I don’t have room in my workshop or the budget for a dedicated oscillating spindle sander. But I figured out a way to get similar functionality from my drill press with some simple hardware.
As you can see in the photos and drawings, I secured a thin rope from the depth stop adjustment to a simple foot pedal. When the pedal is depressed, the sanding drum lowers into the auxiliary table. Continuous up-and-down pedal motion mimics the action of an oscillating spindle sander and makes more even use out of the drum.
Assembly. The drawings show how the assembly goes together. You can find most of the items at the hardware store.
With everything in place, use the oscillating feature by raising the table until the bottom of the drum is at the table surface.