QD12-08-C Parallelism

To determine the deviation in parallelism of a point on the rotary surface and the bottom (seating) surface of the rotary table.

Parallelism error is defined as the height difference fp between 2 planes parallel to the seating surface within which all measured points must be.

The rotary table assembly and a high-resolution linear probe and stand are placed on a granite surface plate. The probe is positioned on the top at a diameter position of approximately 0.9 x diameter and zeroed. The stand and probe are not moved but the complete rotary table is slid on the granite and re-positioned where the probe is now at a position approximately 90° from the original on the table top. The table top is rotated 90° in the reverse direction to the base movement. The dial indicator reading is noted and the process repeated at 180°, 270° and 360° positions.