When I tried to clamp a resaw fence to my bandsaw, I found it very difficult to find a flat section to apply the clamp jaw on the underside of the table because the table has a series of cast iron ribs on the underside for stiffness. To solve the problem, I cut several pieces of scrap lumber of the appropriate size and thickness to fit between the ribs on the underside. A bit of hot-melt glue easily keeps the wood parts adhered in place. Now, there are sufficient “flat” areas for the clamp jaw to rest against when mounting my guide to the top of the table. The same process works equally well for drill press tables.