Part of the repair process includes bushing worn pivot holes. There are 2 popular friction bushing system sizes: KWM and Bergeon. I recommend KWM-sized bushings for all clocks including Big Ben alarm clocks.
Bergeon bushings are a poor choice in most cases, as they require an overly large hole to reamed. This looks bad and it is considered poor workmanship to remove excessive material from the movement plate.
The bushings I like best are “American System” bushings in KWM sizes, available from the major clock suppliers such as R & M Imports.
Example bushing sizes for a Big Ben style 1:
- T3 pivots: Bushing #13, 1.8 mm outside diameter and a 0.9 mm hole. This bushing is slightly longer than the plate, making it obvious that a bushing has been installed. The length can be turned down to match the plate, or you can leave it long to reduce future wear (the pivot is longer than the bushing in either case).
- T4, T5 and pallet pivots: Bushing #05, 1.2 mm outside diameter, 0.6 mm hole. These bushings are almost invisible after installation.
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