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Post by mattjohn98 on Jan 24, 2019 6:31:33 GMT
Hello Everyone
So regarding the topic at hand. I was wondering approximately how many times does it take for a sword blade to fatigue after being bent several times.
After doing flex tests on my swords, I found several of them take a set after bending over the knee. This is not necessarily a problem, because they do just fine in bottle cut test. However, I am somewhat paranoid on the fact that I have hit my cutting stand on a few occasions, and bent the blades. In the long term, how many times being bent will it take for the blade to fatigue?
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Post by Lancelot Chan on Jan 24, 2019 6:36:56 GMT
doing flex test ruin ur blade, period.
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Post by Lancelot Chan on Jan 24, 2019 6:40:57 GMT
several times of bending back and forth will totally destroy ur blades, depending on how far u flex them.
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Post by Adventurer'sBlade on Jan 24, 2019 6:47:25 GMT
My anecdotal experience: manually bending the sword will cause damage. Flex from normal handling and cutting with good alignment will not.
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Post by Adventurer'sBlade on Jan 24, 2019 6:52:12 GMT
Think of the sword's ability to spring back from abnormal tension as like a car's air bag. You want to buy a car with good air bags. You don't want to run your car into a wall to test them. Ideally the nanufacturer should do it and publish the results. Cold Steel's proof videos do this, but not in a very scientific or reliable way. But nobody else (companies) seems to do it.
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Post by Lancelot Chan on Jan 24, 2019 7:12:02 GMT
redmichael is right. the swords done with high flex test cant be sold as new.
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Post by Adventurer'sBlade on Jan 24, 2019 7:38:43 GMT
Proof videos may give some consumers the false impression that those feats can be performed without damaging the sword. What a flex test in a bench vise really shows is that they were able to perform that test, once, without catastrophic and dangerous blade breakage. The sword id now compromised.
I have a bunch of cold steel machetes. They are extremely durable due to being tempered for durability rather than edge retention and having solid plastic handles molded around a full tang. I still ruined one by burying it into a log and using it at a stepladder. Swords have limits.
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Post by Adrian Jordan on Jan 24, 2019 8:45:06 GMT
I believe it starts immediately to an extent. The steel molecules get displaced from where they ideally should be every time it gets bent to far, and that's no good. I remember in middle school doing an experiment in science class where you take a wire coat hanger or spoon and bend it back and forth several times. It gets hot at the point of the bend, then snaps. I know that historically swords often had to be bent back into shape after/during battles, though, so I can't give you a good answer on exactly how many times it takes before it is fatally weakened.
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Post by AndiTheBarvarian on Jan 24, 2019 9:06:14 GMT
I would't perform a flex test with bending the blade over the knee or head.
For a light test try to bend it a bit holding it - carefully - in the hands near tip and handle to look if there is some flex at all.
Then resting the tip on the floor or piece of wood and increase slowly and carefully your body weight on the handle until it flexes, so it flexes in a way the blade does it naturally in the right area of the blade.
Don't flex it too much and don't do this more than one time, than it should be no problem.
If a blade with good temper and flex stays bent I wouldn't trust it any more.
If a very soft tempered or not quenched blade stays bent you probably can bend it back without much (!) fatique.
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Post by leviathansteak on Jan 24, 2019 9:40:44 GMT
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Post by AndiTheBarvarian on Jan 24, 2019 10:09:48 GMT
Good read.
Many HEMA swords like feathers or afaik rapiers are designed to have an elastic deformation aka flex for safety reasons when trusting.
They will stand flexing much better than a stiff repro.
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pgandy
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Post by pgandy on Jan 24, 2019 13:53:05 GMT
... I am somewhat paranoid on the fact that I have hit my cutting stand on a few occasions, and bent the blades. In the long term, how many times being bent will it take for the blade to fatigue? I don’t know how you designed your stand. With mine I have a vertical post with a horizontal board attached with counter sunk screws. The two are rigidly attached. For cutting I lay a second larger board loose on the horizontal board and place my target on that. For those times I mess up and clip the stand the loose board takes the blow and absorbs much of the energy saving the blade and the stand itself from receiving all of the energy. I’ve played “pick up” a few times, but never bent a blade. Perhaps a similar arrangement might save a bend in your blade? |
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Post by mattjohn98 on Jan 24, 2019 22:03:58 GMT
I believe it starts immediately to an extent. The steel molecules get displaced from where they ideally should be every time it gets bent to far, and that's no good. I remember in middle school doing an experiment in science class where you take a wire coat hanger or spoon and bend it back and forth several times. It gets hot at the point of the bend, then snaps. I know that historically swords often had to be bent back into shape after/during battles, though, so I can't give you a good answer on exactly how many times it takes before it is fatally weakened. The reason I ask this is because they have bent more then once, and the steel seems fairly soft. Id say at least six times, including accidental bends. I have a wooden cutting stand. Do u think i should get a plastic cutting stand instead, that way it isnt as hard of material Im impacting. |
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Post by Adventurer'sBlade on Jan 24, 2019 22:06:41 GMT
Hang your bottles vertically on a string.
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Post by Deleted on Jan 24, 2019 22:25:51 GMT
List the swords and picture them if you can. I've tweaked this one many times in demos and will probably pay for it some day. A 110+ year old military sabre, bent by its own weight, just holding it by the tip. Returns to straight without a whimper.  It is an E.F.Horster blade from the early 20th century. |
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Post by Deleted on Jan 24, 2019 22:37:55 GMT
As to bottles, jugs, pretty much any cutting target. It is the cuts that don't that will cause the sword to absorb the most energy. Water weighs at about a pound a pint. That puts a 2 litre at roughly four pounds. So, if you are launching bottles like a baseball, that is a lot of stress.
Differentially heat treated swords, as with many katana, are more prone to bending and taking a set when the cutting is done poorly. Even well heat treated blades can get bent from poor cutting technique but they would need quite an effort to straighten and it shouldn't be easy to do so.
Again, without information about your bent swords, who is to say what is going on. or what you might have expected.
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Post by Adrian Jordan on Jan 25, 2019 0:22:39 GMT
I believe it starts immediately to an extent. The steel molecules get displaced from where they ideally should be every time it gets bent to far, and that's no good. I remember in middle school doing an experiment in science class where you take a wire coat hanger or spoon and bend it back and forth several times. It gets hot at the point of the bend, then snaps. I know that historically swords often had to be bent back into shape after/during battles, though, so I can't give you a good answer on exactly how many times it takes before it is fatally weakened. The reason I ask this is because they have bent more then once, and the steel seems fairly soft. Id say at least six times, including accidental bends. I have a wooden cutting stand. Do u think i should get a plastic cutting stand instead, that way it isn't as hard of material Im impacting. Sure. Hanging it on a string will remove part of the danger. The blade may still bend if poor alignment is used, as the container still has weight if filled with fluid, as edelweiss mentioned above.
Most swords will bend if done so over the knee. I've seen videos of guys just grabbing a sword by either end and bending it manually with their bare hands. Some blades are intentionally made soft(comparatively) and sometimes they just squeaked through QC and have a flawed heat treatment. Assuming that good alignment was used and the swings were not over powered then I'd say you have a sword with a soft blade.
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Post by Deleted on Jan 25, 2019 0:43:21 GMT
Is the height of the stand throwing you off? The things are very simple to put together yet it amazes me how many enthusiastic don't take the 20 minutes to get a platform sorted out. Even if it takes a few tries it's worth getting it right.
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Post by mattjohn98 on Jan 25, 2019 3:30:13 GMT
Is the height of the stand throwing you off? The things are very simple to put together yet it amazes me how many enthusiastic don't take the 20 minutes to get a platform sorted out. Even if it takes a few tries it's worth getting it right. I've been using my garbage/Recycling bin with a piece of a wooden desk top to cover it, so I don't hit my garbage cans. What cutting stand do you use? BTW the swords in question that bent are the Cold steel napoleon saber, 1796 light cavalry saber and Windlass Shasqua. |
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Post by Jordan Williams on Jan 25, 2019 4:08:31 GMT
By bending do you mean taking a set, ie bending and staying bent?
I would recommend hanging a bottle from a tree via string or cord. I use jute cord with a hangmans noose tied for the bottles so I can reuse it.
I'd also recommend doing drills! Most blades don't take bends in cutting soft targets, or even hard targets.
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