Originally Posted by jrd22
I've used a piece of wood as a guide for the larger hole saw. Use a piece of 2X and drill the diameter of the existing hole then put the cut out on the pilot bit with the larger hole saw.
Edit: Oooh, I think I need one of those oopsie arbors:-))
John, I've done similar many times.. the only place the 'oops' arbor won't work is if you need to realign or slightly move the hole center.. that CAN be done with a predrilled template as you suggest.
Another thing I've been able to do is to clamp the drill into one of those portable drill press thingies, spin the drill around, stand on the base and position the hole saw that way.. but that requires a decent surface to work on.