I use a round-over bit with bearing pilot. The radius of the bit must be less than 1/2 the thickness of the material, or the bearing won't ride on the original surface when you round over the second side. Adjust the depth of the bit so that you get a round over without a ledge at the top surface. For internal cuts, you'll move the router in a clockwise direction to avoid the bit grabbing.I made a table saw sled yesterday. I used a drill to make a couple of holes and a jig saw to join them to make a couple of hand holes. Then I wanted to use my brand new router for the first time to 'round off' the holes.
Needless to say, after trying several ideas, I finished the larger-than-wanted holes with a rasp.
What would be the best technique for rounding off internal holes, please?