I would like some input on what you feel is the best way to make butterfly keys. So far, I've made a jig for my bandsaw that seems to cut a pretty symetrical key that I am happy with. However, I am having difficulty getting a good fit when I cut the mortise to take the key.

I have been marking the outline of the key with a knife, mortising out the majority of wood with a plunge router, then trying to clean up the edges with a chisel. This seems to be a pretty standard installation method, and maybe I just need more practice to get it tight, but I'm listening to any other ideas out there.