Milltronics TT-80 Previously repaired, but still needed some TLC
Milltronics TT-80, 10,000 RPM, grease lubrication, coupling driven
Our customer told us that this Taiwanese Cells spindle from a twin table vertical machining center had been previously repaired, but that they had no confidence in the quality of the rebuild. We had to agree with their assessment upon receiving the spindle. The front bearings were quite noisy when rotated in assembly, and we recorded high velocity readings during our incoming test run and vibration analysis which often indicate improper bearing preload or perhaps a misalignment. Additionally, it was noted that the actuator was incorrectly adjusted to allow for proper drawbar operation. Upon disassembly, we found that the front bearing inner spacer had spun on the journal causing severe wear, and that the spacer was heavily damaged as well.
We completed a green grind, chrome plate and finish grind of the damaged bearing journal, and manufactured a new set of bearing spacers. We rebuilt the spindle with all new ceramic bearings, Belleville springs, o-rings and assembly screws. We finished this rebuild with our final test run, break-in, trim balance and final QC. We were apparently successful in our effort to readjust the actuator for proper drawbar function, despite not having an accurate incoming measurement on which to rely.