Hi Randy,

> I’m not sure how to get that nice sweeping surface to join with
> the face of the key but still retain the fillet on the other edges.

Maybe something like this - since it sounds like the rest of the model is already set up how you want, it's probably easiest to do some surgery just in the localized area of it instead of trying to redo everything.

So that little shelf is kind of interfering with what I think is the kind of sloped shape you actually want so I deleted it, and put in a new sloped surface by drawing a curve here: (viewed here from the underside of the model with the back surfaces hidden)



And then extruding it:




Then I drew in a couple of lines and used those lines and also the edge of that extruded surface as cutting objects in the Trim command to trim that surface like this:



So if I understand correctly, this is a lot closer to the shape you want - a lot of times you may want to kind of get some bigger pieces set up the way you want and then take a look at what is going on with the surrounding areas.

One way to fill in the surrounding areas is to do a sweep.

To do that, select these edges and use Edit > Join to make a new curve that goes across all of them:



Now select that curve that was just created and also the top edge - these will be used as the profile curves for sweep:




Now run the Sweep command, select these side edges as the rails (I used the merge command to merge together 2 edge fragments on one side into 1 single edge but you could also use join for that as well):




So that will build a fill-in piece that takes the shapes at the ends of the fillets and slides them along those side rails while gradually flattening them into the end shape, it produces a result like this:



Is that close to what you were looking for?

The 3DM model file of that result is attached.

- Michael