Bushing the Westclox Baby Ben Alarm Clock Movement

November 17, 2014 | By | 1 Reply More

I once read an article that said “I’ve never seen a Baby Ben movement with enough wear to need bushings.” I have seen many that needed bushings! Any clock that has run for years is bound to have some pivot hole wear.

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Rear view of Baby Ben movement

Most Westclox pivots are polished, hard steel wire. The third through fifth (escape) wheel and pallet pivots of a Baby Ben are made this way.

Westclox center wheel arbors are soft turned soft steel wire, and are not finished very well. Some are rough, and left the factory that way. They may cause bad wear to the front center wheel pivot hole, requiring a bushing. The back center pivot can wear, but unless the wear is super-bad, I prefer not to install a bushing, as a bushing may pop out when removing the time set knob.

Typically, I do the following pivot work to a Baby Ben movement:

  • Sharpen the balance staff pivots (if necessary) and polish them;
  • Polish the balance end screws;
  • Smooth the center arbor pivots with a pivot file, then polish them;
  • Bush the front center wheel pivot hole;
  • Bush one or both time third wheel pivot holes;
  • Bush zero, one or both time fourth wheel pivots holes;
  • Bush the time fifth (escape wheel) pivot holes;
  • Bush the pallet pivot holes (this makes the clock run much better, because it reduces power-losing side-to-side motion of the pallet arbor.

Bushings

I use KWM-sized “American System” bushings. They are small and blend in well.

  • Center Wheel front pivot: #21 bushing, shorten in the lathe to be just slightly longer than the plate thickness, then insert and rivet flush with the front and back of the plate.
  • T3 (time third wheel): pivot diameter about .69mm; bushing #6.
  • T4 (time 4th wheel): pivot diameter .5mm, bushing #5.
  • T5 and pallet pivots: pivot diameter .39 mm, bushing #59.

Use small cutting and smoothing broaches to enlarge the holes to the finished size.

Use oil sink forming tools to shorten the bushing on the outside of the plate (I leave the bushings slightly long to reduce future wear, just be sure the bushing are short enough that the pivot protrudes). Use the oil sink forming tool on the inside of the plate to match the original shape and insure there is enough endshake.

Note: the pivot measurements above are on a Baby Ben movement in a Dura Case 61-D made in 1930.

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Baby Ben movement showing balance and balance spring (hairspring) in the center

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Front view of Baby Ben movement


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Category: Westclox Repair

Last updated: May 2, 2017

Comments (1)

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  1. Daniel says:

    Hello, It will be fun if you make a video about how to dissmantle and reassemble a baby Ben or a Big Ben..I thank you in advance.

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