You should leave just enough stock so that you can obtain a surface finish of Charmilles 42, but not too much more, or it will take you all day.
Proud Member of the Reality-Based Community..
[green]To the Toolmaker, your nice little cartoon drawing of your glass looks cool, but your solid model sucks. Do you want me to fix it, or are you going to take all week to get it back to me so I can get some work done?[/green]
By this chart, it looks like a 63 micro inch, which is not rocket surgery, milling, turning or grinding will get you there. I'd still talk to the people who will be finishing the part for you.