Welding and Metalworking - milling question

I have a question about milling a radius on a manual xy milling machine. How is it done. I have never done any kind of milling before but I have some very basic parts to make that are essentially a 2.5"x.65" rectangle but there is a step down on both sides of the part. so the part is 2.5" long and at one end it is .65" and the other is .48" how is the radius cut?

You say "radius" but what you describe sounds like you want to cut the face on an angle (tapered).

If you are radiusing I use a radius bit and run down the part. Bits are available with different radii.

If you want to cut an angle there are two easy ways that come to mind. Counting with my toes I figure you want a 3.89 degree angle. Adjust the head of your machine to that angle and start milling (I'd start off shallow in case the angle is not correct so you can adjust as needed). If you don't want to screw with the other axis of your mill just clamp the part crooked so your normal horizontal cut ends up being a taper. Basically clamp the part so one side is .17" higher.