I learned the shinai swinging mechanism at the 8th Nito Seminar. The mechanism is very helpful for all the kendo practitioners but I do not want to make it to the public because I am still learning.
If you have some spare shinai, prepare two pieces of bamboos from the shinias you no longer use. Then tape them together like the photo above. Then mark where you think the center of mass is.
The reasons that you make this shinai is
So you can strike one handed strike without unnecessary strength.
This is very very important. If you use a normal shinai, you will put extra strength to swing the shinai down and stop it. This will develop unwanted habits. So we want to have a light shinai.
Once you have the light shinai and marked the center of mass, then time to swing it down. What you should do is
When you extend your arm here is what you should pay attention.
Once you lift up the shinai as the mark goes up above the eye level, just extend your arm so the mark is going toward the target.
You can feel how effective it is to strike a target with this method.