God I'm surprised only one guy told you the right answer... You use a "step bit", Home Depot has them, they are cone shaped and cut 1/16 or
1/8 inch per step, you stop pushing when you hit the 3/4 inch step. They cut very fast, clean, and round especially through aluminum, but set the drill slower for aluminum. They are not cheap bits but well worth the money for metal fabrication jobs.