This post will detail the process of correcting a worn center pinion pivot bore. The patient is an Elgin Model 6, grade 151, a seven-jewel pocket watch. This particular watch had high mileage, as evidenced by the fact that all of the pivots needed to be trued and polished, and their bores needed to be bushed. I will detail here the bushing of the center pivot only, as the rest of the train was handled in a similar manner.
The video clearly shows the extent of wear. Naturally, because the center pinion is subject to the highest torque input, it is also subject to the most wear (especially in a non-jeweled watch).
After truing and polishing the pivots in the lathe (and establishing the pivot's new finished diameter), the blank bushing is turned up. It is a blank in length only, as the inside diameter is drilled and reamed, and the outside diameter are established in the lathe.
Here, the barrel bridge is reamed to accept the bushing.
The bushing is then pressed in, leaving enough protruding to set the end shake. If the bushing looks a bit crooked, it is because it is just placed on top of the hole while I took the photo.
The end shake is set, using a shop-made cutter.
The well is cut and polished and that's it for that one (only seven more to do).
The result of many hours of work...
No comments:
Post a Comment