sanding edges

One small batch of sycamore ring boxes shouldn't take too long but I hit a snag.
I think at the root of the problem was the rather light weight fast grown sycamore I was using. Normally sycamore is pretty dense and cuts beautifully but this particular tree was an exception. I've never seen growth rings in sycamore so far apart.
I made the ring boxes as usual and got a good finish with sandpaper but when I came to cut the quarter rounds on the edges I was left with a ragged edge.I was using a block on a small spindle moulder with a high speed knife which was as sharp as it could be. ( the peripheral speed of the cutter blade is a lot faster than using a router.) I tried sanding them by hand but what I really needed was some sort of machine to neatly, evenly and cleanly  sand the round overs. I just couldn't think of a way of doing it. So I spent almost an entire day building a jig. It was partly successful but if anyone out there in blog land can think of a better solution I shall be forever in your debt.