A double base welding positioner is a machine that is used to hold and position workpieces for welding. It consists of two bases that are mounted on a rotating platform, and a pair of jaws that can hold the workpieces in place. The positioner can be adjusted to various positions and angles, allowing the welder to easily access the weld joint from all sides. This makes it easier to perform high-quality welds in difficult-to-reach locations, and helps to improve the efficiency and accuracy of the welding process.