The various types of limit gauges used for gauging external diameters of shaft are

1)   Full form cylindrical ring gauge: The gauging surface is in the form of an internal cylinder and whose wall is thick enough to avoid deformation under normal conditions of use.

2)  Gap gauge: It has one flat surface and one cylindrical surface, the axis of the two surfaces being parallel to the axis of the shaft being checked. The surfaces constituting the working size may both be flat or both cylindrical also.

The gauges (for internal taper) are marked with a ring on the gauge planes another ring to indicate the minimum depth of internal taper.   The distance between the two ring marks „Z‟ corresponds to the permissible deviation of the gauge plane for particular taper. For testing the external taper of the tanged end shank, the ring gauge is inserted, as far as it goes with light pressure.   At the extreme position, no part of the tang under test should extend beyond the surfaces A, B and C. The shank surfaces may however, lie flush with these surfaces.