I used an endmill (1/16 inch) which has an 1/8 inch shaft... I just used the shaft about an 1/8th of an inch into the tube and pulled it at an angle around in a circle... copper is soft so it flares. Not right away, but after about 10 circles.
I'm not concerned with the loss of pressure at the outer jets. I just want to see how this will work. Probably better than the block I have now.
We will see... that's why I'm making it.
