So-Called Harmonic Balance

[Randall Pleasant]

John Clements wrote:
Going around saying that a fabricated blade is more special now becuase it was made with deference to "harmonics" is the kind of thing where we end up with the silliness of naïve folks holding a sword in one hand and going, “MmmHmmm…” as they slap the flat of the blade with the other so they can “check its harmonic vibration” from the wobble.

John

This is so true. Last night I watched another group do some test cutting on mats. One of the better cutters was actually a young boy. Before each cut the young boy did the "pomel slap" thing to find the "spot" on the sword where he should cut. Saddly, he was overlooking what really made his cuts successful - his blade alignment. From where I was sitting I had a good view of each person's blade alignment. Successful cuts had good alignment, bad cuts did not. The young boy received ackownlegement for finding the "spot" but not for using excellent blade alignment.

[John_Clements]

As this has become an interesting thread, I can’t resist.

I can add that as far back as 1863 one noted sword manufacturer wrote succinctly on this often misunderstood aspect of sword cutting, declaring: “Suppose you make a cut at a branch of a tree with the point of the sword, the probability is that your cut will produce very little effect, and you will feel a considerable jar upon your wrist and elbow. The same result will follow if you cut close to the hilt of the sword. In either case you will waste a great deal of force, as is evident from the vibration you perceive in the blade, which represents so much force lost in the cut. If you go on cutting inch by inch along the whole length of the blade, you will at last come to a point where there is no vibration.” ---in other words, the center of percussion for the blade.

Recognized as early as the mid-1600s as being the point on the impacting body that inflicts the greatest impact, the "Centrum percussionis" (or ideal striking area) on most cutting swords tends to be far thinner while the quarter or third of the blade nearest the hilt tends to be thicker. Blades taper in their thickness not just their width and regardless of whether it is an optimal cutting or thrusting weapon, a historical smith often will have forged into the blade from one to three or more noticeable changes in cross-sectional shape in order to produce the best possible weapon. These subtle changes in cross-sectional shape are important because they affect the balance, weight, and action of the sword. Misunderstanding of these variations of mass distribution and their effect on blade balance is why replica swords today so often are not exact reproductions and do not have the same feel or handling properties as the originals. A maker who addresses the issue will likely produce better weapons in that regard...and, hopefully, in the process won't BS the matter to uneducated consumers so they feel their purchase is "special."

So, all this is in my opinion where the now arguably over-hyped notion of harmonic balance and vibration have come from.

Really gotta run now.

JC

[Mike Chidester]

So would the following be considered accurate?

http://en.wikipedia.org/wiki/Center_of_Percussion

[Derek Wassom]

"If you see me holding a sword in my right hand and smacking the pommel with my left, I'm checking blade stiffness"

or for a rattle...

[Brian Hunt]

Hi John,

I noticed this change in the distal taper in all the cutting swords I saw at the Met. The swords were very thick at the cross, generally stayed the same thickness through the ricasso, then distally tapered to about 2/3 of the way down the blade, then flattened out till the tip, and then on some of them, that were also designed for the thrust, the tip then re-thickened.

As for the whole harmonic balance thing, I think that it is the result of a proper blade with well fitted furniture, with a fine balance carefully managed to the design the sword was made for, cutting, thrusting, cutting/thrusting. IMHO, the harmonics will happen on their own with a properly made weapon. Still, it is an interesting discussion.

Kevin, great points. Also, I am still lusting after that beautiful small sword you had at Ashokan. Ahhh, if only I had the money . . . .

Brian Hunt
GFS