And again about kris as examples of a wavy blade
Wavy blade
The wavy blades in stories quite a lot, flambelgue swords, bebutes, kris. There is even a wavy kama in the collection of the Metropolitan Museum of Art. But the most accessible for study and collecting are the Malayan kris, which formed as a type weapons at least a thousand years ago, that is, by now they have acquired fairly stable proportions and design.
Even in the books in Indonesian that the author found, the issue of blade proportions is not raised at all, although I don’t know the language and translated “suspicious” parts of the text with a program.
My interest in wavy blades is quite old, and over the years I have been able to not only look at and measure a number of authentic objects in antique stores and a private collection, but also make a number of blades to confirm my thoughts about the meaning of their shape and geometry.
First, I will propose to distinguish between wavy and jagged (serrated) blades. I consider wavy those in which the bends of the cutting edge are repeated by the bends of the butt and/or central edge for double-sided ones. We call serrated blades (serrated) blades that have a straight spine or a straight middle stiffener for double-sided blades in combination with an indirect cutting edge, as in a number of flamberges of the 14th–15th centuries.
It is impossible to study the real combat capabilities of long wavy blades; they no longer fight with edged weapons, but cutting various materials and objects allows us to draw at least some conclusions. Obviously, the wavy blade combines the light weight of a narrow blade with the infliction of a wide wound.
When fencing, a straight blade is more controllable, the enemy’s weapon with some chance will not slip along the “waves” and, conversely, if the blow falls on armor or a shield, then very small sections of one or several waves will be dull, and the rest of the edge between them will remain sharp. “Running” the cutting edge onto the target material at an angle, as when striking with a shamshir, also makes the cut easier, that is, in a fight it would cause a deeper wound.
An important property is “clinginess” - with a tangential glancing blow, such a blade will more likely catch on an object and cut it, which was tested by oblique blows on various materials, from thick stems of weeds like hogweed to the neck of a turkey destined for slaughter.
In addition, a narrow wavy blade requires less steel, it is easier to carry, and the fighting properties of a wide blade are more expensive and heavier.
Production wavy blades seem more difficult than straight ones, but this is not the case. When forging a knife (stretching) to obtain the slopes of the blade by forging, and not by grinding, it inevitably bends towards the butt. This can be easily corrected by heating it again and hitting the future blade with a mallet, resting the knife with the butt on the anvil. When forming the slopes of a double-edged blade, blows are applied alternately from different sides, but uncontrolled bending of the blade still occurs, and it must be constantly adjusted.
The study of materials about Indonesian blacksmiths and the author’s experiments boil down to the fact that first a long straight blade is forged, and then hot it is bent with a wooden mallet or log on the horn of an anvil, checking with a template or a chalk drawing on the anvil. Therefore, the opinion that a wavy blade is much more difficult to manufacture than a straight blade is not entirely confirmed. Yes, you need a good eye and mastery of the tool to bend the blade where it is planned, and not just anywhere, but it still remains within the skills of an amateur blacksmith who forges one knife not every weekend.
Proportions
The author was most interested in the proportions and dimensions of the blades, in which waviness gives an advantage over a straight blade. Some of the probes were made by metalworking by grinding an already hardened strip, this is how all stainless folding knives of this type were made.
In general, the proportions turned out to be quite simple, although it was not immediately possible to find a pattern. If the wave width is less than one-fourth of the total blade width, then the cutting properties even decrease relative to a straight blade of the same length. The optimal proportions here are a third or two-fifths of the width between the dimensional lines into which the protrusions of the waves fit. The wavelengths should increase by the same amount each, as if in proportion. For some reason, identical waves have worse cutting properties than those that increase proportionally towards the handle.
There are also minimum sizes at which a wavy blade loses its advantage over a straight blade. According to experiments, this difference is approximately 120–130 mm; a shorter wavy blade does not have a noticeable advantage over a straight blade, but it is more difficult to sharpen. The minimum is 120 mm and three waves.
The 90 mm blade with 5 waves did not show itself in any way in experiments. But perhaps there are some other proportion parameters at work there that the author has not found.
The steepness of the waves also obeys a certain pattern, that is, the arrow of the deflection should be equal to approximately one fifth of the distance between the peaks. Smaller values greatly reduce cutting properties, while larger ones require a very peculiar movement when chopping, and are no longer suitable as kitchen ones for cutting food on a board.
In the processed photo below, I drew lines to improve the clarity of the relationship between the geometry elements.
Mythology
Empirically, the author managed dispel some myths.
Myth 1 – when cutting, a wavy blade makes noodles at the edges, which slows down the healing of the wound. Reality - when cutting a wide variety of products, objects and materials, from fresh baked goods and insulation to thick weeds like hogweed, it turned out that the waves make one even cut without any shreds or noodles.
Myth 2 - avoiding obstacles with the tip of the blade. Experiments have not been able to confirm or refute this; the tip of a straight knife can also slip off the obstacle (simulated by gluing a coin or button to an object), or the tip of a wavy one can rest.
Any particular difficulty in making a wavy blade relative to a straight one was also not confirmed.
With the metalworking method of manufacturing from a hardened strip, grinding both straight and wavy blades in any case requires work skills. Manually repolishing the blade with sandpaper on a stick after using an electric file, also known as a narrow 13x457 belt sander, yes, requires great care so as not to cut yourself, but even with a straight blade you can get hurt.
Sharpening, of course, involves a round abrasive rod or sandpaper wrapped around a pencil, and then an extra-fine rod like MKR-95, or similar corundum objects.
The manufacture of sheaths is also generally normal, but they require a wooden or polymer insert. However, even for a straight blade, a pure leather sheath is not entirely safe, for example, if it falls on it in the forest.
Acoustics
The surprise was the acoustic properties.
The trick shown at exhibitions with tapping a sword with a pencil, where the ringing supposedly signifies certain fighting properties, turned out to be strictly the opposite in experiments - a dull blade cuts weeds more easily and participates in the slaughter of farm animals (we managed to agree on conducting experiments with a local livestock breeder) than a ringing blade. The explanation is strictly scientific - the force of the blow does not lead to the swing of the blade with a sound frequency, but only to the destruction of the target.
The idea arises that layered damascus and other welded composite blades were originally invented by observing cutting properties, and not for the sake of beauty or saving metal. On the contrary, forge welding of three to five strips of steel with different carbon contents and alloying additives leads to greater loss of metal into scale than forging from one material.
The author has a suspicion that the existence in Asia of wavy kris and razor-sharpened sabers (and the Japanese katana, in terms of the way it is worn, is a saber, not a saber) is initially associated not with any special aspirations of the masters for the perfection of blades, but, on the contrary, with poor nutrition , frequent hunger and weakness of users - the perfection of damaging properties was supposed to compensate for human weakness. Then, as production and agriculture developed, the hungry years became a thing of the past, but the habit of doing “as before” remained.
I will assume that during the period of their existence, European swords were also sharpened to an extremely accessible sharpness, but over five centuries in damp arsenals, and then only in museums, the thin sharp edge simply rusted and crumbled. It is also possible that servants in the 18th–19th centuries deliberately blunted the swords hanging on the walls of the master's mansions so as not to cut themselves when wiping dust from them.
And this is a mushroom knife designed by my wife; the curves of the blade are very convenient for cutting honey mushrooms.
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