Special simple detection tool for detecting depth of semicircle

The utility model discloses a special simple testing fixture for testing the depth of a semicircle, which comprises a base and a dial indicator, and the measuring end of the dial indicator vertically penetrates through the base downwards and then extends to a calibration standard base. A connecting mechanism is arranged below the base; the width of the connecting mechanism can be adjusted according to the width of the measured semicircular groove. According to the utility model, the dial indicator is fixed on the base, and the screw rod of the width adjusting mechanism is provided with the first thread section and the second thread section which have the same lead and opposite screwing directions; during detection, the base is placed in a semi-circular groove of a workpiece, the screw rod is rotated to enable the left convex block and the right convex block to be symmetrically away from the symmetry axis of the screw rod, the left convex block and the right convex block are in close fit with the semi-circular