Short of having a wood lathe handy, why don't you just drill a 3/8" hole in the end of the 5/8" dowel. Use a small piece of a 3/8" dowel as a .......dowel. If you're careful marking the center on the 5/8" dowel, center punch it with a pointy awl, it shouldn't be difficult at all.
Mike Hawkins:smile:
Mike Hawkins:smile: