and put these two ounces right at the COG, and the stats will read the same, and the sword will feel very similar when held still, but the handling will be drastically different once in motion.
A COG measurement to me just defines two halves of a sword according to mass. How the weight is distributed in these two halves is more pertinent to the handling equation than the location of the COG itself.
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Chad Arnow
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PostPosted: Wed 06 Aug, 2008 8:20 am    Post subject:         Reply with quote

Chris Fields wrote:
In your second post, you mentioned POB is dependant on the individual holding it. Well thats true, but this is comparing one sword to another.


POB doesn't change from one person to another. Whoever is balancing the sword on their finger or whatever should get the same number. Weight is weight. The point at which one part of the sword equals the weight of the rest is the same no matter what.

Also, POB isn't the most important determiner. There are swords with the same (or very similar) weight, overall length, and POB that feel different because the overall mass distribution is different. We have a number of Spotlight Topics on the subject that are worth looking into.

This is what Peter Johnsson had to say in this thread:

Peter Johnsson wrote:
To me the point of balance is one of the last points of reference both in understanding and in making swords, not the first or the most important thing. As has been mentioned before, these values is something that varies quite a bit between types and within a type.
Taken by itself it does not mean much.

What matters is how a cluster of aspects *work together*.
-Total mass
-Proportions of length between blade and girp plus overall size.
-Placing of forward and aft pivot point in the blade corresponing to the same in the grip.
-Placing of grip and blade nodes.
-Placing of point of balance.


So I wouldn't get too focused on POB, though it's better than just looking at weight and length.

I honestly personally wouldn't see a lot of value in a system that just looks at weight and length. Some heavy swords handle well and bely their weight. Some light swords handle poorly because they aren't engineered properly.

Happy

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Chris Fields




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PostPosted: Wed 06 Aug, 2008 8:43 am    Post subject:         Reply with quote

Thanks guys, this is a good discussion

Justin, I am not trying to be a jerk or anything, but I have to correct you. If you remove an oz from the tip, and an oz from the pommel, you will move the POB, The oz of weight out by the tip has a much longer moment arm and therefore effects the POB more than the oz by the handle that has a smaller moment arm from the POB, so the POB will shift towards the guard. if you put that weight back into the old POB, then yes, it will feel differently because the POB is no longer there, and you will be adding weight past the POB. If you put the weight into the new POB, then it will also feel different, again, because the POB changed.

Chad, what I mentioned about POB changing from person to person, was what I thought Bill was speaking of. That is a person may grip a sword lower down the handle, or closer to the guard, and that will change the POB distance from the hand, and that is what I was referring too, but you are correct, the POB on a blade doesn't change.

I like what Peter has mentioned, and I have read it before. I agree with him that Total mass is the first Factor. However, I still believe that total mass correlated to POB would make a good "Liveliness chart" if they are correlated correctly. The other things Peter mentions, aside from the grip and blade nodes, is dependant on the POB. The grip and blades nodes are dependant the blades cross section and harmonics.
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Thom R.




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PostPosted: Wed 06 Aug, 2008 11:17 am    Post subject:         Reply with quote

statically, what we ultimately want (i believe) is the moment force felt by the hand when gripping the sword just behind the cross. unfortunately since i don't know the mass density profile of the sword (which is a complex beam shape) i can't calculate that from the published measurements.

i posted the charts above because i am sort of at a dead end with it but now i am going to be building a rig in my lab for measuring moments on the hilt end of my swords when the support point is moved to just behind the cross. i think i will measure at two points, at the pommel end and at an arbitrary point behind the cross, say about 5 cm or so - about a half hand width. i will be reporting those out in the months ahead. i think it might prove interesting......

as for pivot points, correct me if i am wrong but this is how understand a pivot point for a single beam (sword)..... if i suspend a beam (sword) vertically (to remove moments due to self weight) with a suspension wire that ends in a loop or a u-bolt, which is itself suspended on a horizontal support wire, such that the sword can rotate around the supported end, and translate horizontally along the support wire, and then if i go to to the tip of the sword (opposite end, the bottom) and apply a horizontal force, the sword will tend to rotate and translate horizontally along teh support wire in the opposite direction of the applied force because i am pushing below the pivot point. if i apply a horizontal force higher, above the pivot point, the sword will translate horizontally along the support wire in the same direction as the applied force. the transition between these two regimes is the pivot point.

now i may be wrong but it seems to me that there is not a lot of sense in suspending a sword from its tip to find a pivot point at the hilt end because that pivot point is going to wind up being the tang/blade transition point in 99% of cases because of the radical change in the mass density profile at that point. also, pivot points in a beam or sword are entirely dependent upon where the support point is..... that is the pivot point for a sword suspended from the tang end is not going to be the same as the pivot point if we suspend the sword from just behind the cross where the hand grips the sword. the pivot point moves depending on where the support point is........ is that not correct?

thanks for all the responses! tr
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Thom R.




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PostPosted: Wed 06 Aug, 2008 1:08 pm    Post subject:         Reply with quote

Bram how did you calculate volume in your unit sections? did you just use a ruler and a caliper? i could see that as adequate with a diamond section blade but if flatter in cross section and with a fuller it would be tough to get volume right. but maybe i am missing something. i would think that with enough measurements, a 3d-solid model would not be difficult to build with the software i have, even in autocad it would be possible i suppose. we don't have one, but a shop near us has these pin cushions for developing 3d surfaces for building molds for no longer available parts. and multiple impressions using that actually might work, i dunno. we also have specialty modeling clays here, and i have thought about taking a piece of basswood, hollowing it out close to the profile of the sword, filling with clay, and then making a full impression of half the sword (wrapped in saran), and then literally measuring volume in the mold with water or fine sand of known loose density, slowly cutting away the mold section by section, remeasuring each time until i get to the tip of the sword and then calculate the differentials to get the unit section volumes, assume symmetry for the other half of the sword... and we're there - full mass balance profile of the blade. it sounds a bit involved but i bet i could do one sword in one afternoon if i had no distractions.

again, this is for swords in hand whereas my original post was for the case where you don't have the sword in your hand tr


Last edited by Thom R. on Wed 06 Aug, 2008 4:14 pm; edited 1 time in total
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Chris Fields




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PostPosted: Wed 06 Aug, 2008 4:13 pm    Post subject:         Reply with quote

I have several solid models of swords. Thats actually how I adjust total weight and balance point before I make one.

Thom, I still think you are over complicated the handling characteristics. The moment force would be the same as correlating the POB and Total Weight. I don't think you need to worry about volume. If you wanted to calculate the moment of inertia for each sword, you would need that, however, I don't think the human body could distinguish between moments of inertia of two different sword blades with the same total weight and POB because they would relatively very very close. I could be wrong though.

This is an interesting topic. I actually made some charts up of all the current Albion swords, ... however they are on my work computer and I forgot to email them to myself so I could post them here tonight. I'll post them tomorrow.
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Thom R.




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PostPosted: Wed 06 Aug, 2008 4:21 pm    Post subject:         Reply with quote

me? overcomplicate things ? Big Grin . i am going to forge ahead with a simple rig for measuring moment balance on my swords though and have already started to make it at lunch today. will report back on that and look forward to the charts! thanks much , tr
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Jean Thibodeau




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PostPosted: Wed 06 Aug, 2008 5:19 pm    Post subject:         Reply with quote

Sounds interesting although the math and such sort of leaves me lost. Wink Big Grin

But I wonder what the numbers on my OlliN " RavenWolf " would give you as a result and where it would be on your chart ?
http://www.ollinsworddesign.com/osd-custom-RW.html

My Topic thread on the making of the sword and my comments on it's handling, here is the link on the remote chance you may not have read it before. ( Well, I'm assuming you probably read it before since it's such a long multipage Topic and I don't want to sound conceited that you must have read it. Wink Cool ):
http://www.myArmoury.com/talk/viewtopic.php?t=8131&start=260

In summary at almost 5 pounds it's way out there in weight for a one handed but it feel as easy or easier to handle as my Gaddhjalt or Tritonia. My impressions are that it's very fast in spite of it's weight but total weight would tire one faster.

If I hold the sword vertically and wiggle it back and forth quickly it rotates around mid blade: Fast to rotate or move from guard to guard by rotating around this point rather than fighting against the swords natural way to want to move.

Very curious what impressions your number crunching would give you about this sword: Would it confirm my " In hand impressions " or would your numbers give the idea that it's a boat anchor ? ( Which it really doesn't feel like to me. Wink Laughing Out Loud ).

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PostPosted: Wed 06 Aug, 2008 5:55 pm    Post subject:         Reply with quote

Chris Fields wrote:


Justin, I am not trying to be a jerk or anything, but I have to correct you. If you remove an oz from the tip, and an oz from the pommel, you will move the POB, The oz of weight out by the tip has a much longer moment arm and therefore effects the POB more than the oz by the handle that has a smaller moment arm from the POB, so the POB will shift towards the guard. if you put that weight back into the old POB, then yes, it will feel differently because the POB is no longer there, and you will be adding weight past the POB. If you put the weight into the new POB, then it will also feel different, again, because the POB changed.

I used a poor analogy to describe what I was saying. You are right that taking an oz. from the very tip and an ounce from the very end of the pommel will change the COG in itself, but that dosen't change the basic point, which was another way of saying what has already been stated. That you can have two swords of the same overall size and weight, with the same COG, and they can handle very differently. You can move mass on both sides of the COG and make drastic changes to the way a sword handles without changing the COG itself, therefore many (including myself) do not consider this statistic plus weight to be sufficient to decribe the handling of a sword. It is far more complex than this.
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