I have a bar that is ~.55 inches in diameter. I have a hole that is currently drilled out to 3/8 with drill bit. I want to turn down the bar and or enlarge the hole so that have a tight fit that is accurately centered and will resist radial forces. I assume that I would probably want to use a key to prevent slipping. What would be the best way to go about doing this? I do not have access to a mill or press.