Divided type φ6 herringbone grooved journal gas bearings have been developed to support high rotational speed practical rotor for a micro rotary machines such as a palmtop gas turbine generator. Critical mass of a rotor and radial clearance of journal and thrust bearings are designed to rotate over 800,000 rpm. Test journal bearings have radial clearance of 8 μm and mass of 4.2 gram. Roundness under the processed and the reassembled condition of the test radial bearing was measured by using 3-D CMM and was compared to verify repeatability of assembling bearing parts. The precision by reassembled condition was obtained 3.5 μm. Test of this bearings were carried out using a test rig. Spectra under the rotation and the orbit were measured by using displacement meter. Maximum rotor speed exceeded 804,000 rpm and the stably orbit was obtained.
