[George/Maine]

If you have a vert machine with table that can move in and out and a rotory table.
One way is take the dia and half that for radious 5.6875
Center rotorytable and move out on long machine table 5.6875 don,t move again
mark zero now if the holes a 4" apart guess
Move the table half way 2" in and center drill then drill
Now move rotory table 120 degs drill move another 120 degs back to zero
Now move the table out 2"
Now move rotory table 120 degs drill move another 120 degs back to zero
This is how it was done years ago.