Excessive clearance in spindle bearings directly effects turning accuracy. The rotating accuracy of the spindle includes two kinds, i.e. run-out and axial slip of it. Run-out of the spindle is guaranteed by two double row roller bearings at the front of spindle while axial slip by single row ball thrust bearing at the rear of spindle. Check method is according to items 5 and 8 in the TEST CERTIFICATE. If the readings exceed the permissible error, in most cases, it is enough to adjust two bearing only. The adjusting method is as follows: Loosen the looking screw on the nut 1(Fig. 12) or the nut 2. After adjustment retighten the locking screws. In case of failure after several trails, adjust rear bearing by the same method as described above. After that, run the spindle idle at high speed for an hour and observe the bearing temperature should not exceed 70° C. If it is exceed, first loosen lock the screws on set nuts (2) and 1, then the nuts (2) and (1) should slight loosened, after the adjustment, retighten the lock screws.

Fig.1  Spindle Structure