So why are handles installed leaving a machi? The hole in the handle is purposely undersize so the tang is burned in to the handle as tight as possible, and leaving a machi ensures that the tang has been burned in as far as possible. If the emoto is flush to the ferrule, you can't be sure it is burned in properly. And, as Jon said, it makes removing and replacing the handle easier.
Rick, Thanks a lot for your explanation.
Yet, I am still not fully understood why they have the machi; Please bear with my ignorance;
I am just having a hard time to fully appreciate the functional advantage of having the machi.
Basically, I can't understand why the machi makes the removing and replacing of the handle easier.
And why can't they know if a tang is burned in fully without the machi??
I can appreciate if someone says the cut out of metal from the tang making the notch helps weight distribution, thus, balance.
Even so, I think they can achieve the same goal by adjusting the shape/3-d geometry of the tang.
A Shige yanagi that I have does not have the machi. I don't know the shape of the tang inside the handle (if or not it has the notch)
but apparently they do not think that the machi is needed. How come??
I don't mean to sound rude...just try to understand.
If someone says that it's how they had designed the tang area (tradition), I am fine with it. ^^
Karl