I'm contemplating enlarging a small letterbox in a wooden door. I'm not 100% sure that the site of the intended larger hole is completely solid, which might make the proecess more difficult than otherwise, but I suppose that all I can do is proceed carefully and - if necessary - try to fill in gaps in the frame if I find some?
What's the "standard" way to enlarge an existing hole? Do I use a saw, or drill lots of holes and then knock sections out with a chisel, or what? Or a power jigsaw (carefully)? I'm not planning on taking the door off its hinges unless that's absolutely necessary.