Iaido - The Driving Hand

For the purpose of this explanation, I will let aside the technical Japanese terms.
I have practiced and taught Iaido for over 25 years. At some point I reflected on the fact that some people can’t do clean cuts, I mean those that produce a smooth swishhh, and in other words those that wouldn’t cut through butter, and even less through goza (tameshigiri straw). In order to fix this problem for my students I came up with a simple principle. Why cuts are not clean is a matter of either angle, or blade wobbling during the cut. I subsequently came up with the driving hand theory which for some reason was never explained to me but has proven to work perfectly.

The only cut where both hands and wrists are bent at the same angle is the men uchi (vertical cut to the head). In all other side cuts one of the wrists is bent. The secret to keeping the blade at a proper angle is to keep one wrist always steady, having the hand perfectly aligned with the cutting angle, exactly as if you were striking a bare hand shuto. This hand is the one I call the driving hand. While both hands provide power to the sword, only the driving hand should control the direction.

Therefore, regardless of the cutting angle (downwards, horizontal or upwards) in all left side cuts the right hand will drive the blade, and in all right side cuts the left hand will drive the blade. Students need to cultivate this awareness and with repeated practice, the proper movement will become subconscious and will result in very neat, clean cuts.

To polish this technique, it is necessary to work on series of repeated cuts on one side and direction using the driving hand only. Practice can even be done with a boken as shown in the photos.
Only once the cutting angle is proper can one intend to do some powerful cuts, but this would require an entire article altogether, since transferring power to the sword is even more complex than keeping the blade on a proper trajectory. And even so an article wouldn’t be really helpful as this definitely requires the supervision of a coach.

Enjoy the practice.