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Jack Savante





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PostPosted: Sat 03 Nov, 2012 2:17 am    Post subject: Distal Taper         Reply with quote

I know alot is made of distal taper and its importance, but I have never come across formulas or accessible statistics for achieving distal taper similar or like historical originals.

Tinker Pearce commented that distal taper should be accelerating, presumably like a parabola. Peter Johnsson has inferred that distal taper needed to be non linear. Beyond that though I haven't been able to get alot of information on the subject.

Can anyone contribute to my knowledge on the subject? I'm really interested to know more.
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J.D. Crawford




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PostPosted: Sat 03 Nov, 2012 6:24 am    Post subject:         Reply with quote

In my opinion it depends on the handling and contact properties one wants from a particular sword. In terms of mass distribution it cannot be entirely separated from profile taper. In a broad slicing blade like XIII I like a concave distal taper whereas a sword with a stronger profile taper like XII, intended for both cutting and thrusting, may work well with a linear or even convex distal taper. Extreme thrusters may have no distal taper at all but rather maintain a stiff mid rib throughout. I believe, from limited observations in museums and reading, that these observations generally hold for historical examples, but that there are also no hard and fast rules. For example some XIIIs, apparently intended for very tough contact, had less distal taper. Swords were tools of war, designed for different purposes.

So if we can agree on that, the the question could be turned to: what type of distal taper is ideal for a particular type of sword?
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Robin Smith




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PostPosted: Sat 03 Nov, 2012 8:03 am    Post subject:         Reply with quote

I would be really hesitant to say a distal taper "needs to be" anything... Historical examples are as varied as the types of swords out there. There are as many examples of linear distal tapers as there are non-linear.

In fact I'd go so far as to say that modern sword collectors expect swords on the lighter nimbler end of the spectrum than what was common historically. Swords with 6+ inch CoG and fairly poor mass distribution were common. Alot of historical swords would have modern buyers turn up their nose and declared as "crap"...

A furore Normannorum libera nos, Domine
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Matthew P. Adams




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PostPosted: Sat 03 Nov, 2012 8:22 am    Post subject:         Reply with quote

Have you seen this spotlight topic?

http://www.myArmoury.com/talk/viewtopic.php?t...stal+taper

"We do not rise to the level of our expectations. We fall to the level of our training" Archilochus, Greek Soldier, Poet, c. 650 BC
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Jack Savante





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PostPosted: Wed 21 Nov, 2012 7:10 pm    Post subject:         Reply with quote

All interesting contributions, but I'm yet to find a guide / documentation / set of rules regarding particular sword types and their distal taper profile.

Before anyone goes saying "there is no hard and fast rules" etc. let us just accept that as a given. What I'm interested in is what was typical for a particular oakeshott blade type, or commonly found, or found on a particular example failing that.

Anyone out there?

Peter Johnsson seems to have taken plenty of data on sword thicknesses but so far hasn't published his findings unfortunately. I know Arms and Armor have documented many swords and Hank Reinhardt did as well. As far as I can tell from my searches on the net none of them have made public their data. I can understand why, it's valuable information that gives their businesses an edge over the competition, but I wish I could get access to it!
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Robin Smith




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PostPosted: Wed 21 Nov, 2012 7:44 pm    Post subject:         Reply with quote

Jack Savante wrote:
All interesting contributions, but I'm yet to find a guide / documentation / set of rules regarding particular sword types and their distal taper profile.

Before anyone goes saying "there is no hard and fast rules" etc. let us just accept that as a given. What I'm interested in is what was typical for a particular oakeshott blade type, or commonly found, or found on a particular example failing that.

Anyone out there?

Peter Johnsson seems to have taken plenty of data on sword thicknesses but so far hasn't published his findings unfortunately. I know Arms and Armor have documented many swords and Hank Reinhardt did as well. As far as I can tell from my searches on the net none of them have made public their data. I can understand why, it's valuable information that gives their businesses an edge over the competition, but I wish I could get access to it!

There are quite a few swords found here:

http://www.zornhau.de/category/fachartikel/
go to the section titled Vermessungsprojekt Dinkelsbühl and look at the measurements on some of the swords. You're gonna need to translate it from German, but most have tons of measurements including Distal Taper.

For example, take a look at ZEF-5. Its a classic Xa. The distal taper is 4.7mm at the base, 3.7mm 1/3 down, 2.7mm 2/3 down, and 2mm at 2cm from the tip. That's a pretty linear distal taper. The PoB of 7" (17.5cm) is pretty typical of this type of sword too.

There are other articles and PDFs to be found on the net...

I still think its a mistake to assume there is such a thing as "typical" distal taper. Distal taper is just one peice of the equation. Even in the same (!!!MODERN!!!) classification you will see alot of variance.

For example take type X with a thick blade of 5.2mm at the cross and compare it to one with a similar length type X that is 4mm at the cross. Obviously the blade that starts out at 5.2mm more can be done with the distal taper before becoming too thin than the 4mm blade, but the trade off is that the 4mm blade is gonna be much lighter. So you can't really talk about a typical distal taper without also factoring in how thick the blade is. Plus then you need to look at things like how deep is the fuller, since that will also have a profound effect on the mass distribution.

My point being, is you cannot look at just distal taper in isolation any more than you can PoB. You have to look at how all of it comes together. Does the sword work for what it was intended for or not? No one measure or metric will answer that IMO...

A furore Normannorum libera nos, Domine
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Jack Savante





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PostPosted: Thu 22 Nov, 2012 2:56 am    Post subject:         Reply with quote

Thanks for the link! Will get reading.
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Matthew P. Adams




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PostPosted: Thu 22 Nov, 2012 8:25 am    Post subject:         Reply with quote

The albion XVa blade actually gets thicker at the tip, at least my Fiore does.

If you sight down the blade, about ten inches from the point the distal taper starts to thicken, in order to support the narrow thrusting tip. The profile taper is so extreme on this style of blade that the overall mass still reduces as you move down the blade despite the distall thickening.

I have come to think of it in terms of mass reduction. The more spatulate the point, the more distal taper it needs. And with a more acute point, the less it needs. The important thing is that the further out from the hilt you go, the mass must continue to reduce so that each part of the blade is supported by the part behind it. Like a skyscraper.

"We do not rise to the level of our expectations. We fall to the level of our training" Archilochus, Greek Soldier, Poet, c. 650 BC
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Roger Hooper




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PostPosted: Thu 22 Nov, 2012 12:16 pm    Post subject:         Reply with quote

I wish that swordmakers and vendors would include distal taper with the rest of the specifications. Kult of Athena does this with many of their items, publishing the blade thickness at the guard and near the tip. I wish they would include one or two more measurements down the blade - top and bottom of the blade is a lot better than nothing, but more would be great.. At least it indicates that the maker is paying some attention to blade geometry.

Perhaps swordmakers don't want to publicize this stuff, feeling that the information is proprietary.

As indicated on this thread, there are different taper strategies, depending on how the sword should function.
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Matthew P. Adams




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PostPosted: Thu 22 Nov, 2012 2:34 pm    Post subject:         Reply with quote

I believe the folks at KoA actually get out a micrometer and take those measurements themselves. I really can't say enough good things about Ryan and company.
"We do not rise to the level of our expectations. We fall to the level of our training" Archilochus, Greek Soldier, Poet, c. 650 BC
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Chad Arnow
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PostPosted: Fri 23 Nov, 2012 10:36 am    Post subject:         Reply with quote

Robin Smith wrote:

For example, take a look at ZEF-5. Its a classic Xa. The distal taper is 4.7mm at the base, 3.7mm 1/3 down, 2.7mm 2/3 down, and 2mm at 2cm from the tip.


Not to nitpick, but you're listing thickness measurements in the last sentence quoted above, not distal taper. Distal taper would be presented in percentages or ratios of one measurement to the next/previous/rest.

Happy

ChadA

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Vincent Le Chevalier




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PostPosted: Fri 23 Nov, 2012 2:04 pm    Post subject:         Reply with quote

Roger Hooper wrote:
I wish that swordmakers and vendors would include distal taper with the rest of the specifications. Kult of Athena does this with many of their items, publishing the blade thickness at the guard and near the tip. I wish they would include one or two more measurements down the blade - top and bottom of the blade is a lot better than nothing, but more would be great.. At least it indicates that the maker is paying some attention to blade geometry.

Including more stats is not that useful if very few people (if any) are able to make something more out of it than "the maker is paying some attention to blade geometry". I mean they could use a vigorous assertion of that point and it would be equally informative Happy Including distal and not profile does not make very good sense either, since these aspects have to be related and work with one another.

As a user distal taper should not be something you look into. It's just a mean to an end, a way to obtain the appropriate mass and flex distribution. There are far easier and direct ways to measure just that.

Regards,

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Roger Hooper




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PostPosted: Fri 23 Nov, 2012 4:54 pm    Post subject:         Reply with quote

Vincent Le Chevalier wrote:

Including more stats is not that useful if very few people (if any) are able to make something more out of it than "the maker is paying some attention to blade geometry". I mean they could use a vigorous assertion of that point and it would be equally informative Happy Including distal and not profile does not make very good sense either, since these aspects have to be related and work with one another.

As a user distal taper should not be something you look into. It's just a mean to an end, a way to obtain the appropriate mass and flex distribution. There are far easier and direct ways to measure just that.



I respectfully disagree. It would be great if the buyer could handle, wield, test the sword in person. With the way the sword business is set up these days, all that one usually has are some photos and whatever physical specifications the maker cares to publish. One doesn't see the actual sword until one buys it and opens the delivered package.

Profile taper specs would be nice as well, though one can get some idea of that from the photos - distal taper, not so much. It seems to me that a sword designed for cutting more than thrusting like , say a type X should have some kind of distal taper (though I won't know if they did it effectively) If it has none, like some swords by dsa or the older Del Tins, I don't want to buy it. For a thrusting type XV with a lot of profile taper, obviously there will be much less or even none of the other kind. Even with blunts, knowing that a Hanwei/Tinker has significant taper and one by another maker has none, will tell me that the former will probably have livelier handling qualities. A description of the blade geometry won't necessarily give a comprehensive picture of the sword, but at least one will have more information available to help make a long distance purchasing decision.

If the maker doesn't want to publish those specs or indicate what the percentage is, then saying that the blade has linear or convex or concave distal taper to accomplish such and such a purpose would be more information that customers are getting right now.

What are "the far easier and direct ways to measure just that", that you refer to? Are they something you can do without having the sword in your presence?
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Vincent Le Chevalier




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PostPosted: Sat 24 Nov, 2012 12:15 am    Post subject:         Reply with quote

Roger Hooper wrote:
What are "the far easier and direct ways to measure just that", that you refer to? Are they something you can do without having the sword in your presence?

I've outlined a way to measure the mass distribution of swords in this article. In my opinion this is more informative than measures of width or thickness along the blade. Note that I'm still working on a better link to handling qualities from that sort of measurement, but the raw data discussed in the article is already much better (from a user perspective) than anything commonly published now.

I'm all for getting better stats online, as you say the nature of the market makes it very necessary. I'd just rather get the right ones Happy

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Matthew P. Adams




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PostPosted: Sat 24 Nov, 2012 7:53 am    Post subject:         Reply with quote

Hi Vincent,

I read through your article, and I found it interesting. However, your article doesn't seem to address how the distribution of mass effects rigidity.

Your method of measurement would give a very nice way to compare the feel in hand of different weapons, and whether they feel lively, but it doesn't take into account (I hate this term but I'm going to use it anyway) whipyness.

The taper, whether distal or profile, is important in that each section of the blade must support the rest of the blade from it, to the point.

Let me back up a little, if you look a reviews of less expensive manufacturers of swords... swords, the better reviews (handling wise) seem to go to the XV and XVa blades. As has been said before their profile taper means that less care can be given to the distal taper, and you still can get a sword that ends up feeling like a sword. The portion nearest the hilt has sufficient material to support the rest of the blade as you proceed out towards the point. So it has both good mass distribution and rigidity.

With a wider cutting biased blade that has little or no profile taper, the distal taper becomes much more important in order to get the tip mass down so that the base of the sword can support it.

If you go back to my comparison of a sky scraper, the bottom floors need to support, not just the floors above it, but the rest of the building as well. That's why the empire state building has a "concave distal taper" shape to it. Modern buildings that do not get narrower towards the top, use thinner and lighter materials to achieve the same reduction in mass.

...sorry, I went off on a tangent. My point is, I don't see your article addressing a way to measure if the weak of a blade has too much material in it which is what I understand to cause a sword to feel "whippy". When the weak overwhelms the strong during dynamic direction changes and results in over-flexing. If I looked over or misunderstood part of the article, please correct me.

And thank you for writing it, anything that furthers the understanding of sword dynamics is a welcome addition to the community!

"We do not rise to the level of our expectations. We fall to the level of our training" Archilochus, Greek Soldier, Poet, c. 650 BC
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Vincent Le Chevalier




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PostPosted: Sun 25 Nov, 2012 1:20 am    Post subject:         Reply with quote

Hi Matthew!

Matthew P. Adams wrote:

I read through your article, and I found it interesting. However, your article doesn't seem to address how the distribution of mass effects rigidity.
[...]
My point is, I don't see your article addressing a way to measure if the weak of a blade has too much material in it which is what I understand to cause a sword to feel "whippy". When the weak overwhelms the strong during dynamic direction changes and results in over-flexing. If I looked over or misunderstood part of the article, please correct me.


You're absolutely correct, I did not consider flex at all. I'm trying to get the first obvious effects right first, and this is mass distribution.

In order to measure flex, the obvious idea would be to clamp the hilt and attach a standard weight to the location of the blade mass, and see how far the blade deforms. If the blade flexes too much relative to the blade weight, then I guess it will be whippy.

My point is, even for flex you don't really need the details of blade tapers. More, the flex behaviour also depends on tempering and blade metallurgy in general, which is not measured at all by the tapers. So if this is of interest you need to design a way to measure it directly. Trying to figure it from tapers is far too complex, if at all possible.

Quote:
And thank you for writing it, anything that furthers the understanding of sword dynamics is a welcome addition to the community!

Thanks Happy
I have more in the sleeves, don't know how long it'll take me to write it all though Wink I'm already behind schedule for my next one Big Grin

Regards,

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Timo Nieminen




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PostPosted: Sun 25 Nov, 2012 11:25 am    Post subject:         Reply with quote

Vincent Le Chevalier wrote:

As a user distal taper should not be something you look into. It's just a mean to an end, a way to obtain the appropriate mass and flex distribution. There are far easier and direct ways to measure just that.


It's also a way to get an acute edge angle for cutting, or to maintain stiffness for thrusting. Or even about replicating historical thicknesses. It's not just about mass and moment of inertia. To see that some particular sword thins down to 2mm near the tip can tell you that (a) it cuts well with the tip, and (b) it's more historically accurate than most.

"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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Timo Nieminen




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PostPosted: Sun 25 Nov, 2012 11:31 am    Post subject:         Reply with quote

Vincent Le Chevalier wrote:
More, the flex behaviour also depends on tempering and blade metallurgy in general, which is not measured at all by the tapers.


No. Different steels have about the same stiffness. Pretty much all steel/carbon alloys short of cast iron have close enough to the same Young's modulus. Blade metallurgy and tempering affect the elastic limit, how far it can bend before it breaks or takes a set, but not the stiffness.

So, tapers should be enough.

"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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Vincent Le Chevalier




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PostPosted: Sun 25 Nov, 2012 11:46 am    Post subject:         Reply with quote

Timo Nieminen wrote:
It's also a way to get an acute edge angle for cutting, or to maintain stiffness for thrusting. Or even about replicating historical thicknesses. It's not just about mass and moment of inertia. To see that some particular sword thins down to 2mm near the tip can tell you that (a) it cuts well with the tip, and (b) it's more historically accurate than most.

Well that's assuming that (a) you have further data about the whole cross-section (as thickness alone does not tell you much about the edge angle) and (b) you have info of thickness on originals, which is not something common as far as I'm aware.

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Vincent Le Chevalier




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PostPosted: Sun 25 Nov, 2012 11:49 am    Post subject:         Reply with quote

Timo Nieminen wrote:
Different steels have about the same stiffness. Pretty much all steel/carbon alloys short of cast iron have close enough to the same Young's modulus. Blade metallurgy and tempering affect the elastic limit, how far it can bend before it breaks or takes a set, but not the stiffness.

Hmm, OK... I can't say I'm a specialist in metallurgy.

But then to use the info you actually need the whole cross-section, so tapers are still not enough. Just fullers will alter the behaviour of the blade...

Regards,

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