Titanium Sword / Katana?

Assuming equal mass, a fullered blade of equal height will be thicker(bad maybe) and stiffer(good) but a fullered blade of equal thickness will be taller (neutral) and less stiff(bad).

It isn't magic. It's just an integral over the cross section.

It's isn't automatically good or bad until you define acceptable parameters and give weight to conflicting properties.
 
Could a fuller reduce friction as a sword cuts through material by exposing less surface area against that which is cut?

Two blades of otherwise equal dimensions definitely behave differently if one is fullered and the other isn't. The fuller increases surface area (but exposes less to contact), and adds more structural cross-dimension with the sides and edge.
 
Phoynix said:
Umm what?
You said a unfullered blade is stronger then a fullered blade.. but weaker then a fullered blade...

I think you were trying to explain second moment of inertia but its really confused the hell out of me exactly what you were trying to say.

If fullered blades were weaker then non fullered blades of the same weight... then smiths wouldnt bother doing it.

All i can add is a proper fullered blade is done by forging, not grinding.
Two identical sword blades, the one thats fullered is stronger by up to ~30%, of course they are no longer the same blade profile.. but thats the point you are changing the blades shape so that its equal in strength to unfullered blades of more material.
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Negative. I said that, while the fullered blade would be stronger than a non-fullered blade OF EQUAL MASS, the fact of the matter is that if you grind in fullers, the blade starts out at a GREATER mass before fullering, unless you forge the fullers in, and to maintain the same proportions and measurements, you would STILL end up removing mass. The sword blade with more mass is going to be stronger, and there's no getting around that. So, while if you were to grind a fuller in, thereby removing material and weakening the blade, the new blade would be stronger than another blade of similar mass but WITHOUT fullering. But it's still weaker than the original blade that you started with.

Why do smiths add fullers? So that they can remove weight without losing too much strength. It's a compromise, not a magic bullet. And while the strength argument is true relating to blades of equal mass, it's NOT actually true in the real world to the original blade that has the fuller ground out of it. That's EASILY testable when making a blade. The initial blade blank resists deformation quite well. Once I've ground the fullers in, it's actually much easier for it to take a sideways set (or a twisting set, for that matter; I-beams and fullered blades are particularly weak to torque). You've made a logical error in that you're not actually dealing with a comparison between 2 blades of equal mass. You're dealing with a comparison between 2 blades with DIFFERENT mass but the same proportions. And the answer to THAT question is very different. Do the math, or just do some research. This stuff is pretty widely known.

Short version: fullering is just a more structurally sound way of distributing mass. But more mass is still more resistant to deformation than less mass, regardless of how you arrange the stuff. Making the original blade WITHOUT a fuller ground into it stronger than the same blade with material removed through fullering.
 
I heard of a sword that made a whistling sound over the fullers as you cut through the air, and each fuller made a different tone, so that when you heard both tones it meant the blade was moving through the air nice and flat, haha!
 
crimsonfalcon07
Lets ignore the fact you dont make fullered swords by grinding...

I will bite.
What exactly do you call strength when you say its weaker?
Are you talking

1. ultimate tensile strength
2. yield strength
3. Impact strength
4. Fatigue strength

Lets assume that the optimum depth and width of the groove is known to reach optimum notch strengthening for the fullered blade thats to be ground.
In a fullered blade 2,3,4 all increase, 3 only along the leading edge due to the spring like nature imparted by the groove.

Fullered blade can suffer greater force before permanent deformation, its higher fatigue strength means it can suffer greater abuse before it will finally fail, and greater impact strength along its leading edge could actually allow you to increase the edge temper without decreasing impact strength of the edge.

I would also argue that the increased temper could increase the ultimate tensile strength so its even or surpasses the unfullered blade so that its superior in all ways to the exact duplicate blade without a ground fuller.

You never stated they had to have the same temper and removing 30% of the material from a blade, and then recovering that strength with a higher temper isnt out of the question when the fullered blade can counteract the negative aspects of higher temper.. reduction in fatigue, impact, and yield strength.

only side effect could be possible reduction in strength under shear, so if both blades were to meet flat side its possible the unfullered blade could break the fullered one.. yet if they meet edge on edge the reverse is true, and the unfullered blade with a softer edge and lower impact strength along that edge would suffer greater damage.

But.. hey..im no expert ;)
 
That is just absolutely wrong.

But back on topic, are any of these in circulation yet? I checked Facebook and the Web page and haven't seen anything sold or for sale.
 
Phoynix said:
But.. hey..im no expert ;)
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Clearly. But whatever. You're still completely missing the point and working with an incomplete picture, so have fun with your fullers. FWIW, I can, and DO make fullered blades by grinding away material, be it with a fullering tool, a belt (or even an angle) grinder, or a mill. In fact, I would venture to guess that most fullers on most production blades are made with a mill, not with a forge. But, you are entitled to your entirely wrong opinions, and if you want to keep them, please, be my guest. It is the internet, after all.

Mecha, unless you're actually interested in this topic, I'm gonna just leave it be. My recommendation would be to just keep your blades as is. While I actually happen to like fullers, the benefit comes from weight loss without a huge amount of strength loss, and it doesn't seem like that would be really necessary for a Ti blade. I guess maybe if you did something crazy big? Which makes me think... Maybe your ti-blades would be well suited to fantasy creations--functional buster swords, perhaps, or the ridiculous katana-like blade that Sephiroth uses in Final Fantasy. The main issue with making those out of steel is, of course, weight. Ti might help?
 
Mecha said:
I heard of a sword that made a whistling sound over the fullers as you cut through the air, and each fuller made a different tone, so that when you heard both tones it meant the blade was moving through the air nice and flat, haha!
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Only if both notes were flat. What about sharp and natural notes? :)
 
Mecha said:
I heard of a sword that made a whistling sound over the fullers as you cut through the air, and each fuller made a different tone, so that when you heard both tones it meant the blade was moving through the air nice and flat, haha!
Click to expand...

If you get ANY consistent sound that has "depth" to it from a katana with bo hi(fullers), you are cutting properly.

Best Regards,

STeven Garsson
 
Nice, Horseclover!~

It seems like fuller discussions tend to turn into a shitstorm, hehe. Well I took a good look through my huge reference book on swords, I have bad news for everyone: you're all basically correct.

There are fullers of every shape, size and number, applied to every kind of blade imaginable over the last several thousand years. Most are forged into the metal (material rearrangement), some are chiseled out or created with material removal. Some of them make no sense, and many blades have no fullers at all despite being otherwise virtually identical to their fullered kin.

Furthermore, the fullers are located all over the place. Some are only smack-dab right on the main impact/cutting edge, some are only near the grip, others extend all the way to the tip.

Although the book's definition claims that fullers are made to reduce weight while sacrificing NO strength, by studying the hundreds of detailed photographs it's obvious that many fullers are not made for weight reduction. They are made for various reasons including:

-increased strength and/or rigidity due to geometry/engineering*
-artistic beauty/ceremonial purposes
-increased surface area (and apparent size!) using less material
-weight balancing/reduction

*This description from wikipedia says it well: "The basic design principle is that bending causes more stress in material near the edge or back of the blade than material in the middle, due to leverage...Fullers remove material from near this neutral axis, which is closer to the blade's spine if only one edge is sharpened. This yields stiffer blades of a given weight, or lighter blades of a given stiffness. The same principle is taken to an extreme in I-beams."

Thus, a diamond-cross-section sword does the opposite of a fullered one, adding MORE material near the neutral axis in a double-edged blade, yet still has a similar effect on the sword.

I think that "rigid" is the best term to describe what a fuller does, as opposed to "strength," which seems too absolute. A solid bar more easily gets waves of shock and harmonics reverberating throughout its length.
 
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