I also use the rotary table to lay out holes around the tube. You know about using an edge finder right? what it is and how to use it? Use the edge finder to locate the outer edge of the tube, move the the table an amount equal to the radius of the edge finder, set your zero and move the table in the radius of the tube, now you are over the exact center of the tube. Yeah, you'll get use to thinking about setups and what will clear and what won't, it looks like your moving right along.