I have a series of 2x6 studs that I have drilled two inches holes to pass
PVC pipes across. However I did not realize a 2" hole saw does not make a
hole large enough for a 2" pipe because the 2" is nominal and not outer
diameter.

Now I need to enlarge the hole by about 1/2". My hole saw is not deep
enough to cut a 2x, so previously I cut from both ends and made the cut.
Now that the middle is hollow how can I make a 2.5" hole from a 2" hole?

One solution I think that may work, is to find another piece of 2x and cut a
2" hole, and use the circular wood plug from the cut and insert that into
the 2" hole, and use that to make the 2.5" hole. May be there is a better
way?

MC