Technical question

[ariel]

Virtually all handmade long blades have axial twist: when you hold the blade edge up and look along it's length, it is twisted more or less at least once or, more often, twice. Why is it?
Is it a reliable sign of a handmade blade?
The Japanese blades are as a rule very straight. What was done to control it?

[Rick]

Most of the blades that I have lack any pronounced twist .
The only one I have that shows such a twist is a kris taliseko which is in the Macau exhibition .

I believe that the twist in that blade was put in on purpose to make it easier for the wielder to employ the correct angle of strike that is needed for the effective use of the serpentine blade .

[PUFF]

Many blades often have a degree of twisting after heat treatment. But if the twist 's acceptable (by the smith and the owner), they usually left as is. Japanese smiths have less tolerance for blade twisting and they correct this problem with a couple of special sticks.

[Chris Evans]

Hi ariel,

Originally Posted by ariel

Virtually all handmade long blades have axial twist: when you hold the blade edge up and look along it's length, it is twisted more or less at least once or, more often, twice. Why is it?
Is it a reliable sign of a handmade blade?
The Japanese blades are as a rule very straight. What was done to control it?

I don't know what types of blades you are referring to, but discounting intentional deformation, we have to keep in mind that the thermal stresses imparted by the heat treatment of the blade very often induces some warpage. Thin slender blades being the most readily affected. In fact a considerable amount, if not all, of a Japanese sword blade's curvature is imparted by the quench.

Blades with a softish temper are the easiest to straighten out, a very tricky task at the best of times. Those that are harder are much more difficult to set true.

In my opinion a cutting sword blade that has an axial twist is badly flawed because the load imposed by the cutting will further twits it upon impact. On the other hand, on a short knife or thrusting blade, apart from aesthetic considerations, it is of little consequence. If memory serves me right, I think it was Richard Burton who remarked that it was hard to find a true (un-warped) triangular small sword blade, which as we know are used purely for thrusting.

In short, a flaw free and true blade of the correct temper was very difficult to obtain in olden times and this is why such swords acquired legendary reputations - They were the exception rather than the rule. Quenching cracks and forging flaws were often deemed quite acceptable, if the sword passed the proof test, whatever that may have been. I have a smallsword with some fine hairline quenching cracks in its forte, made by no less than Weyersberg (WKC) and also a Brit officers sabre with some quite substantial forging seams in its foible, yet sporting the proof mark. Both swords function as intended despite their imperfections (I tested them).

With modern steels, it is no longer necessary to impose a severe water quench to harden the blade and as a consequence warpage is minimal if at all present. But in the old days, they did not have the high alloy steels that make this possible.

Cheers
Chris

[Ian]

Originally Posted by PUFF

Japanese smiths have less tolerance for blade twisting and they correct this problem with a couple of special sticks.

PUFF:

Can you elaborate on this method? What were the special sticks and how were they used?

Ian.

[Mark]

Twisting is very common in dha & daab. Its pretty hard to say whether it is "original" or a later deformation from use or mistreatment.

[athena]

In long blade, twisting is common. And the twist may change along with time.

[Jeff Pringle]

It is very easy to get a twist during the forging of a blade, all it requires is not holding the blade, or the hammer, at a uniform angle as you forge over the whole length of the sword. Double-edged swords give you double the chance to make this mistake. Twists also show up in the heat treating, but this is less common than forging them in.
Swords heat treated in the Japanese manner (hard edge, soft back) are remarkably easy to straighten compared to fully quenched (hard all the way through) blades – the trade off is they are also remarkably easy to bend.
Bending forks (which look like this:╒ ) are used to take out twists by placing the blade in a vise at the start of the twist, and applying torque with the blade between the prongs of the fork.
Twists are controlled by careful forging, careful heat treatment, and careful remedial untwisting during the finishing process, but hopefully if you do a good job on the first two, you don’t need the third.

[Battara]

I think it is a good question. I have noticed this also in some dha and Moro kris (not in barong or kampilan however) and some Northern PI matulis. I thought it was something in the forging and/or in the usage. Not sure of the answer myself.