Drilling out rivets can seem like a step backwards for any builder, but you can also look at it from another direction and realize that if you need to do it, you NEED to do it--and therefore, it is a step forward towards completion, or in this case, in the direction of finishing a repair.
We’re working on the reinforcement doublers for the belly skin of our Tundra, and the first step, before we can shape and fit the doubler panels, is to get all of the rivet heads out of the way. You know you’re on a roll when you can build up a nice stack of concentric factory heads on your drill bit. Don’t be surprised if you don’t get results like this right away – I’ve been working on airplanes for over forty years, and didn’t get good at drilling these things until maybe the last decade. Some of us are just slow learners.
I find that using an automatic center punch to deepen the dimple on the standard AN470 rivets makes it much easier to center the drill bit if you’re free-handing it. Short bursts on the drill (I prefer air drills for this) help to get it started, and you might have to steer it just a little bit before going full blast. You should be rewarded with a nice head on the drill bit, and the shop head popping out the back side of whatever you are working on. Drill guides make the job even easier, especially if you’re new.