Datum plane: the base of vehicle inspection tool must be set at X, Y, Z datum plane at least. The datum accuracy must be machined by grinding.

The base plane coordinates directly intercept the body coordinate values.

- the perpendicularity of the length and width direction datum X- and Y- faces is: +/-0.05mm/1000mm

The height datum: the Z- plane for the lower part of the bottom plate, its flatness must be 0.05mm, and the parallelism of the upper plane of the base plate shall be 0.1mm/1000mm.

Datum hole: in order to process the automobile gauge or use the fixture to carry out the three coordinate measurement, it is convenient for the fixture to be accurately fixed on the machine tool table, and the reference hole is set at the same time. The pitch of the reference hole is 200 mm, and it should fall on the 100 bit line of the vehicle coordinate system. The two datum holes should be marked (circular hole 1 and ellipse 2) and mark the coordinate values.

- install the coordinate line nameplate beside the datum and datum hole. See Annex VW 39D725.

The bottom plate of the fixture is required to carve a coordinate line, and the tag of the fixture is fixed on the bottom plate.

- the reference hole of the small gauge can be selected separately.