I wouldn't consider using a 2.5 inch bit freehand, far too much danger of it flying loose and heading at high speed to a major artery. Big bits are for table use.
The power of the router makes some difference, of course, but it helps to cut several times, taking off a little more each pass. I limit myself to about 1/8th per pass by leaving the height pre set, and moving the fence back a little after each pass.
The power of the router makes some difference, of course, but it helps to cut several times, taking off a little more each pass. I limit myself to about 1/8th per pass by leaving the height pre set, and moving the fence back a little after each pass.