It very soon becomes a project in stability..... A mill, or a Lathe, usually have considerable "stiffness & stability" built into the spindle or quill..... so if you can hold the work, you don't have to worry about chatter... if you have a real good drill press, and mount the tool bit as high as you can and move the quill as little as possible, you might have good results IF the work is clamped tight as well.... 5/8" and larger are pretty stout bits, especially if sharp?.... With plastic, you just might get away with it..... turn it slow??? otherwise, you're probably going to have issues...
... best to all, til...lat'r...GT...
