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Post by Deleted on Dec 20, 2007 13:41:15 GMT
Hello
I used to think that a sword's pivot point would naturally be its center of gravity (point of balance). However, apparently this is not the case. Some swords apparently have multiple pivot points! This leads to two questions:
1: What IS a pivot point? I can sort of see in my head how due to lever effects, the point where the sword wants to pivot around may not be it's center of gravity, but I'm a bit dubious about it. I also don't understand how can a sword have more than one pivot point.
2: How do you find a sword's pivot point(s)?
thanks!
Ancalagon
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Post by Jeff K. ( Jak) on Dec 20, 2007 20:19:45 GMT
I might be wrong in this but usually when you, say, move the blade from vertical to horizontal for a block you would twist your wrist and in doing so you can feel the weight/mass of the blade....to use the pivot point of the sword you use your shoulder more...kind of swinging your elbow out to drop the point of the sword. when you do this the blade feels lighter and you can whip it around faster. if you hold your sword out in front of you horizontally (if you're right handed, right elbow out, sword point to the left) and then swing your elbow in towards your body so the blade does an arc and ends up horizontally pointing to the right all the while keeping your wrist locked you can actually see the pivot point of your blade.(being the spot on the blade that moves the least).... hope you follow me...kinda hard to describe...
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Post by Deleted on Dec 20, 2007 21:12:29 GMT
True. In addition to the normal POB that between the pommol and the tip there is the balance down the blade length is you you hold the sword vertical and spin it (rotational balance) . A cruciform hilted norman style sword (type x) should spin like a top centered on its fuller or diamond cross-section. This is not often the case with sabers and rapiers. It can be and I personally prefer it, but you should not take it for granted that it will be as with a cruciform sword. I handled a beautiful Turkish saber from Badger Blades that was specifically designed to be balanced down the center of the blade. It is one of the few Badger Blades I handled that I liked. It was designed so the blade dipped down under the handle and then back up to form an "s" like curve. This is very important issue for a rapier fencer for myself. A lot of the blocking against hand-snipes I do is by rotating the sword and spinning the quillions. The mass distribution in the hilt and quillions makes a big difference in how fast I can rotate those quillions to block. I am sure you have seen my rapiers before: Compare to this: That knuckle guard is going to throw the rotational balance off a bit. Quite frankly even though it is historically accurate on rapiers, it offers little defense. It is far more practical on a saber or a cutlass where you are lifting you hand up to cut and exposing it.
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Post by Jeff K. ( Jak) on Dec 20, 2007 21:23:45 GMT
tsafa, so in esscence you're talking about a longitudinal pivot point? hmmm... that never even occured to me. cool
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Post by Deleted on Dec 20, 2007 21:28:28 GMT
Yes, I am not sure what the correct name of it is. I think I will call it the rotational balance for now. It is critical in rapier fencing. Not all rapier had symmetrical rotational balance. If you don't, you need to be aware of it and work around it. As it like to say, "You have to use a sword as it wants to be used rather then how you would like to use it".
Jak, when I read your post, I thought you were talking about the same thing I was talking about. Since you are not, you will have to explain it in some other way I can grasp.
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Post by Deleted on Dec 20, 2007 21:54:19 GMT
Stupid noob question tsafa but are you referring to the point of balance and how if you work with it you get a faster direction change than trying to muscle it with your wrists?
I've noticed that if I work around a certain point of these bastard swords that I can get a LOT faster than trying to muscle it from the handle using my wrists and forearms.
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Post by Jeff K. ( Jak) on Dec 20, 2007 21:59:41 GMT
centurion thats pretty much what i was getting at but i found what i considered the pivot point was further toward the tip than the POB. that may just be the characteristics this sword though
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Post by Jeff K. ( Jak) on Dec 20, 2007 22:02:45 GMT
i think what tsafas talking about is a point along th axis of the blade to get the quillions around while holding the blade point toward your opponent... am i right?
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Post by Jeff K. ( Jak) on Dec 20, 2007 22:24:27 GMT
ive got a JPEG sketch i did but im not sure how to uploade it here
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Post by ShooterMike on Dec 21, 2007 0:54:45 GMT
Here's a quick video I made late today to add to this discussion.
Tsafa, we aren't actually talking about the same pivot point, but I think they are likely inter-related in some way? On most cut&thrust swords I have tried, this rotational pivot point seems to lie somewhere between the Center of Percussion (CoP) and the Point of Balance (PoB). The exact location seems to be determined by a myriad of things. Some of them seem to be the distance from the hand to the PoB and the relative length of the blade.
Also, from working with Low Polar Moment (LPM) swords, I've noticed that the greater the percentage of the sword's overall weight that is concentrated between the hand and the PoB, the faster the sword "turns" in handling drills, since you're moving most of the weight a shorter distance.
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Post by Deleted on Dec 21, 2007 1:41:03 GMT
ooh, +1 karma for VIDEO instructions! I think tsafa is talking about a different "axis" of rotation - ie if he wants to twist his sword a bit like a screwdriver. Mike, this is pretty helpful because I really see the pivot point. But I'm perplexed at this point, because to me that pivot point would change on depending on how you move your arm.... ok I'm going to go try this in front of a mirror now... edit: Well that was interesting. My sword is a hand and a half practical from hangwei - definitely a different beast than a trust and cut sword. I tried duplicating your motion, and I could see there was a point there the sword seemed to pivot around, about 5-6 inches beneath the CoP. However, interestingly enough, I did it a bit "diferent" and instead of having the sword pivot around this point, it started swinging like a pendulum, with the tip not moving at all. I really wish I could explain - or heck understand - what was the difference between those two effects. What is "low polar movement"? thanks again, Ancalagon
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Post by Jeff K. ( Jak) on Dec 21, 2007 1:59:58 GMT
mike, thats exactly what i was talkin about...ah the beauty of video... anyway when you started parrying fencing style it looks to me like the pivot point is actually the same as when you hold it across in front of you..the blade point just travels less..so i think the pivot point tsafa was talking about earlier is the same
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Post by ShooterMike on Dec 21, 2007 2:33:07 GMT
Glad it helped. As for the locations of pivot points, they seem to change based on where you hold the sword. I can't really explain it, but I know Michael "Tinker" Pearce is an expert on it. I've read a lot of what he's written, and then discussed it at length with Gus Trim this morning. It all seems to do with weight, balance and force. It actually seems to be almost a gyroscopic effect in some way. It always seems to fall at a point between the extreme ends of the line formed by the PoB, the CoP and where ever you are holding the sword. But only if you hold it by the grip. I think what's really involved are the Nodes of Vibration, which helps you find the CoP. That's the Primary NoV. But there is always at least one other, located at the other end of the sword, usually in the grip. Here's an explanation of all that on myArmoury. Scroll down to "Blade Properties" for an explanation of the primary and secondary nodes of vibration. This is one of my favorite articles. EDIT: Oh, I almost forgot. Low Polar Moment is a sword term to describe a sword that's designed so that much of the weight is located between the hand and the CoP, and the PoB is fairly short. So the extreme ends of the sword, tip and pommel are light. That way, most of the weight stays near the pivot point. This is usually accomplished by making the sword from much thicker stock, then adding some pretty radical and non-linear distal taper during blade shaping.
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Post by Deleted on Dec 21, 2007 5:29:34 GMT
I've read that article previously, and unfortunately they don't touch on that subject ... I've been thinking about what you said, and did a few more tests in front of a mirror. First, I think that the point of pivot is NOT related to Nodes of vibration... per say. Rather, I suspect that the sword's properties that determine where the nodes are also play a role in the placement of the point of pivot. It sounds like hair splitting, but that's how a scientist's mind works sometimes, sorry (As an analogy, blood carries oxygen because it has iron in it, and blood is red because it has iron in it. However, blood doesn't carry oxygen because it's red). Playing around the mirror, I also noted that the tightness of the grip affects the point. Holding the sword loosely results in that "point of the sword not moving" pendulum effect, while grasping it tightly "lowers" the pivot point closer to the hilt (between the CoP and PoB). Low Polar moment - ah, that makes perfect sense. I wished I could instantly grasp the pivot point in the same fashion - perhaps it's one of those things I'll have to do a lot more sword handling before it really sinks in. Ancalagon
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Post by Deleted on Dec 21, 2007 7:01:57 GMT
i think what tsafas talking about is a point along th axis of the blade to get the quillions around while holding the blade point toward your opponent... am i right? Correct. I spin those quillions to protect my hand, so I need a sword that spins very balanced with minimum torque as I rotate my wrist. This is important to my style of fighting, but most rapier styles assume some minimal hand protection from the hilt. The balance along the axis of the blade becomes less important. I've noticed that if I work around a certain point of these bastard swords that I can get a LOT faster than trying to muscle it from the handle using my wrists and forearms. That is correct. It also cuts your range. Have you seen my Point of Balance video? Keep in mind that working off the POB is an option. You don't have to use it throughout a whole fight and you should not. While still in range but further back, you can rest the sword on your shoulder and hide it by holding your shield up. You can generate a lot of power from back there and they won't see it coming from behind your shield. You can then do a combination sequence off the POB as you close in. ShooterMike can has explained other concepts like the COP (center of percussion) and nodes of vibration. He is more familiar with those concepts then me. I don't use them in my style of fighting. I need to go back and reread what he said for my own education's sake. From what I see in the videos, that information can really be used to make awesome cuts. When fighting, I am less concerned with the perfect cut and more concerned with landing a good enough cut. So I will make a tip cut, cut with forte or cut with the back edge depending on what openings present themselves and what my position is at the time. These will be debilitating but will not cut a limb off.
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Post by Deleted on Dec 21, 2007 7:29:33 GMT
...i hate missing so much of these topics. Shootermike, I may be wrong, but the pivot point you find in your video just happens to look like(to me anyway) the halfway point between tip and grip of your sword. Based on the movement you use to demonstrate it, it would appear to be the same on all swords, regardless of harmonic balance. Think about it this way: Whenever you have a long object(sword, stick, etc) and it's rotating through a plane(i.e. during a cut), then it strikes something, the part of the sword that makes impact(we'll call this the 'Point of Impact', or POI) experiences a lot of force pushing back on it(Newton's third law). Now because the sword is all one piece, that force is expressed throughout the whole thing. Now for every POI, there is a Pivot Point that experiences NO CHANGE in momentum upon impact. (image borrowed from arma) In the second picture, the tan stick represents a standard swing, and the brown stick is the same swing that hit something, overlaid on top of it. You'll notice that there's a spot on both that maintains the same path - that's the pivot point... for that POI anyway. Pivot points are funny because there ISN'T JUST ONE on any sword. There are any number of them - each one corresponding to a different POI. So here's why this is important: 1. Whenever you hit something with a sword, force is felt throughout. 2. Feeling shock in your hands isn't fun. And can be detrimental to good cutting. 3. There's a spot on the sword that won't put much if any shock into your hand(the pivot point) when you hit something with the sweet spot(i.e. tip portion) of the sword(POI). 4. Ideally, this Pivot Point should be in the grip, just below the cross, where your hand is. 5. Swords can be designed this way - i.e. it's not a crap shoot. Now for some clarification: Swords are not clubs - When you hit something with a sword - it doesn't(or shouldn't) just bang on impact - the blade should actually continue it's motion through the target(i.e. cut through it). This doesn't change the fact that there's still resistance, and it should be minimized. So how do we design swords in this ideal fashion? Distribution of mass. The two bars of steel there are both the same weight, and both have the same PoB(point of balance). Obviously, the weight distribution is different and they thus handle very differently. It is for this reason that I'm not a fan of most wasters or wooden simulators - even the ones with the same overall weight, length, and PoB. Newstirlingarms wasters are the only ones that come close to having a more swordlike distribution of mass. Distributing where the mass is, and specifically - how much mass is in the POMMEL of the sword moves the pivot points in relation to the Points of Impact. And that, my friends, is the difference between a 500-1000 ATrim or Albion and a Gen2.
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Post by Deleted on Dec 21, 2007 7:49:27 GMT
Correct. I spin those quillions to protect my hand, so I need a sword that spins very balanced with minimum torque as I rotate my wrist. This is important to my style of fighting, but most rapier styles assume some minimal hand protection from the hilt. The balance along the axis of the blade becomes less important. That is correct. It also cuts your range. Have you seen my Point of Balance video? Holy smokes tsafa, that is an AWESOME video ... +1K. Very instructional and well presented. I have to admit that your voice has a thick yankee accent (well, to me) .... ;D Seriously though, thank you for posting that as it totally explains a different, but efficient way of fighting. I like you comment at the end about just needing a good enough cut. Reminds me of a quote from Stalin.
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Post by Deleted on Dec 21, 2007 7:49:33 GMT
As for finding the Pivot point of your sword...
Well that depends on where you hit with your sword. A lot of people like to hit with the CoP. That's just great, but I'm a fan of out-fighting, and as such ideally I like to strike with the tip(read: final 4-5 inches of the blade). finding a pivot point on a sword in relation to the tip is easy.
All you have to do is remove all external lateral forces from the sword but then apply a force perpendicular to the length of the blade, to the tip of the sword. this is accomplished by wearing a thick beefy glove, and balancing the sword on your palm by the tip, so the pommel is in the air. Move your hand in circles and one spot on your sword WON'T move - that's the Pivot Point in relation to an Impact Point on the tip of the sword.
Finding the pivot point in relation to the CoP is trickier, and requires some math. I'll explain it if you ask.
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Post by Deleted on Dec 21, 2007 16:53:58 GMT
As for finding the Pivot point of your sword... Well that depends on where you hit with your sword. A lot of people like to hit with the CoP. That's just great, but I'm a fan of out-fighting, and as such ideally I like to strike with the tip(read: final 4-5 inches of the blade). finding a pivot point on a sword in relation to the tip is easy. All you have to do is remove all external lateral forces from the sword but then apply a force perpendicular to the length of the blade, to the tip of the sword. this is accomplished by wearing a thick beefy glove, and balancing the sword on your palm by the tip, so the pommel is in the air. Move your hand in circles and one spot on your sword WON'T move - that's the Pivot Point in relation to an Impact Point on the tip of the sword. Finding the pivot point in relation to the CoP is trickier, and requires some math. I'll explain it if you ask. I would be very interested in seeing your mathematics.
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Post by ShooterMike on Dec 22, 2007 17:02:34 GMT
...Shootermike, I may be wrong, but the pivot point you find in your video just happens to look like(to me anyway) the halfway point between tip and grip of your sword. Based on the movement you use to demonstrate it, it would appear to be the same on all swords, regardless of harmonic balance. After looking at the video, I see that impression. I measured the pivot point on this particular sword. The overall length of the sword, from tip to pommel nut is 38.25 inches. The pivot point I feel when rotating the sword is just over 21 inches from the pommel nut. Leaving about 17.25 inches of blade tip in front of the pivot point. I don't care for that handling at all. So for the sake of experimentation, I replaced the Darkwood rapier guard with the original straight cross guard. The original guard weighs barely a third the weight of the rapier guard. This change moved the pivot point back to 15.5 inches from the pommel nut. Leaving 22.75 inches of blade tip ahead of the pivot point. MUCH BETTER! It has a lot more perceived "reach" from the same length blade. Looks like I kind of screwed up this sword by adding the rapier guard. It looks cool. But the performance in the cut has been severely degraded. With the original guard on, it looks funny with 2.5 inches of skinny ricasso in front of a simple cross guard. But at least it has been a learning experience, huh? ...Distributing where the mass is, and specifically - how much mass is in the POMMEL of the sword moves the pivot points in relation to the Points of Impact. Not only the pommel, but the whole weight of the hilt assembly. But I think that's what you mean in any case? ...And that, my friends, is the difference between a 500-1000 ATrim or Albion and a Gen2. Amen to that.
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