Friction Stir WeldingFriction stir welding of Stainless Steel has successfully been done for over a decade using super abrasive tools such as Polycrystalline Cubic Boron Nitride (PCBN). While traditionally the push has been to increase the tool size for welding thicker sections in a single pass, there has been an increased interest in the use of smaller tools to enable reduction in process forcesProcess forces. This study evaluates the influence of tool features on process forcesProcess forces with the goal of welding below 8900 N. The tool features investigated in this study are primarily tool diameter, pin height, shoulder height, and thread revolutions on both the probe and shoulder.