Tool for lathing rack

The utility model relates to a machine frame turning tool which comprises a lathe body, the right side of the lathe body is rotationally connected with a chuck, the interior of the chuck is fixedly connected with a supporting shaft, and the outer surface of the supporting shaft is detachably connected with a positioning assembly. The positioning assembly comprises a supporting ring, a threaded hole is formed in the supporting ring, a stud is in threaded connection with the interior of the threaded hole, and four connecting blocks are fixedly connected to the outer surface of the supporting ring. According to the rack turning tool, when a rack cylinder body is turned, a supporting ring is connected to the outer surface of a supporting shaft in a sleeving mode and fixed and limited through a stud, then the rack cylinder body is placed on the top of the supporting ring, and meanwhile four screwing blocks are screwed to drive four screws to rotate in connecting blocks; the four screws extend outwards at the same