1972 - This large 3 coordinate measuring machine was fabricated for the construction of Bailey Bridges. A 10 tonne "X" carriage traverses a 22 tonne bed sitting on 3 kinematic support feet. A separate operator's carriage is guided on independant "non-influencing" rails. The 4m X carriage carries a counter balanced 2m Z slide which in turn carries a Y probe carrier of 0.8m travel. The pitch, roll and yaw are better than 2.5 seconds for the total travel of each axis. Optical gratings provide 1µm resolution, (later 0.2µm), to create a volumetric accuracy of 25 µm or better anywhere within the working volume.
1975 - The machine uses hydrostatic bearings throughout with natural granite based linear ways. The machine is totally enclosed and swamped in a temperature controlled oil mist to ±0.1°C. The main work table slide is a trapped hydrostatic bearing mounted to be normal to the wheel infeed to make roll and yaw error motions second order.
Component accuracy - cylindricity better than ±0.1µm over 50mm of length, diameter to ±0.2µm, and surface finish 24nm CLA on hardened steels.« Back Next »