Journey to the center of your clamp-ups for even pressure
For good edge-to-edge glue-ups, it’s important that the clamping pressure be evenly applied across the thickness of the workpiece edges. Unfortunately, many clamps exert more pressure near the bottom or top of workpiece edges. That can result in the glue-up bowing, the boards shifting out of alignment, poor glue bonds, or all three issues. To ensure centered clamping pressure, insert dowel rods of the same diameter as the board thickness, as shown.
—Frank Orth, Andale, Kan.