I drilled a hole in the top of my spindle sander and made pivoting fence. A bit of threaded rod on the outside clamps to the bottom of the spindle sander table. I use it for all sorts of things, like thicknessing rough nuts and saddles (double-stick taped to a carrier board), sanding the back of the headstock parallel to the face (and thicknessing the headstock), taking pearl cut from shells down to a uniform thickness, .... I find it very useful. The fence is attached to the spindle sander most of the time.