Hi Kevin,
Here's what you need to do.
1. Mount your rotary table.
2. Depending on the type of mill, round column or knee, provide enough head space to indicate the center of the rotary table and still get a cutter to the workpiece.
3. Mount your part. If the part is irregular shaped sometimes it's easier to make up a mounting plate to fasten the part to. This way you can move the part to center and then clamp the plate in place.
4. Indicate an existing center on your part, hole or layout line.
5. Once on center zero out your dials.
6. For a part similar to what you're showing you will also need to have a layout line that runs across the piece. Once you have the part on center square up the layout line by rotating the table as you move from end to end on the layout line. (with a wiggler)
7. Once you have the job squared up mark where your rotary table is positioned or move your reference pointer to an even degree mark.
8. Insert the cutter of choice. A larger diameter will give you a smoother cut.
9. Move one axis off center and then move the table back toward the part until the cutter starts to cut. Before you cut you should know what calculated degree of angle you will need to stop the radius at. This will be the blend point between the radius and the straight wall.
10. Start cutting your radius. Generally I stay about 1/2 degree away from my tangent point until I get the radius to where I want it. This will prevent the cutter from digging in and leaving a mark where the tangent point is. After you have the radius milled rotate the table to the appropriate angle and mill the straight sides. There will be a small amount of stock where you stayed shy of the angle when cutting the radius.
11. Now for your final cut, rotate the table so that your straight cut will be a climb cut. Take a finish pass along the straight wall until you axis dial reads -0-. Rotate the table the required amount until you get to the other tangent angle, lock the rotary table and then make your final straight cut.
12. You should now have a nice smooth, seamless cut from one flat to the radius to the other flat.
13. If you have the part mounted to a plate where you don't have a clamp in the way, rotate the part 180 degrees and do the same for the other side.
14. A light touch will a file and some emery and you have a finished piece.
gbritnell