Why swords have a fuller, part 2

[@My2CentsWorth1]

From someone with an engineering background, adding a fuller would almost never make sword stronger (resistant to bending) it would improve the strength to weight ratio, and that is one of the key principals in engineering. You sometimes trade a little strength for significant improvements in weight. This is particularly true when forces are expected only in one axis (the direction of impact).When you have a well edge aligned impact, the middle of the sword carries very little of the stress. For example, the following may not be historical, but it would be effective. You could drill holes or small slots along the length of the blade leaving a fairly strong blade, but with significant weight reduction. In fact, this sort of thing is more commonly seen in fantasy style blades, but it does serve legitimate function. It is a same that I am traveling and don't have access to my library. I keep thinking of cylindrical shells and I/T beams and channel shaped bars in my Mechanics of Materials texts.

[@zayanwatchel8780]

My2CentsWorth1 even then a sword needs some bend. If it doesn't have that if you thrust it against anything it could crack, or snap depending on shape.

[@Agent-Strawman]

It's the same principal as adding lightening holes in aircraft structures. And yes, I mean lightening as in "making lighter" not a misspelling of lightning. Punching holes in the web of an I beam or stiffener makes it lighter with a small effect on strength in the web direction (depending on how much material is removed.)

[@phylismaddox4880]

Wouldn't the cross section's actual profile change the equation?

[@bjarnivalur6330]

Remember: If you grind the fuller, you'll get dust all over the floor and in your shoes, and that's just annoying. Therefore you must always forge the fuller.

[@shadiversity]

+Bjarni Valur Damn that dust!

[@sirZOM]

+I am Shad (sorry for not posting in comments but copy paste doe not work there) thank for the video response i can better under stand your stance but to compare twp blades of the some type and add a fuller they both weight the same if forged to say it make it lighter is grinding and thus your first video statement of less metal make it weaker is true but does not have merit to forged fullers the question that is not answered is if you take two blade that are the same weight and length and add a forged fuller that widens both in x and y axis all be it more in the with portion forming more of an i beam shape will it be stronger. you mention adding a ridge it would help more than a slight thickness rise and more prevalent width increase but that is not the question that is about what is stronger a high ridge or a fuller . thank you for correcting me on the use of medieval grinders but that has no bearing on forged fullers. the use of other method may be better that is nothing to do with fullers capacity of strength to a non fullered blade of the same weight and length and metal i will end with this if you have two blade that are the same strength but one is fullered and light then making the ligher blade the same weight you would add thickness to the lighter thus making it stronger. i my opinion if the fuller makes a lighter blade as strong as a heavier blade you have to have some added strength or the blade is magic PS i find you very informal for the main point i do not agree with you but i can not fault your logic nor info and respect your conclusion if you have no further points then i am happy to end my statements here and call it an informal event

[@sirZOM]

+I am Shad to make what im saying posably more clear i will go threw your points about fuller in your second video 1)saving metal is more about why you might use a fuller not its strength 2) center compression mean you have expansion some where else in ether thickness or width likely both like you mention in 5:10 will add strenth 3)you state a fuller you can make a lighter blade but if the fuller has no strength benefit then you did not make a lighter blade a made a weaker blade and there is no reason to put a fuller when you could just use less metal to decreases weight when you can make flat non fuller blade and save you work with the same effect 4)you sate if you get a ridge form and if it forms an even expansion as you state at 10:15you have made i thicker and wider and a ridge makes it thicker thus form an i beam shape if a thicker blade is more ridged than an equal expansion in both thickness and width make it more ridged 5) at 13:10 you state a blade with a fuller would be lighter than one with out for equal thickness and width which i like comparing a rapier and a broad sword on is light but that is plank fact and refute its bearing on my statement at number 3 -------(you state a fuller you can make a lighter blade but if the fuller has no strength benefit then you did not make a lighter blade a made a weaker blade and there is no reason to put a fuller just use less metal with flat blade and save you work with the same effect)----------------------

[@Jiian]

+sirZOM If you are using firefox, this is a common problem. Go to about:config and scroll down to "dom.event.clipboardevents.enabled" and set it to false.

[@Caffeinated-Bladesmith]

+I am Shad Slight correction from an amateur bladesmith here. Quenching does not normalize the steel, it simply locks it in the current formation. The normalization process is called annealing, and entails heating the steel to ~1550° and slowly letting it cool. This allows the stored stress from moving material during forging to be realeased. If not done, all these stresses will release simultaneously due to the compressive forces undergone during rapid cooling. This could result in only a slight set that can be fixed in the 20 seconds or so the steel is still malleable after the quench, or something more serious like twisting or cracking. Many smiths recommend annealing 3 times, so I wouldn't recommend skipping it all together. ;) Nice video regardless.

[@robmurphy8572]

@@willyluciano9036 I'm a ameture smith and I do not have the tools to forge a fuller but I do have a grinder that can make a fuller. I would say forging it is easier and harder at the same time. Only problem with using the grinder is that it could be very wavy if you do not have eyes on the line or if you dont have steady hands. The easiest way for someone who doesn't have a lot of tools would be forging the basic shape of the indent of the fuller then filing out the rest until it's at the correct depth

[@graphixkillzzz]

actually, the normalization stage before the quench is what aligns the grains.

[@Gnurklesquimp]

And then the quench simply solidifies it so fast that it hardens before losing it's ordered state?

[@graphixkillzzz]

+M yep. the normalization stage consists of basically annealing the steel, which means heating the steel to austinite, then letting it cool as slowly as possible, 3 times. this kind of "heals" the stress fractures that occur from hammering below 800°F (500°C) and allows the grains to realign themselves.

[@Gnurklesquimp]

sess Ah cool, thanks for sharing the info!

[@Muudge]

so the process that sets the steel's structure back in place is the heating pre-quench, and then the actual quench.... sets it? hardens it? I understand that a quench through whatever science it uses somehow hardens a blade, but i don't understand what's actually happening and why you would quench a sword two times. Also... what actually is tempering? all I've seen is that you put a blade in an oven and then wallah, it's good-er after a little while

[@graphixkillzzz]

Mudge iron atoms form a box shaped molecule. when carbon is introduced, it gets trapped inside the box and the molecule is called ferrite (unhardened steel). when you heat the steel to ~1340°f (730°c), the structure expands, allowing the carbon atom to drift out of the box (this new structure is called austenite). cooling the steel very slowly allows the carbon atom to drift back to the center of the box (annealing), but cooling it rapidly (quenching) traps the carbon outside of the box which forms a new molecule called martensite (hardened steel). at this point, the iron box molecules get skewed into irregular shaped boxes (like 3d parallelograms), and is very brittle, almost glass-like. the last part, tempering, heating the steel from 350-650°f (175-350°c) for a few hours relaxes the molecules by allowing the carbon to drift just a little bit into the iron boxes. over all, when the carbon atom is in the very center of the iron box (ferrite), the molecule is much smaller, when martensite is formed, the molecule is expanded due to the position of the carbon atoms. this is why warping occurs when you harden steel. the Japanese control the warping in a process called jaki-ire (pronounced "jack-ee-day"), in which they cover the back edge of the blade with a thick layer of clay that stops the steel there from cooling fast enough to form martensite, thus the difference in the size between the smaller unhardened ferrite on the back edge, and the larger hardened martensite on the cutting edge, causes the blade to curve into the familiar Japanese weapons. not that you asked about Japanese weapons...just thought I'd give an example 🤔

[@Duke_of_Lorraine]

One point about the sword vibrating, I believe Matt Easton made a video about that : a well-balanced sword, yes it vibrates, but the vibration nodes (where you don't feel vibrations) are at the handle and at the center of percussion, the part of the blade you use to strike in the first place. Having a sword vibrate more is therefore no problem if the sword is well designed.

[@1forge2rulethemall88]

+scarfacemperor Depends on if edge alignment is correct if it's off it will deflect off, that's why blades without fullers (or hardened steel) are such good cutters, they don't vibrate and so they don't "bounce" off.

[@1forge2rulethemall88]

Nestor Simos I would think it would improve stiffness but I don't know the cost versus benefit between weight and springiness.

[@sixtoramos6323]

In my experience as a bladesmith (and talking from a handmade/historical perspective), forging has two main advantages over grinding: time and precision. And the first makes a great difference. Forging a fuller (or a bevel or any other part) takes about a tenth of the time it takes to grind it. Even today, with machine powered belt grinders, you save a lot by forging. In old times, working a water/human cranked grinding stone, it might have been worse. Of course, if we talk about modern industrial processes (CNC), the thing is very different... About the ridges, you can't get the kind you see on certain swords by forging the fuller. You get them by forging the fuller and then, forging concave bevels at each side. If anyone needs and example, steel behaves exactly like plasticine (heavy and really hard plasticine made of iron, but mechanically similar). And about the general topic of this (and the previous) video, I agree and desagree at the same time. Yes, fullers don't make the sword stronger. They actually make it weaker, but marginally. The difference in weight is far more important. The right heat treatment is even more important. That's my oppinion, anyway...

[@PsylomeAlpha]

Would it be possible (as well as an intelligent thing to do in the first place) to make the fuller die you use to hammer it in in such a way that it also hammers in the ridges?

[@sixtoramos6323]

+PsylomeAlpha It wouldn't be practical, because in a well made blade, you forge distal and profile tapers, so the geometry (distances, angles...) of the blade chages gradually, and one die wouldn't do the work.

[@PsylomeAlpha]

***** thanks! wanted to know from one who has walked this part of the path before me if they thought it would be practical before going to the effort of making the dies like that. I guess if you were going to make an industrialized method that pretty much hammered and stamped out the basic shape of the entire blade at once from heated stock that would be the only practical method, and even then that would require far more demand for practical swords than there currently is.

[@sixtoramos6323]

+PsylomeAlpha You're welcome. And yes (and speaking from a historical/antique perspective) it might make sense if you wanted to arm an army with very simple, identical weapons. I imagine "gladius" factories in ancient Rome might have had something similar...

[@alihaggis78]

I'm no sword expert but as someone with a engineering background, I'm amazed nobody has touched on what, to me, seems to be a big advantage to having a fuller in a sword. swords are mostly used with scabbards which fit the blade fairly closely to prevent an annoying rattle. When you put a sword into a closer fitting scabbard you are basically making a pneumatic piston. air must push past the blade and escape the scabbard to allow the sword to go in and the opposite when drawing. a fuller allows a path for this air flow making insertion and withdrawal much easier. It is even conceivable that a lenticular blade with a very close fitting scabbard would prove extremely difficult to draw.

[@isaacrichards1531]

alihaggis78 My experience, at least with daggers, is that the blade is secured with the hilt and the scabbard, not the blade and the scabbard. There has always air between the scabbard and the blade.

[@Tauntaun707]

Just put a hole in the bottom of the sheath and you solve that problem but I don't know if authentic sheaths were particularly air tight or not.

[@grayblackhelm6468]

Nathan Colburn Traditional scabbards actually come with metal ends on it, one for the mouth and for the point. To protect the steel.

[@Agent-Strawman]

That was the thinking that got people to call them blood grooves in the first place. Stab a flat blade into something squishy and it gets vacuum sealed in the stab wound. Add some grooves (or holes, or skeletonize the blade if you're really cool), and it's much easier to pull out. But this was probably thought up by the same people who thought European swords were stabby swords and not cutty swords.

[@shepardw4981]

A very interesting observation and as many scabbards are as you say very close fitting. You would want to be able to pull your sword from the Scabbard as quickly and easily as possible like a gun from a holster. Also it may have another benefit as like lead weights on a chrome rim. you could affect the balance of the blade by having 3 Fullers that go only halfway or one Fuller that goes all the way to the tip. ET cie

[@markisaacson7677]

9:00 The more I think about it the more I am convinced. The Fuller reduces the overall surface area when cutting to reduce jamming and to create a deeper cut. The fuller cuts out nearly 50% of the surface area leaving a sharp, but strong blade, but with much smaller surface area. It is like having 2 separate smaller lighter swords in one, but almost the same strength as one without a fuller.

[@MadNumForce]

Considering the grinding vs. forging debate, in pre-industrial times it's not an issue. Since laminated steel didn't exist, and you couldn't just angle-grind a blade from a stock bar or sheet, everything had to be forged from a shapeless ingot. Fullers were forged as part of that shaping process. The thing you overlook is that a bit of grinding is necessary to remove the thick forging scale and even the surface. But it makes no sense, when you have to forge a whole blade, to leave it plain and solid, and then take it to the grind wheel and make the fuller "from scratch". You can sure leave a bit of extra steel in the fuller during the forging to allow for some fine grinding work, but most the fuller is forge-shaped. It's simply how you do it by the book. The only exception I can see is when there is really a lot of fine work to be done on narrow or shallow fullers, such as on cinquedeas or openwork ornate 17th-18th century rapiers. Another thing: hammering hot steel doesn't at all mess up the cristaline structure. Actually, work hardening austenitized steel refine the structure. Work hardening itself improves mechanical properties: it increases Young's modulus and yield and ultimate strenght, but at the expense of ductility ("A%", as often found in datasheets). Of course, past a point, the steel just fails, and that's what happens with old splitting wedges with their cracked edges. But overall, work hardening is never a bad thing when you're looking for strength. And if the austenitic grain has been significantly reduced in size through work-hardening, re-austenitizing it wont "undo" it all, especially if you go low in temperature, and for only a short period of time, which is what you want to do for a quench. Even normalizing won't do much structurally. Only annealing cycles will really start to allow for grain boundaries to reconstruct. (Time X temperature) is the factor for grain growth. I'm working on a detailed image to explain what is really about fullers, weight, "strength", etc... because these things need to finally be right. I can't just let people say that fullers weaken swords.

[@RaggaDruida]

I have a theory about how the fuller would affect vibration, reducing the vibration created when hit, by helping to make the sword more stiff in the wide plane... When i have more free time I'll try to do the mathematic model...

[@kynaston1474]

The blade can still be lighter with a forged fuller, you just start with less metal. The real reason for forging a fuller though is so that you don't have to do as much grinding later. I am a bladesmith, it's what I do for a living. There can be some truth to the crystalline structure claim but only if you employ differential tempering methods. When you heat steel as we all know it becomes malleable. When you suddenly cool the blade by dropping it in the quench you are thermal shocking the steel causing the molecules in the steel to crystallize. This allows for a sharper blade. If the steel is allowed to cool slowly the arrangement of molecules in the steel remain less organized therefore more malleable and thereby more shock resistant. By differentially tempering the fuller during the quench by protecting it with say a clay coating you can cause it to cool slower than the edge. This way you come up with an edge that is extremely sharp and crystallized with a fuller that is malleable and withstands shock better. If you dunk the entire blade unprotected into the quench then the entire blade becomes crystallized and is therefore more brittle this can be a problem whether the fuller is ground in or forged in though. Grinding imparts heat to the blade ruining the temper so the quench is usually applied after grinding anyway. As for forging compressing layers you are correct in stating that it does not increase the strength of the angular cross section at all.

[@matheusb.dambrowski4639]

wow

[@Gnurklesquimp]

Haha I couldn't stop thinking about this throughout the video.. | was seriously questioning why you wouldn't simply start with less if you were to forge it in. I'm no expert but if both were viable options, I imagine forging to be more time consuming but grinding to wasting metal. And if the difference in time it takes ien't THAT big, ofcourse it could be worth it to save a little metal instead of a little bit of time. It would really just depend on which of the two resources is worth more to you at the time. You don't want to neglect the little numbers if you ask me

[@kynaston1474]

M Grinding is the most tedious and time consuming thing I do. Forging anything is almost always going to be quicker than trying to grind it in. Somethings have to be done on the grinder though. Come to think of it, I might just drop a fuller on the blade I just started working with, it has some serious weight issues.

[@Gnurklesquimp]

Adam Bodford Ah, I see.. Maybe the benefit would simply be that you can more easily modify the fuller if you're not satisfied after the forging process? I would think that proper planning could prevent that on bigger scales though.. Maybe it takes less craftmanship to do a decent job of it, simply making it the only option when you don't have a sufficient amount of smiths with good expertise but still need to produce large quantities?

[@kynaston1474]

I don't exactly know why forged fullers would be considered superior other than display of craftsmanship, forged fullers are difficult to do evenly. Grinding even on a large scale is very consumptive of abrasive resources and tends to waste a lot of metal. I wouldn't imagine it would be great in that regard either.

[@The1Helleri]

I know you've an understanding of modern tools. However I don't think you understand how older tools work. A manual powered grind stone (and even early motor driven ones) isn't a fast machine. It turns very slowly and works on the idea of redistributing surface grain more than removing material. It's literally not capable of grinding a fuller (without ruining the stone). Very few tools medieval Europeans had available to them are. The picture of an old grind wheel getting up to speed, and having steel touched to it, resulting in sparks flying is pure Hollywood. What tools they did have that could do this (rasp and file) would have made it a long and intense process. Hence why fullers were far more conveniently forged. I believe the creation of fullers via stock removal is an almost wholly modern technique. I also believe the idea that the fuller was ever implemented (before modern processes and the age of electricity) to reduce weight is a presentism. As for your understanding of shapes and the physical properties that they impart to structures. You really do need to know the math (more specifically the base facts, and formulas used to calculate strength against different types of forces given the material and the method at play) in order to be able to speak to it accurately. Reasoning it out absent the prerequisite knowledge and illustrating your reasoning via diagrams simply won't get you there. To that end I would like to offer the lend of one of my textbooks on the subject. The book is: Strength of Materials - by Mansfield Merriman, 5th edition 1910 (the age isn't really a factor for factual accuracy as this is a hard science and what we know of it has not changed much over time). It's a small book with plenty of figures, charts and diagrams accompanying the presentation and explanation of the information. It's a slow read for being such a small book. But if you can do high school math well enough. Then it's comprehensible (it starts from there and teaches you the math you need to know as you go). It weighs 348g and measures 20.32cm x 11.45cm x 1.27cm. So I don't expect it would cost much for me to ship to you. Or for you to ship back when having finished it. If you are interested send me a message on youtube.

[@xrexc3179]

In other words he's talking out his ass... yes I concur.

[@gurkfisk89]

While I'm no mathemagician, I have taken enginering courses that deal with this and the maths aren't that complicated in this case. And the easy anser is that if you have the same weight of the sword and the same edge to edge distance, having a fuller in the middle of the blade would increase the stiffness in both the flat and edge direction. As seen in your example around 10:15. Even without the ridges, just thickening the blade next to the fuller will help. This is because it's about the distance away from the center squared that matters. We also have to consider what we mean by "stiff" and "durable" in this case. By stiffness we mean how much force is needed to bend the blade and is called flexural rigidity. For durability we have section modulus that correlates the maximal momentum can be applied before you reach maximal stress in the material (how much load before the blade will break or stay bent). And here's the maths: The Flexural rigidity is equal to E*I where E depends on the material and I is the "area moment of inertia" as defined as the integral over the crosssection I= §z^2 dA where z is the distance from the neutral axis to the area segment, dA. (The neutral axis in our case is ofc the middle of the blade). So if you move a volume of steel 2 times further away from the axis, it will provide 4 times as much stiffness. For durability, the section modulus, S, canbe calculated by S = I/z_max Where z_max is the distance from the neutral axis to the most extreme area segment. (In our case z_max = half the blades thickness). By having a fuller we place more material further away from the neutral axis and this will increase I exponentially and therefore both the stiffness and durability will increase, if we consider the same total volume and not increase the width of the blade.

[@erikmmccray]

hi just stumbled on to this by accident. I know nothing about swords but I work as a metal fabricator. My experience tells me from making other things with similar design is its not to make it more stiff but to change how it will deform under load. With the kind of double dimond shape your showing it mades it have two conected spines that under ether vertical or horazonal load the two spines will twist around each other rather rather then bend in one direction. So I don't think they were trying to make the swords stiffer or cooler looking but make it just be able to take more abuse before failing. If you want a quick example of this take paper and fold it in a zig zag patern and compare its ability to take loads on it edges compared to a flate piece of paper.

[@scollyb]

You almost had a point you missed in both videos, you said you can make the sword, longer or wider for the same weight. But you can make the sword longer, wider or thicker for the same weight. Two swords of exactly the same length, width and weight one with a fuller and one without. Which is thicker and hence stronger on the flat? Note that doesn't require a ridge you can just make the sword slightly thicker in the first place

[@fuzzlenutberry]

By reducing the blade weight you also reduce the weight needed on the pommel to balance it, so for every bit of steel you remove from the blade you actually reduce the overall weight by double of what you removed. Something for those who think "it doesn't reduce the weight that much" to think about.

[@foolwise4703]

Again, you miss the point. Steel does is not permanently compressed in forging. Let alone strengthened by beeing more dense due to forging compression". In fact, its density will keep constant not matter how you forge it. Now to the crytalline argument. Yes, a tempering is done after forging. But this is not a recristallization heat treatment, but a tempering heat treatment. That means, that the cristalline structure is not reset by the heat treatment, but only the phase composition (martensite/ferrite/perlite). What can be done by forging is so called deformation hardening. This does happen uring forging, but I plainly do not know if this effect is significant in fullers. (I am a engineer for laser physics, not a mechanicl engineer. The way I understand this is that the deformation hardening strengthens the metal inhomogeniously in the direction in which the cristalls are deformed. That would make a forged fuller slightly stronger to resist blows to the edge and slightly weaker to blows to the side of the sword. But again, this is a kind of half baked knowledge/speculation on my part. If any material scientists are here - please clarify.) And again no, you are NOT loosing surface area by forging a fuller. The volume stays constant during forging. So unless you make your sword longer, the cross section will stay constant as well, and it will be further away from the middle, STRENGTHENING the blade. In BOTH directions! As for the math to calculate bending resistance of a cross section: dake any small (infinitesimal) surface area, mutiply it with the distance to the bending axis to the power of two, and do that for every small surface area. Sum all the results up and you have the bending resistance, missing only some constants for material strength and such. In mathematical terms: Surface S, distance to bending axis r: Strength = (Integral over S){r^2}dS Here is a good explanation: www.bu.edu/moss/mechanics-of-materials-bending-normal-stress/

[@Strategiusz]

No, in my opinion a fuller can make a sword stiffer compare a sword without a fuller but with the same mass. The sword with the fuller can have slightly larger the maximum thickness which is the same as it would had ridges. All it matters is mass and geometric sizes, no matter how the fuller is made (grinded or forged). Of course some fullers are just to make a sword lighter with the minimum cost of stiffness, but if you don't need the lighter sword you can gain the stiffness. In some combinations you can have both.

[@biscuitsalive]

The amount of steel you could save out of grinding away two big fullers on a long sword would be at least enough for a dagger. So it’s not a inconsequential amount saved by forging a fuller in opposed to grinding. And when you are making hundreds of swords to equip an army. That adds up to a lot of iron wasted.

[@jvmiller1995]

One of the benefits to forging, is that forging them in is a much faster way to make. Also after forging most masters will forge it and heat it up to temp and let it cool slowly. This takes any temper or uneven grain structure and stresses out of the steel. We refer to it as a thermal cycle and some of the really high end bladesmiths might do it 2 or 3 times to insure no stress are in the blade. Then it is brought up about 50 degrees hotter than a when a magnet no longer sticks. Then they queench normally in oil and it makes it cool fast but not so fast so it becomes hard but not so fast it could become to hard and become brittle. Quenching in water will almost always cause the grain to crystalize like sugar and break. Then most often the blades are so hard they are some what brittle so they anil them buy heating them up to 400 to 450 for about 20 minute and then they take on the springy feature and are as strong as they get. As for fullers with a raised edge one way it to do a hollow ground between the fullers edge and the blades edge. This will make the sword way lighter than just the fuller. As the majority of the blade thickness is removed and leaves to elevated ridges a long the sword. so if a person compares this to a sword the same size but with a flat blade only as thick as the thin fuller or hollow grind than the fuller sword is going to be much much stronger. But to take 3 Identical swords and forge a fuller in one and grind one in to another and leave the third flat... The flat steel that is full thickness is going tr be stronger. But the benefits was you can make a lighter sword that is easier to swing and still be stiff enough not to bend or brake. And I promise forging the fuller will be a faster process and you can make more swords a day. Grinding them is precise but it is slow. So if it was a ceremonial sword or for a nobel blood it would most likely be ground as they was meant to make a statement about the owner. But they can be forged in and then ground to dress them up more perfect. But forging them would be way faster especially with old non power grinders.

[@bengrogan9710]

+I am Shad Thankyou for addressing what I was trying to say with the longitudinal strength, however I believe you may have misunderstood one of the points I was trying to make, I was also the one who made the point on the crystalline structure: Perhaps i was not clear how and I shall attempt to clarify as best i can. Before i start Disclaimers, different steels, and different materials behave very differently and as such I am making no claims with regard Bronze weapons, which work harden and become brittle very easily and I am only here referring to forged fullers 1st as to the crystaline structure formed when quenching. The surface hardness and therefore brittleness that comes from a quench does not necessarily permeate the entire blade, for example when you send gears to be hardened you specify a hardness, usually in the rockwell scale and a depth of hardening, this is the depth to which this hardness if assured - and beyond this the steel regains its more natural properties the deeper you go, heat is not conducted at the same speed in the core of a blade as the outer Now when I was referring to the structure, I was not meaning the misalignment hardening of working a blade, this would weaken a blade noticably, this can be remedied by a process of heat normalization also known as tempering as you will know, this will allow the blade to return the interior structure to what it was to some extent, however you have to some small degree "Stiffened" the horizontal of the blade making it more resistant to bending, but more prone to breaking, if struck hard on the side on the blade So we have this order of operation Heat billet Work material - work hardening occurs Heat to anneal Final blade shaping work hardening occurs again Normalise/ Temper - undoing the work hardening to return ductility Quench - Rapid temperature change hardens the surface and roughly 0.010" to 0.040" (0.25mm to 1mm for the metric minded depending on the manner of quench, and core ductility is maintained Now the point I was making is this, Stress fractures always occur at 90 degrees to a stress raiser. In tiles this means a line scratched in the surface will become the line of breakage In swords this means a blade impact chip will become a focus of weakness and over extended usage will eventually become the point where a blade would snap. When you strike with the tip of a blade the front of the blade is in tension, the rear is compressed: you don't see this as, as you point out blades are usually strong in this manner. however if a blade has been hardened, and there is a chip in the blade the blade may be brittle to the point of snapping at the chip, just like the tile would break at the scratch, because it has reduced ductility The fuller as you pointer out tends to spread the extruded mass along the main beam of the blade, Now if the sword was as base 2mm thich, and the hardening was 0.5mm thick on each wall that ductile core is only 1mm thick. However if the blade was thickened on the beam, by just 0.25mm by the extruded material from the blades neutral point, it is now 2.25mm - 0.5 from each wall, the ductile core is now 1.25mm thick meaning the volume of ductile metal has increased by a quarter from a blade thickening of 1/8th. Now due to the width of the ductile metal increasing slightly, and the fact that this ductility thickening is further out from the neutral point of compression/tension, this sword is FAR less likely to snap in a hard combat situation where you have damaged your blade, either through parries or striking steel rimmed shields and then plant a heavy strike on an opponent, for example if you have removed an oponents shield then reversed your sword to deliver a murder-stroke.

[@bengrogan9710]

+Ben Grogan Also with regards the "Ridges" on some fullers, they require some work as to work those you really need some way to locally heat the core of the blades flanks without heating the blades edges where physics dictates it would naturally gather

[@shadiversity]

+Ben Grogan Hey this is a really great point, especially for harder steel swords. I suspect you might be right and I'm going to think about it some more. Who knows, a part three might be needed ^_^

[@bengrogan9710]

I am Shad This also goes a little way to explain Double Fullers, where they where likely trying to maintain a central beam of ductile metal as cracking from a heavy side blow to a wide fullered sword, that didn't entirely break the blade requires completely reforging the blade It also goes a long way to explain why so many Fullers are only roughly 1/2 to 2/3rds the blade length, as snapping of the tip of the blade is a significant hit to your reach but you would still have a semi effective weapon midfight

[@WalkaCrookedLine]

+Ben Grogan great explanation.

[@Beamer1969]

When hardening a sword you are only hardening the surface, the fuller gives you more total surface area to harden. I think that would change the strength of the blade but I don’t know what the effect would be.

[@TheTriumphbsa]

Perhaps we should look at how the sword was used. In respect to the Fuller, one often takes an offensive strike on the flat of the blade. Obviously more surface area to block with. On common swords made for general use in an army of Middle Ages ( insert your favorite old millennium here where swords were a main battle weapon of soldiers trained for it), swords were not the best quality. Number over quality. Would that not lead to poorer quality steel and forging? Knock em’ out, stretch the purse, lots more vs less, but better weapons? Perhaps the rigidity of such common blades needed the fuller to add some spring so they had a better chance of not snapping when using the flat against a heavy downward cut? Sure perhaps better and best quality swords that took great time and care did not need them so much, and the aesthetics of a fuller was a more prominent reason for it. But forging 500 swords by the spring fighting season by a couple of blacksmiths? Stiff and lower quality weapons not quenched slowly or properly because of money And time and amount and lack of that spring demands a fuller to compensate. I guess?

[@ARR0WMANC3R]

I hope this becomes a full series from you... It would be delightFull. I think it would really strengthen your (blood) channel... It could really get you into the groove of things.

[@ShockNAwww]

Bah....

[@Gnurklesquimp]

A full series would be quite the grind though. But indeed, it could help his channel forge ahea... I'm going to stop while the potential brain damage I've caused is still minimal

[@hitmanmtg8615]

HaHaHaHaHaHaHahaHaHaHaHaHaHaHaHaHaHaHaHa!!!!!!!

[@thomashamilton9296]

I’m an engineer who does understand the rather involved math that you would use to calculate the strength of a sword. I have to say that you have a superb understanding of the subject. Every time I had an objection to one of your statements, you addressed it in the very next statement. Very well done, sir. I would have liked you to broaden the discussion to include the effect of thickness on cutting (a ridge increases strength but also thickness, which is bad for cutting). Also, that adding width also increases broad side strength by virtue of the added material rather than added distance to the neutral plane. I am one who enjoys solving design problems with multiple dimensional, and I can tell that you are too. Thank you for being so thorough and precise, I would have assumed that you were an engineer if you had not said otherwise.

[@Xiras1985]

Not fully correct on the quenching part. Heating it up and quenching it will not remove all the structural stress you spoke about. In fact, if the blade is too stressed, it will be more prone to bend when quenched! That's why the steel often is normalised before quenching. Also, how the steel forms when you forge the fuller in, it depends on heat distribution, steel alloy, forged on a flat anvil vs. a counterparted tool etc

[@jonathanguitard984]

An important point to think about with the forged fuller is that while you are not necessarily gaining any inherent strength, you are also not losing any. What the groove does is to increase the surface area without increasing the actual width of the sword along its flat. The actual distance between the peaks of the fuller is longer than it would be if it were flat, so there is an increase in surface area. And an increase in surface increases strength, which can offset the loss of strength from thinning the blade with a fuller. So a properly created fuller wont inherently strengthen the blade, but it also wont weaken it. So the Concept could be to make a lighter blade without makingthe blade weaker

[@1983pety]

I think that forging is better for the same reason they usually forge crankshafts, so that the fiber flow on the outside of the blade stays intact. So if you take two identical blades, one with ground fuller and one with forged fuller the forged one will be more resistant to stresses.

[@dysturbed1]

Actually Normalizing (heating and letting air cool) makes the grain structure to a similar size thus making a more consistent metal. The quench changes the molecular structure. You had that part right. The temper softens the quenched steel and makes the steel less brittle so it does not snap or shatter.

[@saskprotogencyus2788]

This is actually a very similar principle to the hollow driveshafts that they use on rear wheel drive cars, where having the shaft have a larger outer diameter but be hollow inside allows them to build a driveshaft that is just as strong but is lighter weight overall.

[@RJ-vb7gh]

Although I've never tried it myself, I had a discussion with a German WWII veteran and survivor of a few years on the Russian Front who had a lot of personal experience with bayonet and knife combat. He explained to me that the reason bayonets have "blood gutters" is to make them easier to extract from the opponent. He claimed that a wide flat blade "gets stuck" in the opponent during a piercing attack and is very difficult to withdraw especially if it goes in deep. A fullered blade or a bayonet with a blood gutter withdraws much more easily. And in combat puncturing your opponent is only half the "battle". Getting your blade back quickly and easily, so you can use it again, is almost just as important. So yes, you might sacrifice some strength with the fuller or blood gutter, but you reduce the time and effort required before you can make another strike or stab... When I asked him why a fullered blade would be easier to withdraw, he explained that he felt as if the body of the opponent somehow sucked onto the blade with more than just friction. He felt that the opponent's beating heart caused a vacuum in the tissue that didn't want to let the blade go. In any event, he's long deceased now, so he can't add to the discussion... but stabbing swords and bayonets from all over the world have fullers and blood gutters and that's the reason they are there.... Do they just reduce friction going in and coming out or do they break the vacuum from the opponent's beating heart, or both? I can't say, but a " slightly weaker" blade you can stab with repetitively strikes me as more useful than a "stronger" blade you can't get out of your first opponent, especially if he isn't completely incapacitated (and presumably agitated by being stabbed) or if you are in a combat situation and there are other opponents who might not be willing to wait while you (and your friends) extract and recover your blade from their fallen comrade before resuming the fight..

[@DeathsHood]

I'd be interested to figure out how much metal is actually removed in your standard fuller, weight wise.

[@BenMBass]

When you forge a piece of steel, some of it literally rusts away, put a piece of steel in the fire and work it, and after you're done it'll be a bit lighter

[@TheCrimsonIdol987]

To get the ridges along the fuller, wouldn't it be easier to do a hollow grind instead of a flat grind to get the ridges on the fuller?

[@bowtie3776]

also, the quenching doesn't effect the crystals, thermocycling does, which is just heating it and then cooling it. the quench itself then sets those crystals, so to have the most even crystalline structure, you would want to heat it, cool it slowly, then heat it and immediately quench. if you don't thermocycle, it will actually be harder, but it will be significantly more brittle.

[@AlanHearshel]

Hey Shad, Not sure if you still read comments on older videos like this, but I have a question that I would like you to review. You said that the fuller can weaken the blad in the flat plain... but the sword wielder would never swing/use the blade in that angle, right? I mean, they would most likely always swing in direction of the edges, so, unless they want to "slap" their foes with it, I believe that that weaking of the flat plain would not be detrimental to the usage. Can you comment on that? Also, another question: I heard somewhere else (cant remember where) that the fuller are necessary so the blade doesnt stuck on its target. Supposely, it would make air to be drawn inside the cut and help the wielder to pull the blade of. Do you think that is possible? Anyways, thank you for the great videos, and keep up the good work! (sorry for any english mistake, btw, im not fully fluent yet hahah)

[@tedarcher9120]

Swords don't stick in meat, they get stuck in bone, and fuller doesn't help with that

[@MrMaxBoivin]

One thing to consider if you are to forge or grind a fuller is the time and energy required to do so. Nowadays, with power tools it's usually easier and faster to grind but, it might have been different in medieval time...

[@stoneslash]

I would argue that the quench would actually harden the thinner steel more thoroughly and would temper more evenly. giving a greater chance of a proper spring temper on the sword as a whole. That would be the real reason to put them in. It makes the heat treating of the entire weapon more likely to work in a basic workshop. also it helps to keep warping of the blade as the stresses of quenching are applied to a minimum. also curving the plane does make it longer. and should almost completely negate any thinning of the blade if not cut too deep. so honestly' no loss of structural rigidity should occur.

[@NeverWolf]

Hello Shad. I think I know of a potential benefit of having a fuller although I don't know that this is the reason for having them. You know when you blow on a somewhat empty water bottle and it produces a tone? You can't just blow into the bottle to produce the tone, the air must be traveling almost perpendicular to that bottles choke. A similar thing happens with the fuller of a sword when you swing the sword and the edge is aligned properly. Air going past the edge travels perpendicular to the fuller, producing a swishy sound. Sometimes and it varies from sword to sword, there is a sound that it makes when you know your alignment is just right. So it provides an audible indicator of edge alignment. This isn't as important in a fight as it is when you practice handling the sword, the sound provides important information as to how well aligned your cuts are without having to cut anything and wear out the sword.

[@Uncephalized]

If anyone says you will compress steel by hammering on it, you can gently tell them they are wrong. Steel is incompressible. The steel under the hammer does not become more dense. It flows away from the hammer like a liquid. It just moves to a different place.

[@Zedlolmyster]

a thing about ridges around the fuller is that doing so would (probably) negatively impact the cutting ability of the sword. things like pipeback sabers and such are a bit notorious for this and it would be kind of pointless to put a fuller in only to reduce cutting effectiveness.

[@PsylomeAlpha]

In my experience hollow grinds cut amazingly well. It is implied that you would be taking some of the blade's thickness and moving it back towards the spine to do this, so the cutting performance might actually be increased while simultaneously retaining thrusting ability to a superior extent when compared to a fuller without the ridges.

[@sirprisinglynot3549]

Oh, yessss. Thank you for getting the metallurgic part right, people online tend just to scream random pseudoscientific nonsense while even my metallurgy Professor from Uni would probably approve this. And I agree fullers are there because of the weight-stiffness trade off along the edges with a little loss in flat rigidity; this is wonderful for cutting while, as renaissance guys knew, diamond section was the best option for thrusting stiffness (like those pointy misericordia daggers)

[@Runoratsu]

At first glance I think fullers (in this case a fullered sword vs one of the same mass w/o a fuller) might also strengthen the torsional rigidity of the blade, which might be even more important than the rigidity along the flat side for cuts, so that the blade stays at the correct angle, because for torsional rigidity, the lines of greatest force would run diagonal between the outermost points, so the material between those-in essence, where the fuller is-wouldn't carry a lot of force anyways. Haven't calculated it yet, though, it's just a gut feeling.

[@lioncrusader4447]

Sir Shad I know you always do your complete research to the fullest and you put a lot of thought into these videos. I respect that. That's why I'm watching, but on this subject I will have to disagree. You are missing another basic principle of engineering. When you have surfaces with different angles they are harder to bend. Why you think the manufacturers press grooves in sheet metal in the production of so many things: guns, cars, caravans, lockers, toasters, etc. To make them stronger. I know swords have nothing to do with sheet metal and with fullers you're actually eliminating material but the same principle still applies. Hexagonal vs broad fuller- maybe, but lenticular vs lenticular with fuller or double fuller I don't feel like we're giving up anything in rigidity. There is only one way to make certain about it. find two equal swords one with fuller and one without press their tips against a tree and start bending them. I'm pretty sure they will behave exactly the same only the fullered one will be lighter. One more thing bloodgroovebloodgroovebloodgroovebloodgroovebloodgroove.............

[@elijahoconnell]

If something is at an angle it increases the distance from point a to point b, swords with fullers have a greater angel (the angel from each side of the middle where the fuller would be) therefore increasing surface area

[@alexandrumoise1511]

moreover, that compression point is irrelevant if the sword is to be heat treated, because every tension built up in the sword is going to be released in the austenitic phase, when the sword is heated. Same goes for grinding: if heat treating is done afterwords then any kind of continuity property in the material is renewed when the granules of steel recrystallize.

[@diarmuidbalfe7264]

history proved your points because more thrust-centric swords there is often no fuller and a central ridge down the middle.

[@shepardw4981]

Yeah the Roman Gladius is dual edged and has that Central Ridge on either side in the middle

[@gman1515]

a fuller can also be used to fine tune weight distribution. And I've studied some on the subject of these compression and tension forces for bowyering. the answer is Yes, the ridges can make up for the lost strength while still leaving the weight reduced. BUT, they would be fairy tall and thin. they would be terrible for the cutting profile and prone to breaking as the sword hacked into a target. and honestly, the detriment isn't always a very large one anyway. a significant amount of weight can be removed while leaving enough of the blades original profile that the strength is effectively the same anyway, but a few millimeters too wide and that begins to change exponentially as the blade becomes weaker. and that would vary a lot with the different dimensions of each sword. so putting a fuller in and finding that perfect balance would be a near impossible task. that's why a bladesmith who could do so would likely be hailed as a master of the craft. that's my thoughts on the subject

[@SkunkworksProps]

Based on my experience of grinding fullers in, you'd have to make between 6-10 swords before the amount of steel ground out for a fuller would amount to a new sword (depending on sword, depth of fullers etc). Worth it these days? No. Worth it back in the 9th century? Probably.

[@tedarcher9120]

10-15% weight reduction is no joke

[@bowtie3776]

personally, I think the ultimate would be to make 2 fullers, forcing the material in as well as down, creating a ridge in the center that is higher than the original blade, with the material for that ridge removed from either side of it, bun not removed from the very edge. this sword would be the same weight, same width, and have the same edge profile, but would be trading a little bit of it's edge on rigidity for side on. this loss could be counterbalanced if some of the material went outward, but the side on rigidity would be much better, and the edge on rigidity would still be fairly high. whatever you do, though, to make a blade stronger edge on you have to increase it's thickness, and the only way to do this without adding weight is to start with the blade thicker, and reduce it's thickness either by making it the width you want but extra thick and grinding out a fuller of some kind, or making it skinnier but extra thick with the same amount of material, and getting the width you want by forging in a fuller, thusly spreading it to the desired width. the net effect is the same, with the ground fuller being more energy efficient, if you have a grinder, and the forged fuller being more material efficient either way. TLDR: rigidity comes from material further out in the direction the pressure is applied in, and a fuller can make a blade stronger by moving that material further away from the center. How you achieve this profile doesn't matter, only the end result.

[@illoney5663]

Also, by making those ridges you will make the sword less streamlined which will lessen its cutting capacity.

[@tomlambert1545]

in my experience with swords and making swords is that a fuller-less sword is made for slicing and a sword with a fuller would be used for both slicing and plunging a fuller is extensively there to stop suction when removing the weapon from an opponent so forged or ground it doesn't really matter

[@clintcarpentier2424]

Simple and relatively cheap test for someone with the means to do so... Materials: 3 - 3' steel bars, 2" by 1/4" Weight scale Hammer and anvil Grinding wheel Forge Quenching apparatus Plan: Weigh the bars, be sure they start identical Take first bar, set it aside as the "whole" bar Take second bar, and forge a fuller in, minimum of 1/2" wide, to a thickness of 1/8" Take third bar, and grind in an identical fuller as the second bar Weigh the bars Heat treat all bars Weigh the bars Test the abuse level each bar can handle Conclusion: Should the fuller prove less resistant than the whole bar, then blade strength can be removed from the argument. Should one fuller be stronger than the other, then method strength will be determined. No shame in just sexiness.

[@xrexc3179]

Actually normalizing the blade is what equalizes the stress within the blade and this done prior to quenching and after the forging. The quench doesn't equalize anything. If you quench without normalizing you almost certainly warp or break the blade. Historically fuller's were used to affect the balance of the weapon. After forging if a blade was not "lively" at least for that point of production a fuller was added. After all you can always remove material. Adding material to a blade that has ended up too weak or improperly balanced is not so simple. However most often a forged fuller's does not lighten a blade either for the material is still contained within the blade. It's simply packed more densely. By fullering the material is redistributed thereby affecting the balance, sometimes dramatically

[@colsoncustoms8994]

You actually normalize the blade before the quench. That is how you relieve the stresses built up from forging.

[@stephend50]

maybe we're thinking about this wrong. maybe the fuller is effectively ADDING material, thickening the blade, for a given distal taper, to make it stronger.

[@Daonitre]

in regards to the forging process where the hammering would push the material out more uniformly, I would agree with the exception of variable metal swords. While they are more of a recent thing in the long history of swords and forging, wouldn't having the "softer" metal as the core and a "harder" metal edging vause more of the first picture where the fuller would have the lifted ridges? Mostly devils advocate here -- I totally agree on pretty much everything, I just don't feel that you can have this conversation without acknowledging that swords are made of different (and in this case multiple) metals.

[@AndrewJordanBladesmith]

Hello Shad . I’m the person holding the Great sword in your first picture on your Video “ Forged or ground “ You are correct regarding function between Forged fuller or ground . You missed the fact I have made two Great sword based on the London Museum Found at Temple bar which has been attributed to the Knights Templar . The first one was a forged Fuller as per the Katana article from 2004 [ unfortunately now not printed ] Where my process was explained . I would like to say that your conversation regarding the difference between Forged Fuller or scraped or if you want stock removal are absolutely correct . The assumptions of Cyber commando are irrelevant when compared to metallurgical data ….. I’m fed up with the attacks I get because one of my Great swords was Scrapped into the Bloom steel blade , where as the First W2 blades was Forged in . [ As per the Katana Aprile 2004 article . I’m also fed up that anything I’ve said regarding my experienced in the past 40 years of my research in sword and knife design are set upon by known Smiths with backing from a CNC machined production basis . I met this person at Solingen when I returned from Japan . WE met at the KIINGER Museum . I spoke to this now GURU about my research and we found that we had much in the same way of thinking . Regarding the forging of the European sword . I know from other smiths that This person has gone out of his way to poop poop anything I have said or written as not relevent on the subject I have researched in depth . It would be nice to talk with you on a video allowing my point of view to be placed in front of a General public I have been denied real access too because of my beliefs . This use of age old principles of design such as in the VP [ Vesica Piscis ] is clearly apparent through out ART history and is evident in structure such as the Parthenon and in Chartres cathedral outside Paris . Where there is a Carving in stone above the main entrance gate of Charters showing a carving of Jesus with what looks like a vertical almond shape , this shape is the inner part of the Vesica Piscis . The use of which is not owned by one person . AND if you understand art history you can see it through out it’s entirety . The person backed by Albion CNC swords has no right in hijacking his hypothesis and making it seem he is the sole inventor of the use of VP in structured design balance in swords . The use of VP is a natural thing for good craftsman of all types to use for better design output . This happened in Charters cathedral the first cathedral built in the medieval period . If you ever would like to interview me on my work and my connection to this great craft of Blade smithing I would be very pleased to give you a interview where I can talk with you in detail about my life long struggle with forced censorship by my so called community of bladesmiths Globaly . Having a Degree in Industeal design , A Master Archtectural modelmaker and protype modelmaker and a 3rd Generation Bladesmith . ! I remain in hope that what I have written above will fall on ears that listen and think . Your Video is correct in it’s hypothesis ….. Maybe you might want to contact me for a short talk about a interview on your channel . ??? I hope so . The time is right . But I'm very late in my reply .

[@shepardw4981]

What about a way of making the sword more balanced. A lot of Swords the Fuller only went half way . While others went all the way or had even three Fullers with some kind of combination. The kind of swords that Fuller's were traditionally put on were very long and unwieldy. so to make it more balanced from tip to handle and lessen weight would be a benefit for a multi-purpose sword that chops as well as stabs.

[@Roland3ld]

Thanks for the info, I didn't know fullers could be ground out. I only ever thought of them as being forged.

[@dacianbonta2840]

For the same total cross section (thus weight per unit length), having a fuller moves material away from the center in both direction, both in short transverse axis and long transverse axis. So, it should increase the rigidity of the blade for the same weight.

[@1truckingsmith]

Still not answered: is the force redistribution away from the blade spine, during a proper perry. I think it would be an interesting experiment to put a fuller on a bow. Edit: additionally remember the principle of the arch

[@PsylomeAlpha]

Perhaps you could design the fuller die to imprint the ridges while forging the fuller?

[@aussiebloke609]

Considering the potential for forging a fuller that isn't perfectly straight or of uniform depth...and the time-consuming mess and wear on grindstones if it's ground into a flat blade...it makes me wonder if most fullers were forged in originally, then ground to remove imperfection, straighten them, and generally tidy up the blade before the final polish?

[@TheGenericavatar]

I would think both forging and grinding sword fullers would be used on the same blade to speed construction up. Forging the fuller could greatly reduce how much time is spend grinding the rest of the fuller out.

[@jnix6996]

It's all about suction when you stick something into a body you create a suction with the Fuller there by slightly twisting the sword breaking the suction the blade can release

[@EitriBrokkr]

a drawn out bar of steel has a grain structure to it. if it was a "every which direction crystalline structure" it would be cast iron and shatter on impact. picture it as piece of wood with grain. stock removal will always be weaker than forgings. forgings realign the grain structure. that's why high performance everything (engine parts, hydraulic fittings, bearings, crane hooks, blablabla) is forged. side note to that with modern manufacturing, material stock removal is faster and cheaper, they forge things because they're stronger. However in medieval times forging fullers would have been cheaper and faster. grinding fullers would require a secondary operation, additional equipment, some additional power source to turn it. where while the swords red hot anyway, you can just bang them in there.

[@Tectonix26]

I was told it was a way of stopping the sword getting stuck by stopping the vacuum made when someone is impaling, but given how rarely people were impaled I'm beginning to doubt that notion.

[@Eoraph]

A fuller can also change a blades balance significantly. I guess some fullers were solely put onto a blade to give a certain sword geometry the right balance.

[@thisisnotanick]

I could imagine a situation where a smith would have limited steel to make a sword from. A documentary called "Secrets of the Samurai Sword", you can find it on KZbin, shows the process of smelting the steel used in katana swords. Its really interesting!

[@wyattroncin941]

thisisnotanick sure, it might be interesting, but the swordsmith knows exactly how much steel he needs, and would only make that much if he only intends to make a single sword. However, Japan was already short on metal, meaning they didn't have the steel to make things like nails and all their construction methods are entirely wooden, without any nails. In europe, a blacksmith would get up at dawn and be making nails until dusk unless they are dealing with a customer.they didn't have to worry about steel shortages. Japan was different, and they would only smelt the steel needed for one blade at a time.

[@thisisnotanick]

My point was that not all the steel you get out of a furnace is good for swordmaking. Some parts get too much carbon and some parts does not get enough, so a smith would have to be picky about the steel he uses to make swords.

[@NobodyDungeons]

Actually, I think the forging in the fuller would make the sword a bit less rigid because if the softer steel gets pushed out of the way, and into the other areas of the sword then you'd end up with weaker steel on the edges of the sword which is exactly what I would not want as you generally want the edges of the sword to be harder and the core to be softer if I am correct in my knowledge

[@manuelvanloon2730]

Imagine the cristaline steel structure as a net - grounding down the fuller is like taking out parts of the net wich is clearly weakwning the full structure. Instead the forged or hammered fuller remains the net entirly

[@DavidGonzalez-so1eb]

Absolutely fantastic video M8! I have absolutely nothing to add, in fact I've even learn more with this two videos that what I know from before. Thanks

[@hotsteamypudding]

So there were a kind of british sword called a pipebacked sword (sabre) where they literally attach a pipe that is thicker than the blade to the back of the blade and the basic problem - when you are talking about ridges etc - is that they basically reduce how well the sword cuts (and this is why people stopped using pipe-backed swords) - the edge of the blade goes into the target material but then the target material hits this bump/step in the blades geometry and that basically acts like a road speed bump and adds restistance to the cut (in some cases apparently the cut just sort of stops) - which then immediately leads to questions about why you bothered to have a shallow blade geometry if you were then, an inch/half-inch from the edge going to suddenly increase the thickness of the blade - I do wonder if something like that could be done well though, if you have an especially wide single edged blade maybe enough of the blade would enter the target material - say 2 inches - that it just didnt really matter because the target material had been cut enough already (british sabres didnt have particularly wide blades so this wouldnt have been seen on a pipe-back sword). Interesting idea.

[@jasonspade203]

My guess, well Actually from eperiance I figure that the fuller is for reducing the drag or friction of the blade during a cut rather than strengthing the blade. However I do agree that it helps with weight.

[@blakewinter1657]

I'm genuinely curious about the relative strengths of different cross-section shapes vs. their areas now. I will try to run through some very rough computations at some point soon and try to get a general idea. However, it is a very complicated question, because it really depends upon how the steel reacts to different levels of compression and tension (it will never be an ideal spring). And that kind of materials science is something about which I know nothing. However, I may be able to get some general idea under very simplified assumptions. EDIT: Under some great simplifications, we can say the following: for a fixed quantity of material, and a fixed length and width, then cutting out material from the centre and putting it as 'peaks' will result in a shape which, under bending, will stretch and compress the material _more_ than if we left it a uniform thickness. This means that a sword made of a uniform thickness would tend to be a bit easier to bend. So, if you want a stiffer sword with the same dimensions and weight, you want to go with the peaks around a fuller, and not with a uniform thickness. At least, that is my conclusion so far. Note that this does not necessarily mean that the sword would be able to withstand more torque. It just means that for a fixed amount of torque, the fuller-ed version will take on a shallower curve than the uniform version. As to how much torque could be applied before breaking... I'm honestly not sure.

[@himanshuwilhelm5534]

What happens if you quench metal in the presence of a large magnetic field?

[@zfrenchy1716]

the fuller on a sword is there to balance the sword preciselly to the porter felling of the sword.

[@SirGalath]

I would love to see a part 3 dedicated to fullers and cutting. Does the weight reduction and mass redistribution of a fullered blade produce a better cutting sword than the higher stiffness and higher weight of an unfullered one?

[@brokenursa9986]

+Sir Galahad I'm not the most experienced person on the subject, but to my knowledge the balance of the sword is affected more by the amount of material in the hilt, the pommel especially, than it is by the material in the blade. As for the mass, a lighter sword is usually easier to handle, but a heavier sword generally strikes harder. However, the handling and striking power can be affected by balance as much as they can weight, probably even more so.

[@SirGalath]

Ryan Cauffman I agree that a pommel has a higher impact on balance than the blade but my question still stands...

[@thewolvesbane2536]

+Ryan Cauffman Whilst that is true for a lot of swords, and pommels are almost always used for giving the balance it's final tuning, on most historical swords the bulk of the balancing would be achieved through distal taper. Distal taper of course being the (often) gradual change of a blades thickness from the base of the blade to the point. E.g. a blade starts out with a thickness of 7,5mm and thins out to a thickness of 2.5mm behind the point. That is done because it results in a more lively blade, with more mass in the blade, which aids in cutting. Also in my experience, swords that have a nice point of balance but are balanced exclusively through the pommel, feel really awkward in the hand. Also distal taper allows you to make really long blades, without needing a huge amount of counterweight in the pommel. If you look at some Zweihänder, you'll notice them having really small pommels, yet they still seem to have a good balance (or at least all of those which I have seen the data on the PoB, seemed to always have it close to the guard.) Also making huge big Falchions like the one Matt Easton has (look at his last videos, you'll understand which one I mean) would not be possible without distal taper, because they would be to heavy and unwieldy for usage. With distal taper on the other hand, you get a huge big cleaver, with the weight of a mere Rapier. Another great example for the necessity and effectiveness of distal taper for good balance are 19th century military sabers. They of course lack any pommel whatsoever, yet on the same time are really well balanced, due to massive distal taper of often 9-10mm thickness at the hilt and only 3mm at the point. This list of historical examples could go on and on, but I think you get the point.

[@PhilBagels]

I wonder if there is a Fuller brush you can use to clean a sword.

[@foxofss]

The argument i have heard, is that grinding in a fuller weakens the structural integrity when compared to a blade that wasn't gouged to create its fullers (forged in). The folk talk is that something about the process of grinding holistically weakens the structure!?

[@kunichuck]

Please make a video on tempering, quenching and metal properties :)

[@soulpanda5616]

I can see how forging fullers might have a materials savings in a factory where many craftsmen are working together and you can get an economy of scale. I mean, as an example these are not real numbers, if you have to make 100 forged fullers to save enough material for another sword, a lone smith would only save 3 a year if they make a sword/day, while a factory of 10 craftsmen would save enough for 36 at the same rate of production. I honestly don't know what a medieval swords factory would look like, but it is the added efficiencies possible with economy of scale that makes people band together like this in the first place.

[@nicolaiveliki1409]

I'd personally prefer a diamond crossection over a fuller. Though I do believe that the decision whether to forge or grind a fuller is mainly economical. You wouldn't want to waste Wootz steel, arguably the best steel available to human kind until the 17th century, which you've bought from your favorite steel importer from Tamil Nadu in southeastern India at 20 Guldens per pound, by grinding a fuller. On the other hand regular steel from the local steel mill... Forging a fuller is just so extremely time consuming and takes quite a degree of mastery to perform compared to just having the apprentice grind it out...

[@answeris4217]

To me Fullers give an a chance for the forger to balance the blade. To distribute the weight to where it needs to be in order for the Sword to preform better. Kind of like adding weight to the wheel of a car or drilling holes in Armatures and anything that spins. It also strengthens the idea of the fullers being grounded in after the sword is finished to a workable product. If it would be simple to make things that are perfectly balanced we would know how to do it by now and it's not close to being the case.

[@milleniumtardis]

A bit late to this video but I wonder if a fuller would make the sword less wind resistant. Like how golf balls have dimples. Would it make it easier to swing?

[@jdr9942]

Ma6 not mean much. But I make viking age Reenactment swords. I get blade shape forged and quenched and tempered. Then I grind in fuller. Tempering with a fuller already in can over temper the fuller area before the edges get tempered. That can cause a blade to bend and not come back. From my experience. Not saying I'm correct, but I imagine if the entire blade is tempered same thickness. Then fuller ground in, keeping it cool to not mess with temper, the fuller and edge will be the same. I feel, astronger sword.

[@reddokkfheg9443]

Another nice video. As i am been saying the same thing. or basicly the same thing i am glad someone did a video and explained it and as usual i did learn more about it from your video And about the ridges. i dind use the pic you showed about how to make the fuller during forging. But i agree that just by creatign a fuller you wont get those pronounced ridges it would be more spread out and make the blade wider to at same time as it made it slightly thicker in the areasbetweent he fullers and the edges That added thickness and added weight will make it a little stiffer. but the fuller itself will weaken it as it is thinner there. Will the increased thickness and weight strenghten the blade as much as the fuller weakens it? i don't know, probably not unless you manage to ger farily pronounced ridges then maybe. but even in that case its not the fuller that makes the sword stiffer, its the ridges. But to sum it up i cant see ANY situation where the fuller itself can in any way strengthen the blade. The creation of a fuller if it would increase the thickness around the fuller enough could make it stronger. but then it would be the increased thickness that made it stiffed not the fuller itself You could maybe argue that it is the the process of making the fuller that increased the thickness around of the blade on the side. so that the creation of the fuller did actually make it stiffer. But if its like that its still not the fuller itself that made the blade stiffer. only the results the process of making it has on the other parts of the blade

[@dwightehowell8179]

Actually forging a sword fuller does make the sword wider and stronger edge on. It should also cause a slight build up that might make it stronger side to side. Removing metal isn't going to do either. I'd guess that the fuller's main purpose is to make the blade lighter and faster. Who ever lands the first solid hit can often pound their opponent down.

[@Roland3ld]

So, is this video a debate about fuller emptying?

[@LCO213]

Would forging the fuller reduce the swords weight? If you're not removing any material, how could it reduce the swords weight?

[@MusikCassette]

When the matiral, that was in the the fuller all ends up in the ridges, you would have a net win in strength. by the way, you say, that the however I do not think, that this is what fullers were made for. I suspect, that they were used in forging proses for the fine tuning of some qualaties. Noticible the balancing and the nodes of resonance. You can move the point of blance nearer to the handle by cutting part of your fuller (something you realy do not want to do if you already have the balance you want). A think forging a fuller does something to the stiffness of the sword. But it is little. So it can be used, to move the nodes of resonance. You would want to have one on the handle, and perhaps on on the point of percussion.

[@smoshfan99999999]

maybe fullers were put in for when you stab at armor it will be less likely for the blade to snap

[@robertgiggie6366]

there is one thing I want to point out, by adding a fuller you are actually INCREASING the surface area of the blade look at the cross section and measure it.

[@christominello]

Robert Giggie I laughed when he said that in the video.

[@JakeMcNaughton]

I forge blades and know a little bit about metallurgy, so i have a little to add without actually contradicting your thesis. I would say the compression and "crystalline structure" arguments are the same. Whereas heat treating does regulate the size and type of the crystals they do tend to arrange themselves in rows forming a sort of "grain". i would suspect that this would be more pronounced in historical inconsistent steel or pattern welded steel. So forging would compress the "grain" rather than cutting it off by grinding. As such forging vs grinding would be similar to the strength difference between bending wood to shape vs. cutting but since the "grain" effect is so slight (nothing like wood for instance) this really doesn't make much of a difference which is why stock removal blades are so common; they just don't work /that/ much worse. Also, without doing any math or anything intuition would suggest this strength is in the direction of the edge and wouldn't really be a noticeable difference the way it is in forged vs. ground edges (similar to your comment that this "compression" would help more at the extremities). But, to be honest, forging a fuller is a hell of a lot easier and quicker than grinding so I don't know why anyone would grind a fuller. And some of the larger fullers probably save enough metal to make a small-medium hidden tang utility knife which isn't inconsiderable. I would guess this was a bigger motivation in the large viking-era fullers. While iron may be plentiful across Europe, it was slightly more rare in Scandinavia and it's work intensive to get to a usable state.

[@KuLaydMahn]

My understanding was that the blade is "stronger" *BECAUSE* it has more flex. I understand where that is a problem if your steel is so weak that it's easy to bend and doesn't correct itself, but for steel that is more difficult to bend in the first place, and especially in spring steel since it springs back into place, having a flexible blade decreases the likelihood of having a snapped blade. It's common martial philosophy: the bending break long after the bender has broken. It could just be popular myth but that was ALWAYS the reason I've heard: a fuller increases durability by increasing flexibility.If someone can correct me, *please* do.

[@hilossrt4]

You know how quality chefs knives have holes, slots or such cut into them to help release cut food? I think fullers are there to aid in releasing tissue during the cut. Really who wants fingers stuck to the side of their blade?

[@heroman-cd3be]

Hello shad! Im not an expert in medieval weapons, and i know this video was posted 4 years ago, but isnt the fuller notch supposed to prevent things from creating suction onto the blade? Ive seen this with kitchen knives. They have a very shallow groove on the side of them like a broad fuller.

[@Suprentus]

I could be wrong, but wouldn't a wider blade also naturally be a better cutter? I would guess that a fuller would allow a blade to be wider so that it could cut better without making it heavier. In other words, between 2 swords of equal weight, the one with the fuller would be wider and thus would cut better. This is pure speculation on my part though, but it does make sense to me.

[@shadiversity]

+Suprentus This is something I've had as a consideration for some time now but I'm not willing to make a call on it until I see some practical tests to support it. So yes, you might be right but further investigation is needed ^_^

[@Suprentus]

I am Shad Fair enough. The question stuck with me, though, so I tried looking into it and found this: "The wider and thinner a blade is, the better it will naturally cut (this is why for instance, a meat cleaver cuts so much better than a narrow and thick rapier)." "Wide blades have more mass and have a low cross-sectional profile that produces less friction upon cutting impact. Wider blades are also stiffer by virtue of their surface area. Whereas thicker but narrower blades are also stiff, but with their high profiles produce much more friction when cutting -although are more powerful on penetrating stabs. Swordsmith Paul Champagne explains" www.thearma.org/essays/howacutworks.htm

[@mostlychimp5715]

Love the video. Couple quick engineering comments: around the 8 minute mark you start referring to "strength" when I think you should be saying "stiffness." Subtle distinction, but strength is specifically a property of the material, stiffness takes into account geometry. Also, for the equations & whatnot that you referred to, you'd want to google "moment of inertia." Super minor points for anyone who's not an engineer, but I figured you might find the subtleties interesting. Thanks for the video, cheers!

[@mostlychimp5715]

+mostlychimp Oh I should add I was going to chime in about annealing, quenching, and tempering, but then you did an excellent job covering that! Great work!

[@StridVarge]

Fullers help with not just weight reduction but also point of balance.