Now I have Hara, what do I do with it?

[Kokoro777]

Its just a bit of open source software and meant for a bit of fun rather than the real high tech and expensive motion analysis software/equipment you can buy. What it did show of Iwata Sensei's cut was a rather odd trajectory of his kissaki. There were points where it suddenly changed direction within the arch, steepening its angle or shallowing out as though it was operated by a cam system and the acceleration at those points must've been phenomenal. My colleagues on the other hand from a perfectly smooth arch, start to finish. This could've been an artifact or something though.

[chidokan]

ok... how to explain this....thanks for the challenge! His logic sort of goes like this. You need a large 'swing' at the start which gives you high tip velocity at point of contact (larger the circle, the higher the tip velocity) At that point he applies hara /tenouchi/etc to drive the sword downwards. Sword momentum will slow due to interaction with target, so you need to cut harder as the cut goes deeper, until eventually the sword enters the softer tissue below the ribs, at which point the 'circle' continues, but with hara relaxing down to about 10%. This allows control and you are not locking up at the end of the cut, so you can cut immediately again. the sword reaches out for the target point, then the various tensions pull the sword down and back to you. Note this is not usually obvious, as normally you would not be cutting on the spot, but moving forwards. (Think of cutting the sunday joint, you slice it, not axe it...) He used to say 'think of the sound of a bell' for the cutting action.
One thing... he used a 2.25 blade, so was wondering if you extended it to same length as the other guy, what increase do you get? If your friend has the fastest speed at the start, he would effectively be 'burning out' by the time the target is hit perhaps?? Sounds like too much shoulder/arm tension at the start of the cut instead of being relaxed like sensei...

[rottunpunk]

body and left hand magic

And, as Tim says, the cut is the way it is because of what Iwata sensei is aiming to achieve?

What was your colleague aiming to achieve out of his cut?

[Peter West]

There is a simple point of mechanics at work here, but timing it is what takes a lifetime of work. First there is the circle where the shoulder is the centre and the hand describes the circumference, but then with the correct use of tenouchi, the hand (while moving) becomes the centre of a circle with the kissaki describing a circle off it. When these work correctly together it creates a strange kissaki path with greatest acceleration just as the sword is about to hit the target.

[rottunpunk]

A different grip changes the size of the cut also

[Peter West]

Of course, but the real secret/difficulty/technique, whatever you want to call it is to hold lightly enough so the sword has space to move in your hand, but softly closed enough so that every movement in your fingers gets transferred to the kissaki. Most people start the cut with a closed (tight) fist pulling the hand down, but (in my ryuha) we start the cut with the fingers beginning slightly before the hand drops, this cause the kissaki to rise and hence make a bigger path. This don't exactly correspond to Tim's method as their kabuki goes further back and down behind the head, but in that case it is even more important to use the fingers correctly to avoid bashing your head with the tsuba!

[rottunpunk]

hmmn, going through it the hands do move slightly ahead as the kissaki needs to get moving

our kamuri is only right down the back for the basic sets, okuden it should be more natural.
incidently, does Oshita sensei teach the banzai kamuri for koryu, or is it just a training aid for the seitei?

Yes, it is too easy to strangle the tsuka, even when concentrating on not doing so

[Peter West]

hmmn, going through it the hands do move slightly ahead as the kissaki needs to get moving

our kamuri is only right down the back for the basic sets, okuden it should be more natural.
incidently, does Oshita sensei teach the banzai kamuri for koryu, or is it just a training aid for the seitei?

Yes, it is too easy to strangle the tsuka, even when concentrating on not doing so

We use the Banzai kabuki as a teaching aid to prevent people bending their elbows and making the kabuki position too low.

[rottunpunk]

This i surmised when i first saw it.
But i was not sure if Oshita sensei wanted it used in the koryu as well as seitei
Am i reading correctly that when you say kabuki you refer to the 'hands raised above head' position, and not the japanese play?
(My japanese terminology is very lacking)

As you have mentioned, ours is low, and the elbows are allowed to bend to allow this. The reason being the path of the sword is then shorter inbetween cuts.

[Peter West]

This i surmised when i first saw it.
But i was not sure if Oshita sensei wanted it used in the koryu as well as seitei
Am i reading correctly that when you say kabuki you refer to the 'hands raised above head' position, and not the japanese play?
(My japanese terminology is very lacking)

As you have mentioned, ours is low, and the elbows are allowed to bend to allow this. The reason being the path of the sword is then shorter inbetween cuts.

Yes, I meant kaburi not kabuki. Sorry, I should switch predictive text off.
I understand your method requires some bending of the elbow at the highest point, but watching Iwata Sensei, it's no more than necessary. Many people are lazy and allow the elbows to bend much more. In our style the sword only goes back to horizontal in kaburi so there's no need for it. This applies equally to Seitei and Koryu in Oshita Sensei's method. In fact he keeps saying to us "extend the elbows".

[Maro]

Even more fun is to be had when you add left and right Kesagiri to the mix!

[rottunpunk]

Thanks for the confirmation
(for the spelling i figured it must be predictive text, but wanted to make sure)

Indeed, no unnecessary movements
Though i find the banzai kamuri puts strain on the shoulder and makes it harder to control the sword...
But this is more likely to be just my bad technique

[hl1978]

What is actually kind of strange is when you can figure out how to take the weight of your sword and feel it in the crotch/inner thigh and realize that you support it not by pushing up against it with the crotch/inner thigh, but by pushing down with the crotch/thigh to integrate that weight with you so that the resultant force off the ground holds the sword up. It makes the sword go light very similar to how you don't really feel the weight of your own arms when you raise them overhead, but one tends to feel the weight of a sword or any other object when they lift it as it isn't part of your body.

It also winds up leading to significantly stronger cutting power too. It seems strange to me that this is something that is considered "basic" yet no one teaches it.

[chidokan]

its why a few of us got some kihon from Iwata sensei a few years ago....he reckoned we had never had 'the first lesson' so came up with various ideas to help get the points across. What I have noticed during the last year or so is that my students come on a lot faster once they understand this stuff.

[rottunpunk]

indeed, the difficult part is then to 'kick' the kihon 'habit', whilst still bearing them in mind.
The only time i have felt what hl is describing is by doing it 'normally'.

Perhaps it is something that one needs to find for themselves?
Though you did describe it wonderfully.