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Roberto C





Joined: 31 Oct 2013

Posts: 12

PostPosted: Wed 25 Dec, 2013 10:57 pm    Post subject: Distal Taper, is it that important?         Reply with quote

Lately I have been reading a lot about distal taper, it is a relatively complex subject (at least for me) because there is not some kind of "ideal" amount of it. I mean for a longsword, if it has a balance point of 1.5-5 inches it's usually considered decent depending of the Oakeshott typology and personal taste but when it comes to distal taper there is more variety, for example:

My tinker hanwei longsword had a thickness of 5.27mm at the base and 2.13mm at the tip. I took the measurements from a digital micrometer so I think they should be precise enough. But now if I compare it to an Albion Ringeck (I know they are not in the same quality category but I'm just using it for comparison) it starts at 9mm and ends with 3.7 according to the Kult of Athena page: http://www.kultofathena.com/product.asp?item=...War+Sword.

So a good sword does not always mean a similar distal taper, however the Hanwei tinker blade is flatter so that might come to change things. Also it seems that as a general rule, the more profile taper the less distal taper it needs. But what really bugs me is that how much weight of material can you remove by eliminating a few millimeters along the blade? I guess we will need proper calculation for this but I suspect it is not that much. Also I have been thinking that maybe a pronounced distal taper might not mean better thrusting as it is often implied because it makes the tip structurally weaker and will usually flex more than a lower taper and stiffness is a key part on the thrusting capabilities of a sword.

To make things short, do you think that distal taper is that important as it sometimes seems to be and why?
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Peter Messent




Location: Texas
Joined: 03 Jan 2009

Posts: 226

PostPosted: Wed 25 Dec, 2013 11:56 pm    Post subject:         Reply with quote

Distal taper is very important IMO; however, it is not 'set' - ie you can't say that every blade of X length should start at Y thickness and end at Z thickness. A combination of edge geometry, fullers, blade length + weight, handle length, crossguard specifics and pommel specifics all contribute significantly to the feel of any sword. Some swords have rather complex, concave tapers, others are linear and others have little - but the combination of all a swords properties make it feel right. That being said, in order to keep overall weight of the sword down and balance point favorable (particularly for longer swords), distal taper is necessary. Also note that a 4oz pommel on a 12" handle brings the balance point further back than it would on a 6" handle. As such, a sword's handling characteristics could, in theory at least, be defined by a (perhaps complex) set of numbers describing all of the relevant values. Of course that takes the fun out of it... but no, the distal taper of a blade alone really tells you nothing about the sword, except perhaps whether the blade is well designed and executed or not.

Also note that even good balance point is not set in stone. People often use the rule of thumb that closer to the guard is better, but that is just a casual estimation more than anything else. Early viking swords are generally pretty obviously meant for slashing cuts and hacking cuts - not for poking. The round, spatulate tip, lenticular section and often fairly parallel edges reveal this. XVII types on the other hand are clearly designed with the thrust in mind, with a good profile taper, acute point and more rigid diamond section. While either will cut and thrust soft targets, the ideal handling characteristics will differ - and thus, so do all the other numbers, from distal taper to pommel weight to grip length.

Without distal taper, great swords would probably have 2lb pommels Big Grin

Hope that helps some,
Pete

PS: After rereading your post I decided to address a couple points specifically, rather than just generally.

Quote:
But what really bugs me is that how much weight of material can you remove by eliminating a few millimeters along the blade? I guess we will need proper calculation for this but I suspect it is not that much.

True, the actual metal shed from the distal taper is likely not much - but it changes the mass distribution of the blade significantly, which means that the pommel can be much lighter while maintaining a good balance, thus shedding overall weight as well.

Quote:
Also I have been thinking that maybe a pronounced distal taper might not mean better thrusting as it is often implied because it makes the tip structurally weaker and will usually flex more than a lower taper and stiffness is a key part on the thrusting capabilities of a sword.

Cross section and fullering also play a significant part in the rigidity of a sword. Diamond sections are more rigid than lenticular, for example. Distal taper doesn't add to the thrust in the sense of the sword's penetration ability, but rather having the balance point closer to the hilt can make a precise thrust (ie trying to get in a gap between armor) much easier.

Pete


Last edited by Peter Messent on Thu 26 Dec, 2013 12:01 am; edited 1 time in total
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Timo Nieminen




Location: Brisbane, Australia
Joined: 08 May 2009
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PostPosted: Wed 25 Dec, 2013 11:57 pm    Post subject: Re: Distal Taper, is it that important?         Reply with quote

Roberto C wrote:
But what really bugs me is that how much weight of material can you remove by eliminating a few millimeters along the blade?
[...]
To make things short, do you think that distal taper is that important as it sometimes seems to be and why?


What matters for the handling is the mass distribution. The total mass matters, where the centre of mass is, the moment of inertia (the rotational inertia of the sword), and where the centre of percussion or pivot point is. Note that "centre of percussion" is used with two meanings. The older meaning is the same as "pivot point"; see "pivot point" on http://www.albion-swords.com/swords/sword-terms.htm

Distal taper doesn't remove that much weight, but it removes weight that contributes a lot to the moment of inertia. This also lets you control where the pivot point is. For thrusting swords, you want the pivot point to be close to the tip. A replica sword with less distal taper than the original can weigh 100-200g more than it should. OK, you might say, 1100g is more than 900g, but not that much more. But when the bulk of that extra weight is in the last 8" of the blade, it affects the handling a lot, turning an agile cutter into a clunker (I'm thinking of replica British 1796 light cavalry swords here).

"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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Lafayette C Curtis




Location: Indonesia
Joined: 29 Nov 2006
Reading list: 7 books

Posts: 2,689

PostPosted: Wed 25 Dec, 2013 11:58 pm    Post subject:         Reply with quote

This thread explains why it's so important:

http://www.myArmoury.com/talk/viewtopic.php?t=3154

Come to think of it, I'm a bit shocked about just how much insight has been shared in that thread by professional swordmakers and researchers. Makes me feel that the high prices charged by such high-end firms as Albion and A&A are pretty justified considering the amount of research their designers had to do and then throw away for free in public service posts like these.
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Roberto C





Joined: 31 Oct 2013

Posts: 12

PostPosted: Thu 26 Dec, 2013 12:32 am    Post subject:         Reply with quote

Thanks for the replies and the info.

Pete:
Quote:
People often use the rule of thumb that closer to the guard is better, but that is just a casual estimation more than anything else


I am aware that balance points are not set in stone so I used the term "usually" as a tendency in the sword community, but I agree with you in that regard.
Quote:
Without distal taper, great swords would probably have 2lb pommels Big Grin


That would be awkward Wink

Timo:
Quote:
Distal taper doesn't remove that much weight, but it removes weight that contributes a lot to the moment of inertia


This sums it up pretty much for me Happy .

Lafayette: thanks for the link, I'll read it, also I agree with the rest, sadly I can't afford one :/ some day...
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Nat Lamb




Location: Melbourne, Australia
Joined: 15 Jan 2009
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PostPosted: Thu 26 Dec, 2013 12:59 am    Post subject:         Reply with quote

using a pretty simple program and assuming steel has a density of 8.050 kg per litre, I made 2 models of a pretty normal longsword blade, 940mm long blade, 46mm wide at the base, 18mm wide 50mm before the tip and both 9mm thick at the base.*
Without any taper the blade would weigh 1086 grams. With a 50% taper it would be 982 grams. 104 grams might not seem like that much, but it also means a 10% reduction in overall weight of the sword. Moreover, the bulk of that weight reduction will be from the end of the sword, not the middle or the base.


*English and Philosophy major attempting to talk about something practical. Please excuse/correct all shifted decimal points and use of terms for weight when it should be volume etc.
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Roberto C





Joined: 31 Oct 2013

Posts: 12

PostPosted: Thu 26 Dec, 2013 1:05 am    Post subject:         Reply with quote

Nat Lamb:

104 grams is actually more than what I thought and it is significant indeed.

Would you mind telling me the name of the program you used?
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Nat Lamb




Location: Melbourne, Australia
Joined: 15 Jan 2009
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PostPosted: Thu 26 Dec, 2013 1:36 am    Post subject:         Reply with quote

err....
google sketchup. Blush
Really not what it is designed for, but I use it to make 3-d models of swords because I am not artistic enough to sketch them by hand, and not technical enough to use a proper 3-d program. I just used one of the volume plugins that are pretty easy to find.
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Roberto C





Joined: 31 Oct 2013

Posts: 12

PostPosted: Thu 26 Dec, 2013 1:47 am    Post subject:         Reply with quote

Have you tried autocad inventor? I learnt to use it 6 months ago in college, but it is not hard to use and it is pretty good Happy
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Gordon Alexander




Location: Eagan, MN & Dubois, WY
Joined: 24 Dec 2012

Posts: 57

PostPosted: Thu 26 Dec, 2013 7:02 am    Post subject:         Reply with quote

Any CAD program that calculates moment of inertia is very useful for figuring out where the pivot points will be. You can then experiment with tapers, profiles, and pommels to see how they change the mass, moments and pivot points. I use Rhino 3d and am quite satisfied. It is kind of fun once you get the hang of it.
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