Pivot Restoration

Pivots in clocks are the working ends of the gear arbors that rotate within holes drilled in the plates of a clock movement, as the clock runs. They are subject to wear, especially when maintenance is neglected.


Excessive wear on the pivot shown at the far left of this photo will be eliminated by using a small precision “WW” lathe.


A closeup view of the worn pivot.


Even closer, the effects of long-term neglect are easily seen in the eroded working surface of the pivot.


Before the most worn areas can be restored, it is necessary to cut away material on the unworn areas.


A little ways to go, still. As long as at least 70% of the original pivot diameter remains after material removal and burnishing, the pivot will retain structural integrity.


Finally, the pivot shoulder will be broadened, the pivot will be given a final burnishing, and the restored pivot will be ready to go back into service.


This poor pivot has been all but destroyed by a well-meaning but ill-informed would-be repairer, who appears to have cut away what he perceived to be wear, with of all things, a powered grinding wheel.  It takes little imagination to picture what this did to the mating pivot hole, when an attempt was made to put this clock back in service.

Note also, the damaged pivot shoulder, which should be smooth and flat to operate smoothly, but in this case was ground almost conical.


Even after much of the metal has been removed, the full extent of how aggressively and deeply damaged this pivot was is revealed.


Almost there.


The pivot restoration is nearly completed, and the pivot shoulder is partially restored in this view.


Nearly completed, only a little more work is needed to broaden the pivot shoulder and make a final burnishing pass over the pivot. Upon completion, this wheel, arbor and pivot will be ready to resume service. The reduced pivot diameter will require re-sizing the hole that the pivot rotates in.