Perfect for Sanding Wooden Bowls, Platters and More. Sanding curved surfaces like wooden bowls can be challenging and can take a long time to finish when sanding by hand. Sanding your project by hand can also cause fatigue and produce unsatisfactory results. The ¼” shank sanding mandrels have a thick padded base that conforms to concave or convex surfaces. Simply secure the mandrel into a variable speed drill or flexible shaft and you’re ready to go. 129 Piece Set