Set screws often have a head smaller than the outer diameter of the screw. Designs with a single screw or three screws instead of two exist. Some use a ball screw and ball nut. There is no universally accepted distinction between a screw and a bolt. The distinction between a bolt and a screw is commonly misunderstood. The tensioner is either operated by turning a screw or a manual wheel. This distinction is consistent with ASME B18.2.1 and some dictionary definitions for "screw" and "bolt". It is a spline tip with a corresponding recess in the screw head. They simply refer to the size of the threads relative to the screw diameter. Professional bassists are more likely to have adjustable bridges, which have a metal screw mechanism. She's got a screw loose somewhere. Threading is the process of creating a screw thread. A screw drive is a system used to turn a screw. Some cans have screw caps for pouring liquids and resealing. Most instruments screw onto a tripod when in use.