Hi Patrick,
With tapered ballnose cutters their geometry tends to be the root cause of the issue. It's basically just physically impossible for a tapered ballnose to create a perfect edge due to the radius of the ballnose causing the piece to have a skirt that flares out at the bottom. The only resolution is what you've opted for, which is to come in with a different cutter and remove all of the material after the relief portion is carved. Typically I'll use a 1/8" endmill to mill out a relief, using the 2D Profile Milling operation. This can still result in a sort of discontinuity between the relief and the edges due to the cutters having different geometry. Typically the tapered cutter will have a smaller radius than the endmill and so is able to fit into smaller areas that the endmill cannot.
It looks like you managed pretty well on your own with your attempt! Sometimes finessing the actual geometry being carved can help as well, such as smoothing out the geometry on the edges so that the endmill that's tasked with carving the piece out can reach all of the same areas as the tapered cutter. Sometimes you can get away with using the tapered cutter to cut out a piece, but this can also result in discontinuities at times if the geometry being carved out doesn't entail the tapered cutter reaching all the way down around the piece where a profiling cutpath would traverse. It's a little difficult to explain but the result is that a profiling operation puts the cutter places that it didn't or doesn't go when relief carving, because profiling follows a contour extracted from a single Z plane whereas relief carving follows the geometry at all points. Hopefully that makes sense.
It really just takes some finesse on a case-by-case basis depending on what's being cut and what cutters are being used.
Let me know if you have any other questions or need help with anything else. Cheers! :]
- Charlie