General testing fixture used for measuring diameter and circularity of automobile circular casting

The utility model relates to a general testing fixture used for measuring the diameter and circularity of an automobile circular casting. The general testing fixture includes a base plate, a scale fixed block, a copper sleeve, a scale, a jackscrew, a positioning pin fixed block, a positioning pin, a central handle, a measuring handle, a verification sample block, and screws. The two ends of the base plate are a measuring end and a positioning end. The measuring end of the base plate is provided with a square through hole. The scale fixed block and the positioning pin fixed block are rectangular blocks which are provided with through holes and are fixed on the base plate. The copper sleeve is arranged in the through hole of the scale fixed block and has a sliding fit with the through hole. The scale is inserted into the copper sleeve and is fixed via the jackscrew. The verification sample block is in a concave plate structure, and inner side faces of the two ends of the verification sample block are verificati