Suspension Springs for Schatz and Kundo Miniature 400 Day Clocks

On several previous posts, I noted that some Schatz miniature 400 day clocks (model 53 movement) needed a 0.0024 inch thick suspension spring (whereas the Horolovar 400 Day Clock Repair Guide specifies a 0.0023 inch spring).

I just experienced this again – this week I repaired a Schatz “London Coach” 400 day clock (which has the model 53 movement). The clock ran too slow with a Horolovar 0.0023 inch spring. With a 0.0024 inch spring, it keeps good time.

I measured the thickness of the 0.0023 inch springs, and they are closer to 0.0022 inch thick. It may be that a batch of springs were made too thin, or were mislabeled.

I experienced the same thing with a Kundo miniature 400 day clock this week.  With a “0.0023 inch” spring, It needed to have the pendulum regulated almost all the way toward fast to get the clock to keep time. A 0.024 inch spring allowed the clock to keep good time with the regulator near the center of its adjustment.

Conclusion: if a Kundo or Schatz niniature 400 day clock loses time with a 0.023 inch Horolovar suspension spring, install a 0.0024 inch spring.

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  1. I have a Schatz 1000 Day, Series 1040, “54” Movement. Date: 5/55
    Would this have a .0023″ suspension spring?
    Should I buy a .0024 spring just in case the stock spring runs slow?
    I measured the broken suspension spring at .0020, but this is with a vernier metric caliper, so highly inaccurate. Thanks.

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