| Basics of Coordinate Metrology Unit 7: Design of Coordinate Measuring Machines - Fixture | Step 4 of 12 |
| The fixture holds the part during measurement. It is usually made of granite and provided with grooves or threads for locating components for positioning and securing parts. There are no special requirements concerning the flatness of the fixture, since the precision of the measurement is not determined by their flatness but by the straightness of the guideways in the axes of the coordinate measuring machine. The machine base of a coordinate measuring machine carries, in addition to the work holding fixture, all fixed and mobile components that allow the coordinate values to be measured in three dimensions (the only exception are coordinate measuring machines in the gantry style, which have a machine base separate from the work holding fixture). |  Work holding fixture from UPMC, Zeiss |